EPA-600/2-77-175
August 1977
Environmental Protection Technology Series
INFLUENCE OF RECYCLING BEEF CATTLE
WASTE ON INDIGESTIBLE RESIDUE
ACCUMULATION
Robert S. Kerr Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Ada, Oklahoma 7482Q
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-77-175
August 1977
INFLUENCE OF RECYCLING BEEF CATTLE WASTE
ON INDIGESTIBLE RESIDUE ACCUMULATION
by
Donald G. Wagner
Barbara A. Ackerson
Ronald R. Johnson
Oklahoma Agricultural Experimental Station
Stillwater, Oklahoma 74074
Grant No. R-803274
Project Officer
Lynn R. Shuyler
Source Management Branch
Robert S. Kerr Environmental Research Laboratory
Ada, Oklahoma 74820
ROBERT S. KERR ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
ADA, OKLAHOMA 74820
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DISCLAIMER
This report has been reviewed by the Robert S. Kerr Environmental Research
Laboratory, U.S. Environmental Protection Agency, and approved for publication.
Approval does not signify that the contents necessarily reflect the views and
policies of the U.S. Environmental Protection Agency, nor does mention of trade
names or commercial products constitute endoresement or recommendation for use.
ii
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FOREWORD
The Environmental Protection Agency was established to coordinate
administration of the major Federal programs designed to protect the
quality of our environment.
An important part of the agency's effort involves the search for
information about environmental problems, management techniques and new
technologies through which optimum use of the nation's land and water
resources can be assured and the threat pollution poses to the welfare
of the American people can be minimized.
EPA's Office of Research and Development conducts this search through
a nationwide network of research facilities.
As one of these facilities, the Robert S. Kerr Environmental Research
Laboratory is responsible for the management of programs to: (a) investi-
gate the nature, transport, fate and management of pollutants in ground-
water; (b) develop and demonstrate methods for treating wastewaters with
soil and other natural systems; (c) develop and demonstrate pollution con-
trol technologies for irrigation return flows; (d) develop and demonstrate
pollution control technologies for animal production wastes; (e) develop
and demonstrate technologies to prevent, control or abate pollution from
the petroleum refining and petrochemical industries; and (f) develop and
demonstrate technologies to manage pollution resulting from combinations
of industrial wastewaters or industrial/municipal wastewaters.
This report contributes to the knowledge essential if the EPA is to
meet the requirements of environmental laws that it establish and enforce
pollution control standards which are reasonable, cost effective and
provide adequate protection for the American public.
William C. Galegar, Director
Robert S. Kerr Environmental
Research Laboratory
iii
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ABSTRACT
Studies were conducted to investigate the effect of feces recycling in
beef cattle diets (rations) on the digestibility of various dietary nutrients
and on the accumulation of indigestible residues. Feces were refed in three
successive phases based primarily upon the quantity of feces produced in the
previous phase. Several different roughage levels in high concentrate
rations were considered. An attempt was made to investigate the digesti-
bility of various nutrient parameters in feces when refed and the roughage
value of feces. Mineral retention data and the accumulation of various
minerals in the fecal and urinary residues were studied. Varying levels
of feces in growing/maintenance rations were investigated along with the
efficiency of urinary nitrogen (N) as a supplemental N source.
This report was submitted in fulfillment of Grant No. R-803274 by
Oklahoma State University, Animal Science Department, under the sponsorship
of the U.S. Environmental Protection Agency. This report covers a period
from July, 1974, to August, 1976, and work was completed as of June, 1977.
iv
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CONTENTS
Foreword
Abstract
Figures
Tables
Abbreviations and Symbols
Acknowledgments
Sections
I Introduction
II Conclusions
III Recommendations
IV Literature Review
V Trial 1—Recycling Digestion Trial with Steers
VI Trial 2—Recycling Digestion Trial with Steers
VII Trial 3—Nitrogen Depletion-Repletion Study
VIII Trial 4—Digestion and Growth Study with Lambs
IX Trial 5—Heifer Growth Trial
X References
Page
iii
iv
vi
vii
ix
1
2
3
5
11
30
51
63
68
71
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FIGURES
No. Page
1 Schematic Diagram of the Experimental Design Used in Trial 1- • 15
2 Percent Absorbed Nitrogen Retained 56
3 Grams of Protein Retained 57
vi
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TABLES
NUMBER PAGE
1 Theoretical Digestibilities as Calculated by Difference
for Feces Produced by Roughage and Feedlot Rations 9
2 Composition of Rations Fed in Trial 1 13
3 Apparent Ration Digestibilities of Dry Matter, Ash and
Crude Protein in Trial 1 18
4 Apparent Ration Digestibilities of Acid-Detergent Fiber,
Lignin, Cellulose and Neutral Detergent Fiber in Trial 1 . . 19
5 Apparent Digestion Coefficients for Cattle Feedlot Waste—
Calculated by Difference 21
6 Composition of Feces in Trial 1 23
7 Composition of Urine in Trial 1 24
8 Indigestible Fecal Residues in Trial 1 25
9 Residues from Trial 1 Excreted in the Feces and Urine ... 26
10 Utilization of Sodium in Trial 1 28
11 Utilization of Chlorine in Trial 1 28
12 Utilization of Calcium in Trial 1 29
13 Utilization of Phosphorus in Trial 1 29
14 Composition of Rations fed in Trial 2 32
15 Apparent Digestibilities of Dry Matter, Organic Matter, Ash
and Crude Protein in Trial 2 Rations 34
16 Apparent Digestibilities of Acid-Detergent Fiber, Lignin,
Cellulose and Neutral Detergent Fiber in Trial 2 Rations . . 36
17 Digestibility of Feces as Calculated by Difference for
Trial 2 38
18 Digestibility of Feces Component when Recycled 39
vii
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TABLES (continued)
19 Composition of Feces in Trial 2 40
20 Composition of Urine in Trial 2 42
21 Indigestible Nutrients Excreted in Feces in Trial 2 .... 43
22 Residues which Accumulated in Feces and Urine in Trial 2 . . 45
23 Sodium Retention in Trial 2 47
24 Chlorine Retention in Trial 2 48
25 Calcium Retention in Trial 2 49
26 Phosphorus Retention in Trial 2 50
27 Nitrogen-Depletion Ration fed in Trial 3 52
28 Nitrogen-Repletion Rations fed in Trial 3 53
29 Composition of Feces and Urine Used in Trial 3 Repletion
Rations 53
30 N Balance for Week One of Trial 3 55
31 N Balance for Week Two for Trial 3 58
32 N Balance for Week Three of Trial 3 58
33 N Balance for Week Four of Trial 3 59
34 N Balance for Week Five of Trial 3 60
35 N Balance Summarized over the Five Week Period 61
36 Composition of the Rations fed in Trial 4 64
37 Apparent Digestibilities of Rations in Trial 4 65
38 Mineral Retention in Trial 4 66
39 Growth Data on Lambs in Trial 4 67
40 Composition of Rations fed in Trial 5 69
41 Growth Data on Heifers in Trial 5 70
viii
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LIST OF ABBREVIATIONS AND SYMBOLS
ABBREVIATIONS
ADF —acid detergent fiber ml —milliliter
ad lib —ad_ libitum NDF —neutral detergent fiber
C.P. —crude protein NPN —non protein nitrogen
CSH —cottonseed hulls O.M. —organic matter
Dig. —digestibility Per —period (division within a
DM —dry matter phase)
g —gram Ph —phase
hr —hour SEM —standard error of mean
I.U. —International Unit Supp —supplement
kg —kilogram
SYMBOLS
Ca calcium
Cl chlorine
kg *75 metabolic weight
N nitrogen
Na sodium
NEg net energy for gain
NH
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ACKNOWLEDGEMENTS
The authors gratefully acknowledge the dedicated assistance and co-
operations of Kathy Hamilton, Tom Fuller, Cindy Miller and Russell Givens
in helping with the laboratory analyses. A note of thanks is also extended
to the animal caretakers for their assistance in conducting this study.
The invaluable assistance of Mary Ann Nichols and Daryl Buccholz of
the Agronomy Soils Lab in conducting the mineral analyses is acknowledged.
Appreciation is also expressed to Dr. D.L. Weeks, Dr. R.R. Frahm and Mike
Brown for their help in the statistical analyses of the data.
The technical assistance Mr. Lynn Shuyler, Project Officer, provided
in writing of this report is greatly appreciated. Thanks are also extended
to Connie Doss for the typing.
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SECTION I
INTRODUCTION
In large cattle feedlots, feedlot waste is produced in huge quantities
and must be disposed of by some means. Moreover, unless managed properly,
beef waste can be a potential pollutant in our environment. With today's
trend toward intensive production systems, efficient and economical alter-
natives must be found for effective disposal of animal waste materials.
Traditionally, in many areas animal waste has been placed on land as a
source of plant nutrients. This method may not be practical, however, in
many instances because of the large quantities of land which may be required,
expense, potential air and/or groundwater pollution, and other consider-
ations .
Recycling of feedlot waste as livestock feed merits investigation as a
potentially useful source of feed nutrients and as a means of lowering the
disposable waste load. Either partial or continuous recycling of waste as
feed should reduce the total amount of disposable waste and also the bio-
logical oxygen demand associated with decomposition of waste through the
loss of organic matter. Animal waste may provide useful nutrients such as
fiber, nitrogen, energy and/or minerals in the diets of ruminants. There-
fore, studies were conducted herein to evaluate the following overall
obj ectives:
1) Evaluate the effect of continuously recycling solid beef cattle
waste on the digestibility of waste and on the accumulation of
indigestible residues.
2) Determine the influence of roughage level in high concentrate
rations on residue accumulations during recycling.
3) Determine the influence of recycling beef cattle waste on digesti-
bility of ration nutrients, ration palatability and animal per-
formance .
4) Determine the efficiency of nitrogen utilization from dried urine
as a supplemental nitrogen source.
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SECTION II
CONCLUSIONS
Ration digestibility was decreased by inclusion of feces in the ration.
Feces produced on high concentrate rations were recycled (refed) in 4 con-
secutive phases through steers. Total disposable waste load was reduced by
refceding, indicating some further digestion or utilization of feces when
refed. Calculated digestibility values for the feces component in a ration
(diet) indicate a low to moderate, but variable digestibility for various
nutrient parameters in feces being refed. Dry matter digestibilities ranged
from 27 to 61% with protein, fiber and ash values usually being lower than
this. Digestibility of fiber components tended to increase with each re-
cycling. Feces in diets containing either zero or very low levels of rough-
age appear to have some roughage value and produce positive, associative
effects, increasing ration digestibility. The composition of feces was
altered by continuous refeeding such that the feces produced were slightly
higher in protein, fiber and ash content. Recycling of feces in the feed
produced an accumulation of Ca, but resulted in no material buildup of Na,
Cl or P. Normal mineral retention values were observed in animals.
Physiological or nutritional status of an animal appears to influence
digestive efficiency and efficiency of nitrogen (N) retention. Young lambs
which were placed on a low nitrogen depletion diet for 4 weeks showed higher
ration digestibilities and more efficient nitrogen retention during the
first 2 weeks following the depletion period than 3 to 5 weeks following N
depletion.
Urinary N appears to be readily utilized for microbial protein synthesis
in the rumen. Diets containing either 0, 25 or 50% of the supplemental N
from urine (soybean meal served as the control N source) promoted approxi-
mately equal efficiencies of N retention in young, N depleted lambs. When
75% of the supplemental N was supplied by urine only a slight decrease in
N retention was observed. After N reserves were repleted (by fifth week),
no treatment differences were observed.
Increasing the level of dried feces (0, 20, 40, 60%) in a ration caused
a general reduction in total ration digestibility, but produced normal
mineral retention. Dietary intakes on rations containing an increasing
level of feces were very acceptable. Growth data with both lambs and cattle
indicate that high feces rations are low in energy, but appear to be very
acceptable for maintenance type programs.
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SECTION III
RECOMMENDATIONS
Feces produced from cattle on high concentrate finishing rations can
be refed or recycled in cattle diets. Feces will have a low to moderate
nutrient digestibility and can be best used as a major dietary component in
maintenance type rations which do not require a high caloric density or
energy (Total Digestible Nutrient or Net Energy) value. In such rations,
rather high levels (perhaps 50%+) can be included. Adaptation to such diets
and acceptable feed intakes can be achieved in a relatively short time—
perhaps several weeks or less.
In high concentrate finishing diets, feces may be included because of
its apparent roughage replacement value. In zero roughage diets, feces also
produce favorable associative effects, enhancing digestibility.
Recycling of feces can be practices to decrease the total disposable
waste load. Further digestion appears to occur when feces are recycled.
Fiber, in particular, appears to undergo more complete digestion when
recycled.
Although feces were dried and ground prior to reincorporation in the
diet In these studies, systems which incorporate wet feces (e.g. ensiling
programs) would logically provide a more energy conserving approach. The
feeding (nutritive) value of feces under field conditions would likely de-
pend upon various factors. For one, any compositing which occurred would
greatly lower potential energy value for feeding purposes. Moreover, if
sand, dirt, etc. were included any potential feeding value would decrease
accordingly. If conditions favored very high starch digestibilities in the
grain fed, the resulting feces would have a lower refeeding value and con-
versely. Most field situations would probably result in poorer ration
starch digestibilities (in zero feces rations) than observed in the studies
reported herein. Hence, under field conditions, feces would probably have
a somewhat higher starch content and potential refeeding value than in the
studies reported here.
The crude protein in feces appeared to have a relatively low digesti-
bility, but the efficiency of N utilization from urine appeared more favor-
able. Hence, urine in particular, might serve as a source of supplemental
dietary N in some cases. Refeeding waste does not appear to create any
problems with normal mineral retention in animals.
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More definitive studies are needed in which 1) feces are recycled over
more successive refeeding phases, 2) feces are included at varying levels in
recycling test diets, 3) time is not a variable when comparing digestibili-
ties in one refeeding phase vs another, 4) both feces and urine are included
simultaneously for refeeding purposes, and 5) more types of diets are studied
in recycling programs.
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SECTION IV
LITERATURE REVIEW
EARLY RECYCLING WORK WITH CATTLE FECES
Pioneering work on the feasibility of refeeding steer manure was done
by Anthony and Nix (1962) and Anthony (1966). In these initial trials, the
solid portion of manure was separated from the liquid portion by vibrating
screens or by adding additional water, allowing the solids to settle and de-
canting the water. The solid portion was then mixed in fattening rations
in a 2:3 ratio, as-is, and fed to steers. However, on a dry matter basis
the manure would have composed a much smaller fraction of the ration (ap-
proximately 20%). In a subsequent trial, cooked, washed and unwashed manure
were compared (Anthony, 1970). It was concluded that neither cooking or
washing of manure resulted in any improvement in feeding value. Anthony
observed manure to have no negative effects on ration digestibilities of
dry matter, crude protein or cellulose. This suggested manure to be of
some nutritive value for productive purposes.
Ensiling Manure and Recycling
Refeeding fresh manure will only partially alleviate waste disposal
problems. In Anthony's (1970) studies, only about one-half of the manure
collected'daily was refed and the remainder discarded. Thus, the concept
of wastelage was developed by Anthony (1966, 1967, 1968, 1969) and Bandel
and Anthony (1969). Wastelage was a term coined by Anthony to describe a
combination of fresh manure mixed with ground grass hay (e.g. 57 kg of
hay/43 kg of wet manure on an as-is basis) with the mixture being stored
in a silo until fed. Fermentation occurs, and the product develops a si-
lage odor while much of the manure odor disappears. Such a method of pro-
cessing manure might effectively permit utilization of feedlot waste as
feed and reduce disposal problems.
When Anthony (1969, 1971) combined 40% wastelage (wastelage consisted
of approximately 80% hay and 20% manure on a dry matter basis) with 60% corn
on an as-is basis and fed the mixture as a finishing ration to steers,
average daily gains were equivalent to those on either a convential high
concentrate finishing ration or a conventional high concentrate ration con-
taining 40% fresh (as-is) untreated manure (Anthony, 1971). Anthony (1968)
further reported corn silage fed cattle to be out-gained by wastelage fed
cattle in two trials. However, the differences were not significant.
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Breeding ewes and beef cattle have been adequately maintained on waste-
lage for up to a year when supplemented with Vitamin A (Anthony, 1967, 1979).
During this period, the animals went through breeding, gestation and lacta-
tion. The wastelage fed ewes were reported to be in better physical condi-
tion than hay fed control ewes at the end of the second lambing. In addition,
the average daily hay saving per wastelage fed ewe was reported at 0.79 kg.
Moore and Anthony (1970) anaerobically fermented cattle manure with
ammonia and thereby increased the crude protein content from 17.0 to 43.3%
(DM basis). The increase in protein content was mainly the result of in-
creased bacterial protein and ammonium lactate. McClure et^ al. (1973) fed
fermented manure containing straw bedding to steers ad libitum, and the
steers were able to maintain their body weight for 60 days. They also
reported that when manure containing corn stover bedding plus 10% ground
shelled corn was fermented, and additional ground shelled corn was added to
equal the grain in corn silage, average daily gain and dry matter intake
were better than when corn silage was fed alone. When Cereco silage, a
fermented processed feed made from feedlot manure, was fed to steers in a
digestion study, dry matter and crude protein digestion coefficients were
similar to those for cattle fed corn silage (Ward tit al., 1974) . Cereco
silage was as palatable as corn silage when fed as 25 to 50% of the ration.
Chemical Treatment of Manure
A large portion of the undigested feed residues in feces is composed
of cell walls consisting of cellulose, lignin and hemicellulose. If the
cell wall portion of the feces could be made available to the rumen microbes,
then additional nutrients would be available for use by the animal. Maximum
response in improving cell waill digestion was noted when feces was treated
with 3-4% sodium hydroxide or sodium peroxide (as-is basis) in in vitro
studies conducted by Smith et al. (1969). This improvement in cell wall
digestion was the result of chemical solubilization and/or bacterial cell
wall digestion, depending on the substrate. When Smith and coworkers
evaluated chemically treated manure via in vivo studies, they found signifi-
cant improvements in cellulose and hemicellulose digestibilities for the
chemical treated manure as compared to untreated manure. However, nitrogen
digestibility remained unchanged.
When the digestion coefficients for the chemically treated and untreated
feces were calculated, dry matter and cellulose digestibilities doubled, cell
wall digestibility was enhanced four fold and hemicellulose digestibility
was improved ten fold by chemical treatment of the feces. Nitrogen digesti-
bility was improved from 0% for the untreated feces to 18% for the chemically
treated feces. However, the low fecal nitrogen digestibility value suggests
recycling of feces from forage fed animals to be of little value for further
nitrogen utilization.
Smith et al. (1971) reported that the effect of chemical treatment on
feces to be dependent upon the composition of the feces. They observed
higher cell wall digestibility for manure uncpntaminated with sawdust than
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for manure having sawdust bedding and urine contamination. Sawdust influenced
the results in these studies as it was less responsive to chemical treatment
than feces.
Composition of Feces
The dry matter content of cattle manure usually varies from 20-30% as
reported by Anthony (1969, 1971). Values for crude protein content of feces
are reported to range from 13 to 27% by Anthony (1971), Linnimit elt al.
(1972), Johnson et _al. (1972) and Lucas et al. (1975). Anthony (1971) noted
that urea contributes up to 2-4% of the crude protein in feces.
Cell wall content values vary from 22 to 71% on a dry matter basis
(Anthony, 1971, Johnson, 1972 and Lucas et al., 1975). Johnson (1972) and
Lucas et al. (1975) have reported acid detergent fiber to be from 17-45%,
cellulose 16 to 30%, and lignin 5 to 9% on a dry basis. Hemicellulose
content of feces was reported to be 26% by Lucas and coworkers (1975).
Contamination of feces with dust, sand or soil during the collection
process can bias the fecal ash value upward (Johnson, 1972). As a result
of soil contamination, Johnson (1972) reported fecal ash values to be
around 40% while Lucas et al. (1975) and Anthony (1971) reported ash content
to be from 5-12% in feces on a dry basis.
Fecal calcium and phosphorus values on a dry basis range from 0.2 to
0.9% and 0.5 to 1.6%, respectively, as reported by Anthony (1971). Anthony
also found magnesium content to be the highest of all minerals at 0.7 to
3.1%. Potassium ran between 0.5% to 0.9%, and copper, iron, manganese and
zinc were all present in minute amounts.
Feces as a Source of Supplemental Nitrogen
Anthony (1971) found urea to be inferior to wastelage in supplementing
a corn diet. Moreover, Tinnimit et^ al. (1972) found nitrogen retention data
to favor soybean meal over feces as the supplemental source of nitrogen for
lambs, whether intakes were restricted or unrestricted. However, the lambs
fed the feces diets remained in positive nitrogen balance for the four week
trial, and their nitrogen balance and utilization values were remarkably
high (1-5 g of nitrogen retained per day) considering that 40 to 65% of the
dietary nitrogen was of fecal origin. Soybean meal control lambs retained
one to nine grains of nitrogen per day. Lucas and coworkers (1975) observed
higher fecal nitrogen excretions for steers receiving a diet containing 20%
feces as compared to a basal diet even though nitrogen intake favored the
basal ration. This reflects poor nitrogen digestibility of the feces portion
of the ration. As a result, nitrogen retention, expressed as grams per day,
percent of nitrogen intake or percent of absorbed nitrogen was significantly
higher for the basal ration as compared to the feces ration.
Johnson (1975) substituted feedlot feces for the majority of the soy-
bean meal in a standard high concentrate feedlot ration on an iso-nitrogenous
basis and found average daily gain to be reduced and feed to be less
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efficiently utilized for the feces ration as compared to the soybean meal
ration. His results were perhaps influenced, however, by lower intake of
the feces ration.
Feces as a Roughage Source
When feedlot feces were substituted for cottonseed hulls at levels of
25 and 40% in a high roughage ration, ration dry matter digestibilities were
lower for the feces containing rations while organic matter digestibilities
were similar for both basal and feces rations (Johnson, 1972). Nitrogen
digestibilities were consistently higher for the feces ration while ash
digestibilities were lowered by the addition of feces to the rations.
Johnson further reported the theoretical digestibilities of fecal dry matter
and organic matter to be in the range of what many low quality roughages
would be.
In a later study, Johnson jat al. (1975) substituted feedlot waste for
cottonseed hulls in a high concentrate feedlot type ration. The treatments
compared were 1) a control containing 15% cottonseed hulls, 2) feedlot
waste as a total replacement for cottonseed hulls and 3) 10% feces plus 5%
cottonseed hulls. Apparently, feedlot waste in this trial was not a good
roughage source as lamb growth performance data was the poorest for the
lambs receiving feces as a total replacement for cottonseed hulls. The
control fed lambs were the fastest gainers and most efficient feed converters.
Effect of Increasing Levels of Feces in Ration on Ration Digestibility
When dried caged layer feces were incorporated into a standard basal
ration at 20, 40, 60 and 80% levels, and the proportion of corn cobs to
corn starch was held constant, overall ration digestibilities of dry matter
and organic matter decreased linearly with each increasing level of feces
(Tinnimit et al., 1972). Regression equations predicted dry matter and
organic matter digestibilities of dried poultry waste to be 53 and 65%,
respectively.
Albin and Sherrod (1975) compared levels of 0, 20, 40 and 60% of dry
feedlot waste in a high concentrate ration and found a significant linear
decrease in dry matter, organic matter, apparent and true protein, cell
solubles and cell wall ration digestibilities with increasing levels of
feces. The apparent digestion coefficients for feedlot waste increased
linearly with each higher percentage of feces level. The authors suggested
that this could indicate an associative effect between the feces and the
remainder of the ration.
Apparent Digestibility of Nutrients in Feces
Feedlot feces incorporated into low energy-low protein rations were
observed by Albin and Sherrod (1975) to have higher digestion coefficients,
except for cell walls, than feces incorporated into high energy-adequate
protein rations. Differences between the two types of rations in fecal
protein digestibility were the most obvious.
8
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Table 1 shows some apparent digestion coefficients of feces as calculated
by difference.
TABLE 1. THEORETICAL DIGESTIBILITIES AS CALCULATED BY DIFFERENCE FOR FECES
PRODUCED BY ROUGHAGE AND FEEDLOT RATIONS
Source of Feces
Roughage Ration Feedlot Ration
Dry matter
Organic matter
Crude protein
Cell walls
Acid detergent fiber
Cellulose
H mi
16-22a'd
14d
0-26a»d
15-18a'd
5d
12-34a'd
10 28a'd
J-\J £.\J
33-50b'C
35-56b'c
26-71b'C
16-29C
a Smith et al. (1969)
b Johnson (1972)
C Albin and Sherrod (1975)
d Lucas et al. (1975)
Fecal digestion coefficients for all nutrients are consistently higher when
a feedlot type of ration is the source of feces as opposed to feces from a
high roughage ration.
Continuous Recycling of Feces
Anthony (1970) refed cattle manure which was collected from cows that
were fed manure themselves and noted no build-up of indigestible fecal
residues at least as indicated by moisture content. The moisture content
of the feces was higher at the end of the second cycle. However, the
quantitative dry matter output, etc. was not determined. Albin and Sherrod
(1975) reported results of a study by Ferrell and Garrett (1973) in which
their data suggest no increase in fecal minerals and lignin content due to
recycling. They also reported that only about 26% of the dry matter in
manure was digested by recycling on their rations.
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Flegal et al. (1972) studied the effect of long term recycling in
poultry of dehydrated poultry waste on the composition of feces and on bird
performance. Feces were collected for 12 days, dehydrated and refed at levels
of 12.5 and 25% as a replacement for corn in a standard cage laying ration
for 31 successive cycles. The crude protein, crude fiber and ash composition
of the dehydrated poultry waste varied from cycle to cycle, but appeared to
be unrelated to the number of successive cycles. Calcium seemed unrelated
to cycle at the 12.5% level but seemed to increase with each successive
recycling when fed at the 25% level. Fecal phosphorus increased with succes-
sive recycling after about the tenth cycle when feces were fed at either
level. However, after 31 cycles, both feces rations had similar proximate
analyses. Hen housed egg production, daily feed per bird and mortality
figures favored the hens fed the 12.5% dehydrated poultry waste over the
hens fed the control or 25% feces rations. However, all of these values
reflect fecal composition values only and not total fecal output as well.
Differences likely existed in the quantity of fecal output with repeated
cycling.
10
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SECTION V
TRIAL I—RECYCLING DIGESTION TRIAL WITH STEERS
SUMMARY
Faces which were produced on a 90% concentrate ration in phase 1 were
recycled in three consecutive phases (2,3,4) through beef cattle to determine
the effect of feces recycling on the accumulation of indigestible residues
and on nutrient digestibility. Feces from one phase (1,2,3) were refed in
the next phase (2,3,4). In phases 2, 3 and 4, feces (15%) from the previous
phase were then substituted for either all of the roughage (10% cottonseed
hulls, CSH) and 5% corn (Tl) in the basal ration or for 15% of the complete
basal ration fed in phase 1 (T2).
Total indigestible residue excretions increased 60.8% (Tl) to 72.4%
(T2) when feces were recycled the first time. Additional recyclings, how-
ever, produced no further increase in total residue excretion. Excretion
of most fractions, particularly fibrous components, was slightly greater on
T2 than Tl, reflecting the absence of CSH in Tl.
Total ration dry matter digestibility decreased from 85.6% in phase 1
(no feces fed) to 76.1-78.3% in phases 2, 3 and 4, with the values being
only slightly higher (~1%) for Tl than T2 in the three refeeding phases.
Feces appeared to provide an adequate roughage replacement for CSH. Di-
gestibility values for various nutrient parameters in feces (calculated by
difference) when feces were refed in phases 2, 3 and 4 were generally quite
low. Digestibility of the feces increased with each successive recycling,
indicating possible adaptation. Crude protein and ash content of the feces
tended to increase with each recycling.
Recycling feces three consecutive phases reduced the disposable waste
load by 34%. Data in this experiment indicate that feces can be recycled
three times without any material buildup of Na, Cl or P residues. Calcium,
however, showed a definite accumulation. There were no detrimental effects
upon mineral retention when feces were recycled.
INTRODUCTION
Digestion studies with steers were conducted in Trial 1 in which feces
were recycled (refed) in three successive phases. The objectives of this
trial were:
11
-------
1) To determine the influence of recycling beef cattle feces on ration
nutrient digestibility.
2) To determine the accumulation of indigestible residues in feces as
a result of recycling through cattle three consecutive phases.
3) To study the effect on digestibility of replacing the roughage with
feces in a high concentrate ration.
GENERAL PROCEDURES
Experimental Design
The overall experimental design can be depicted graphically as follows:
Phase 1 Phase 2 Phase 3 Phase 4
High concentrate Refed in Refed in Refed in
ration S~*~ ration /**" ration /^" ration
I
Feces Feces —' Feces — Feces
Feces produced in phase 1 were refed in phase 2; that produced in phase
2 were refed in phase 3, etc. A high concentrate ration (Table 2) was fed
in phase 1 to produce feces for refceding in phase 2. Hence, there was only
one treatment in phase 1 (84.0% corn, 10.0% cottonseed hulls, 6.0% supple-
ment). This is termed a basal ration. In this trial, feces were reincorpo-
rated (phase 2,3,4) at a level of 15% (DM basis) in the ration. Since the
ration had a DM digestibility of nearly 85% in phase 1, this represented
nearly complete feces reincorporation, particularly in the early phases.
In phases 2, 3 and 4 there were two treatments as follows:
Tl) Feces (15%) from the previous phase replaced the 10% cottonseed
hulls (CSH), plus 5% corn in the basal ration fed in phase 1.
T2) Feces (15%) replaced 15% of the basal ration fed in phase 1 (i.e.
ration was 85% basal + 15% feces from previous phase).
The ration formulae are shown in Table 2. Since final dry matter (DM) values
differed slightly from the preliminary estimated DM values, the final formulae
actually fed (as shown in Table 2) contained 15.4% feces rather than 15.0%.
The same was true for the other ration ingredients, and this accounts for the
slight difference noted between the desired formulae (15% feces) and those
actually fed (15.4% feces).
Animals Used in Digestion Studies
Twelve Hereford X Angus crossbred yearling steers (approximately 400 kg)
raised in the University herd were selected from a large group on the basis
of uniformity, age and conditioning to establish a "pool" of animals for use
12
-------
in conducting the recycling trials. Due to the time required to complete
these trials, it was necessary to have sufficient steers available to permit
periodic rotation and resting of animals. When steers are maintained in
digestion stalls for prolonged periods, leg problems (swollen and sore knees
and hocks, stiffness, etc.) can develop unless there is an opportunity for
periodic exercise. To permit this, steers were removed from digestion stalls
when it appeared desirable at the termination of a collection period. When
not in the digestion stalls, the steers were maintained on the same ration
but placed in a large, concrete floor pen for at least several weeks. Other
steers from the "pool" of experimental animals could then be rotated or
placed in the digestion stalls for collection purposes during this time.
TABLE 2. COMPOSITION OF RATIONS FED IN TRIAL 1
Ingredient Phase 1 %_
Ground corn, 4-02-935 83.5*^ , ,
Cottonseed hulls, 1-01-599 10."
Supplement^
Soybean meal, 5-04-604
Urea
Wheat middlings, 4-05-205
Calcium carbonate, 6-02-632
Dicalcium phosphate, 6-01-080
Salt, trace mineral
3.6%
0.6%
1.1%
0.6%
0.2%
0.2%
6.3%
6.3^
ration
Phases 2, 3, 4
Ingredient
Ground corn
Cottonseed hulls
Supplement
Feces 3
Tl
%
78.3
6.3
15.4
T2
%
70. 6\
8.6 ?
5.4J
15.4
84.6%
basal
Dry matter basis.
2 3,300 I.U. Vitamin A/kg.
3
Feces from the previous phase.
Procedure for Conducting Digestion Trials
Four steers were selected at random from the pool of steers and assigned
to individual digestion stalls. During phase 1, all four steers were fed the
basal ration for at least 10 weeks to assure an ample supply of feces for the
13
-------
following phases. A one week ration adaptation period was followed by total
daily collections of feces and urine. No feces were saved during adaptation
(first week). Thereafter the feces and urine samples for all four steers
were composited daily and dried in a 60°C forced air oven for 48 hours for
later refeeding. The dried feces were then ground in a hammermill, without
a screen, for incorporation into diets Tl and T2 of phase 2. The urine was
dried to a molasses consistency and stored frozen until needed later in
Trials 3 and 5. Approximately the fourth week, digestion study data were
collected on the four individual steers for a seven day period to ascertain
digestibility. Individual steer outputs of feces and urine were weighed
daily, and 10% of each day's output was frozen in individual containers.
The daily samples were then composited by steer at the end of the 7 days,
and sub-samples were taken and frozen for laboratory analyses.
In phase 2, four more steers were chosen at random from the pool and
used for the remainder of the trial. Two were assigned to each of Tl and
T2 in a switchback design consisting of two periods (see diagram in Figure
1 for illustration). The first period lasted for a period of 4-5 weeks
wherein the procedure was the same as described for phase 1 except composi-
ting of daily fecal collections for refeeding was done by treatment. At
the end of the first period, the steers switched rations so every steer
consumed each of the two rations, giving 4 observations per treatment (Tl
and T2). The second period was handled in the same manner as the first
period. The completion of the second period marked the end of phase 2. As
illustrated in Figure 2, feces from periods 1 and 2 were combined by treat-
ment for refeeding into their respective rations in phase 3. Phases 3 and
4 followed the same procedure as phase 2.
Water was available at all times during the digestion trials. The
steers were fed at a level slightly above maintenance, 2.24 kg per steer
twice per day (total of 4.48 kg DM/day) . There were no feed weighbacks as
the rations were readily consumed by the steers. When steers were reversed
from one treatment to another to complete the switch back design, (Tl-*-T2 or
vice versa) after the completion of a period within a phase, feces were not
saved for later refeeding during the first 5 days for adjustment.
Laboratory Analyses
Dry Matter and Ash
The dry matter content of wet feces was determined by drying approxi-
mately 600 g 6f steer feces from each animal in a forced draft oven at 60°C
to a constant weight (48 hr). The samples were removed from the oven,
allowed to equilibrate with the air for 24 hr and then reweighed. The steer
feces were ground through a 1 mm screen in a large Wiley mill. Dry matter
was determined on a two gram sample of the ground feces, and the 100% dry
matter of the wet feces was thus calculated by multiplying the two dry
matters. The two gram dry matter sample was then ashed in a 600°C furnace
for four hours and reweighed. The residue in the crucibles was digested
in 20% hydrochloric acid and diluted to volume with demineralized water for
mineral analysis (Na, Ca, Cl). Dry matter and ash on the rations were
determined by AOAC (1965) procedures.
14
-------
Phose I
Basel
1,2,3,4
Phose 2
Phase 3
Phose 4
i
1,2,3,4
Feces
Composite
EH
' t *
Tl TO
1 1 C
1 5,6 7,8
2 7,8 5,6
1 1
,7,8 7,8,5,6
eces T2 Feces
josite Composite
t
I
t
j
\
\
J t
k
i
*- ^ T
* X 1
Per 1 5,
Per 2 6,
I
5,7,6,8
Tl Feces
Composite
* .
t
T O
1 C
1 6,8
8 5,7
v
6,8,5,7
T2 Fecet
Composit
T2
Per I 6,7 5,8
Per 2 5,8 6,7
FIGURE 1. SCHEMATIC DIAGRAM OF THE EXPERIMENTAL DESIGN USED IN TRIAL 1. Numbers 1 to 8
represent steers. Per=period within a phase used for switchback purposes.
-------
Crude Protein
Crude protein was determined on rations, urine, and dried feces accord-
ing to AOAC (1965) methods. Crude protein was also determined on wet steer
feces by placing an 80 g sample of wet feces in a Waring blender along with
250 ml of water and blending for two minutes. Duplicate ten gram samples
of the homogenate were analyzed for nitrogen content by the Kjeldahl pro-
cedure. Dry matter was also determined on the homogenate. Since the crude
protein values on the wet steer feces were consistently higher (approximate-
ly 10%) than on the dried steer feces, the values on the wet steer feces
were used in determining the crude protein digestion coefficients.
Fiber
Acid-detergent fiber (Van Soest, 1963), lignin and cellulose (Van Soest
and Wine, 1968) were determined on rations and dried feces. Total cell walls
(NDF ) were determined by a modification of the Van Soest and Wine (1967)
procedure. Ashless filter paper (Whatman #541) was used instead of the
recommended Gooch crucible for filtering NDF's due to the filtering diffi-
culty encountered with the feces samples.
Minerals
Calcium and sodium were determined on the acid-digested ash samples
using an atomic absorption spectrophotometer. Phosphorus was determined
on a color spectrophotometer using ammonium molybdate as a color developer.
Chlorine was analyzed according to AOAC (1965) methods. Calcium analysis
in Trial 1 showed that most, 99%+, of the calcium excretion to be in the
feces, thus, making accurate calcium determinations in the urine difficult,
if not impossible and totally meaningless.
Calculations
Apparent digestibilities of dry matter, organic matter, crude protein,
cell walls, acid-detergent fiber, lignin and cellulose in dried steer feces
were calculated by-difference (Crampton and Harris, 1969). The by-differ-
ence method assumes in the calculations that the digestibility of the basal
portion of the ration (ration component other than feces) remains the same
when feces are included as when the basal ration is fed alone. That is to
say, if a basal ration has a digestibility of 80% when fed alone, the basal
ration component is assumed to still have a digestibility of 80% when fed
with feces. Thus, if a ration contained 90% basal + 10% feces, the digesti-
bility contribution from the basal portion would be 72% (90% X 80% = 72%).
Coefficients of digestion were calculated in the conventional manner (i.e.
Intake-excretion/intake X 100 = % digestibility).
Statistical Analyses
The data were analyzed by analysis of variance and differences among
means were tested by the least significant difference test (Snedecor and
Cochran, 1967).
16
-------
RESULTS AND DISCUSSION
Digestibilities of Complete Rations
Dry Matter
Ration dry matter digestibility decreased from 85.6% for the basal
ration in phase 1 to 76.8% and 75.4%, for Tl and 12, respectively, in phase
2 (Table 3). In each consecutive phase (2,3,4), a slightly higher dry
matter digestibility was obtained (P>.05) within each treatment. Moreover,
in every phase, dry matter digestibility for Tl was slightly higher (P>.05)
than for T2, averaging 77.7 for Tl vs 76.6% for T2 in the three phases. The
slightly lower digestibilities observed for T2 can be attributed to the
presence of 8.5% CSH in T2 vs_ 0% in Tl. Interestingly, the differences might
have been anticipated to be greater than actually observed. Recall that
feces replaced CSH as the roughage source in Tl and appeared to provide an
adequate roughage replacement.
Organic Matter
The inclusion of feces into the basal ration resulted in a decrease of
approximately 9% in organic matter digestibility (Table 3). However, as
with dry matter, organic matter digestibility increased slightly (P>.05)
with each additional recycling of feces. No significant differences (P>.05)
were observed between treatments within a phase or among phases within a
treatment.
Ash
Ash digestibility in phase 2 was 44.9 (Tl) and 42.9% (T2), as compared
to 57.2% for the basal in phase 1 (Table 3). This is a net reduction of
21.5 (Tl) and 25.0% (T2) in ash digestibility after the first recycling of
feces. Within each treatment, ash digestibilities increased (P>.05) with
each additional recycling of feces after the first. Differences between
treatments within a phase were not significant. Such a percentage reduction
can be accounted for largely by the increased total mineral intake in that
net retention expressed on a gram or quantity basis remained about the same
as in phase 1.
Crude Protein
Although not significant, crude protein digestibility was slightly
higher for Tl than T2 in every phase (Table 3). Phase differences within
each treatment were not significant for protein digestibility. The first
recycling of feces resulted in a decrease of 12.8 and 14.7% in crude pro-
tein digestibility for Tl and T2, respectively as compared to the basal
ration. The average protein digestibility for phases 2 thru 4 was approxi-
mately 58% vs 68.2% in phase 1.
Acid Detergent Fiber
Acid detergent fiber (ADF) digestibility was markedly lower (45.5%) for
Tl in phase 2 as compared to the basal ration (Table 4). Also, in phase 2
ADF digestibility for T2 was 24.5% less than for the basal ration. ADF
digestibility for Tl decreased from 28.7% in phase 2 to 19.5% in phase 4,
while T2 increased from 39.8% to 45.0% over the same period. In phases
2, 3, and 4, ADF digestibilities were higher for T2 than for Tl (39.8% vs
17
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TABLE 3. APPARENT RATION DIGESTIBILITIES OF DRY MATTER,
ASH AND CRUDE PROTEIN IN TRIAL 1
2 3
Dry matter *
Organic matter
Ash
Crude protein
Phase 1
2
3
4
Phase 1
2
3
4
Phase 1
2
3
4
Phase 1
2
3
4
Rations
Basal Tl
85.6
76.8
77.6
78.8
SEM 1.5
86.8
78.7
79.6
80.4
SEM 1.6
57.2
44.9
45.2
50.1
SEM 3.3
68.2
59.5
61.4
59.8
SEM 1.8
T2
75.4
76.7
77.8
0.7
77.2
78.3
82.8
0.6
42.9
49.8
52.8
4.7
58.2
55.8
57.1
2.3
Means
85.6
76.1
77.2
78.3
86.8
78.0
79.0
81.6
57.2
43.9
47.5
51.4
68.2
58.8
58.6
58.4
1
SEM
1.3
1.4
1.1
1.2
1.3
1.1
3.5
2.6
2.4
2.4
1.7
1.5
Standard error treatment mean.
2 Phase 1 was not included in the statistical analyses.
Values represent the mean of four observations per treatment.
28.7%, 42.3% vs 24.8% and 45.0% vs 19.5%) reflecting the presence of CSH in
the ration. These differences were significant (P<.05) in phases 3 and 4.
Lignin
There were no differences (P>.05) between treatments within a phase or
among phases within a treatment in lignin digestibilities (Table 4). The
addition of feces to the ration decreased lignin digestibility from 52.3%
18
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TABLE 4. APPARENT RATION DIGESTIBILITIES OF ACID-DETERGENT
FIBER, LIGNIN, CELLULOSE AND NEUTRAL DETERGENT
FIBER IN TRIAL 1
ADF1'2'3
Lignin
Cellulose
NDF
Phase 1
2
3
4
Phase 1
2
3
4
Phase 1
2
3
4
Phase 1
2
3
4
Rations
Basal Tl
52.7
28.7
24. 8a
19. 5a
SEM 4.3
52.3
33.5
38.1
36.7
SEM 2.5
62.7
34.6
37.2
33. 8a
SEM 4.8
77.8
63.5
65.6
64.6
SEM
T2
39.8
42. 3b
45. Ob
2.0
38.0
39.3
39.5
1.2
47.6
51.1
55. 6b
2.3
66.7
66.9
67.7
Means
52.7
34.2
33.6
32.2
52.3
35.8
38.7
38.1
62.7
41.1
44.2
44.7
77.8
65.1
66.2
66.2
SEM
3.7
3.7
3.6
3.5
3.6
3.4
4.3
3.7
2.9
3.2
2.1
1.8
Phase 1 was not included in the statistical analyses.
>a* Values within phase with different superscripts differ significantly
(P<.05).
3
Values represent the mean of four observations.
for the basal ration to 33.5% for Tl and 38.0% for T2 in phase 2. T2 tended
to have slightly higher lignin digestibilities than Tl in every phase, again
reflecting the presence of CSH.
19
-------
Cellulose
Cellulose digestibility was higher in T2 than Tl in every phase by
approximately 13-18% with the difference being significant (P<.05) in phase
4 (Table 4). Cellulose digestibilities were 34.6% and 47.6% for Tl and T2,
respectively, as compared to 62.7% for the basal ration. This is a decrease
in cellulose digestibility of 44.8% for Tl and 24.1% for T2. The second
and third recyclings of feces produced no significant change in cellulose
digestibility for Tl or T2.
Neutral Detergent Fiber
Neutral detergent fiber (NDF) favored (P>.05) T2 over Tl in every phase
(Table 4). The first recycling of feces reduced NDF digestibility by 18.4%
for Tl and 14.3% for T2. No differences (P>.05) were noted among phases 2,
3 and 4 within either treatment.
Average of Treatments by Phase
Since phase X treatment was not significant for any of the parameters,
digestion coefficients for Tl and T2 were averaged for each phase (Table 3).
Digestion coefficients for all the nutrients were lower in phase 2 as com-
pared to phase 1. When averaged across treatments, ration digestibilities
increased slightly with the first, second and third recycling of feces as
follows: dry matter—76.1, 77.2 and 78.3%; organic matter—78.0, 79.0 and
81.6%; and ash—43.9, 47.5 and 51.4%. Crude protein digestibilities for
the rations were about 58% during all three recycling phases. Lignin,
cellulose and NDF digestibilities showed a similar pattern. It appears
that perhaps some gradual adaptation to improved digestion of feces occurred
with prolonged feeding. Ferrell and Garrett (1973) reported that the more
digestible nutrients in a 50% feces ration tended to decrease during re-
cycling while the less digestible components tended to increase.
Apparent Digestibility of Fecal Nutrients
There was a calculated disappearance of 19% for fecal dry matter with
one recycling (Table 5). Similar values have been reported by Lucas et al.
(1975) and Smith et al. (1971) for dry matter digestibility of feces when
feces were included at 20 and 25%, respectively, in high roughage rations.
Albin and Sherrod (1975) observed that about 33% of the dry matter in manure
disappeared with one recycling when manure constituted 40% of a feedlot
ration for cattle. However, they stated that digestion coefficients for
fecal nutrients were lower when feces were refed at a level of 20% than 40%
in the ration; similarly inclusion at a 60% level produced higher dis-
appearance values than the 40% level. This suggests an associative effect.
Dry matter digestibility of the feces in phases 3 and 4 was slightly higher,
but still rather low being 27.7 and 34.3%, respectively. Thus in this
experiment, after 3 recyclings, the amount of disposable manure would appear
to be reduced by approximately one-third. Ferrell and Garrett (1973) refed
cattle manure at a level of 50% in a high roughage pelleted ration and
reported dry matter digestibilities for manure to be 26.6, 15.1 and 15.7%
during the first, second and third recycling of manure, respectively. The
differences in trends may be attributed to numerous variables, including
the type of ration into which feces were incorporated—e.g., high roughage
vs high concentrate.
20
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TABLE 5. APPARENT DIGESTION COEFFICIENTS FOR CATTLE FEEDLOT
WASTE—CALCULATED BY DIFFERENCE
Number of recyclings
PH 2
1
PH 3
2
PH 4
3
Means
Apparent digestibilities:'
Dry matter
Organic matter
Ash
Crude protein
ADF
Lignin
Cellulose
NDF
19.0
24.9
-35.5
3.7
-31.3
-40.7
-35.4
5.6
27.7
31.4
9.1
-12.2
-14.6
-31.7
-12.5
7.1
34.3
60.6
28.6
-4.9
2.0
-31.9
15.7
11.4
27.0
39.0
0.7
-3.2
-14.6
-34.7
-10.7
8.0
Calculated by difference as outlined by Crampton and Harris (1969).
All fecal nutrients, except crude protein and lignin, showed increased
digestibility with each successive recycling of feces. This increase in
digestibility of fecal components for each successive recycling of feces
could indicate that the rumen microbes are undergoing some sort of adaptation
over time in response to the presence of feces in the ration. However,
traditionally any adaptation response would be expected to occur much more
rapidly. For the most part, digestion coefficients were low for all nutrient
parameters in the feces. The negative digestibilities that appear in the
table for some items were unexpected and perhaps suggest a negative associ-
ative effect between feces and the remainder of the ration.
The low digestibility values for crude protein in feces in this experi-
ment suggest limited potential for feces as a supplemental protein source
in feedlot rations. However, the urine was not included and may effect the
results in that manure normally includes nitrogen or protein contributions
from both feces and urine.
Composition of Feces
The dry matter content of feces as excreted in Trial 1 ranged from
23.4% to 25.7% (Table 6) and showed little difference with recycling. The
21
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ash content of feces tended to be several percent higher when the ration
contained feces (phases 2,3,4) than when it did not (phase 1). The crude
protein content of feces also tended to increase somewhat in each recycling
phase (average of 22.2% in phase 2 vs 25.6% in phase 4).
The percent sodium in the feces produced by steers consuming feces
(phases 2,3,4) was lower (0.11 to 0.24%) than in the feces produced by
steers fed the basal ration (0.42%). Although the differences were small,
chlorine content of feces, on the other hand, was higher in refeeding phases
2, 3, and 4 than with the basal ration (phase 1). Calcium content in feces
tended to be higher when feces were recycled, and phosphorus lower than in
phase 1. However, one must remember that the percentage composition is
also a function of output when considering total residue excretion. Total
residue excretions are presented later.
Composition of Urine
The percent crude protein in urine was slightly higher for T2 than for
Tl in all phases (Table 7) with the average content being approximately 4%.
Although the urinary sodium content on both Tl and T2 was higher in phase
2 than for the basal in phase 1 (0.18 vs 0.10%), the urinary sodium level
decreased in phases 3 and 4 (0.12 and 0.10%, respectively) which were similar
to those in phase 1. Chlorine content in urine was highest for steers fed
the basal ration (0.54%) and declined with each successive recycling of
feces in each treatment (0.21 to 0.14% for Tl and 0.26 to 0.15% for T2).
The percent phosphorus in urine for the basal ration was 0.08%. In phases
2, 3 and 4, the respective values were: 0.17, 0.15, 0.07% for Tl and 0.23,
0.15 and 0.11% for T2.
Residue Excretions
The total indigestible fecal dry matter produced daily on the basal
ration was 575.2 g compared to an average of 925.2 g (Tl) and 991.4 g (T2)
in phase 2 (Table 8). This represents an increase of 60.8% for Tl and 72.4%
for T2 in indigestible dry matter excretion when feces are recycled once.
The second and third recyclings (phases 3 and 4) resulted in a slight de-
crease in the accumulation of total indigestible residues.
The first recycling of feces resulted in a 40-90% increase over the
basal ration in the accumulation of indigestible ash, ADF, lignin, cellulose
and NDF residues, with the increase being larger for T2 than Tl, particularly
for all of the fiber fractions. This observation can be explained by the
absence of CSH in the Tl ration. As with dry matter, the accumulation of
indigestible residues associated with the second and third recyclings of
feces (phases 3 and 4, respectively) tended to either remain stable or to
decline as compared to the first recycling (phase 2). The large increases
in indigestible residues when feces are recycled confirms the rather low
digestibilities noted for the various fecal fractions. However, a portion
of the feces are digested when recycled as evidenced by the fact that in-
digestible residues did not double when there was essentially complete fecal
reincorporation. Moreover, the general decrease in total daily indigestible
residue excretions from phases 2 through 4 suggest some adaptation to fecal
22
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TABLE 6. COMPOSITION OF FECES IN TRIAL 1
Rations
1 2
Dry matter '
Ash
Crude protein
ADF
Lignin
Cellulose
NDF
Sodium
Chlorine
Basal
Phase 1 25.7
2
3
4
Phase 1 11.5
2
3
4
Phase 1 24.4
2
3
4
Phase 1 32.1
2
3
4
Phase 1 11.7
2
3
4
Phase 1 21.0
2
3
4
Phase 1 48.8
2
3
4
Phase 1 0.42
2
3
4
Phase 1 0.20
2
3
4
Tl
25.0
25.8
23.4
13.4
13.9
12.8
23.1
23.5
25.0
28.8
26.4
28.9
11.8
10.4
10.8
18.2
15.3
16.6
45.0
42.3
46.4
0.24
0.11
0.18
0.23
0.25
0.23
T2
24.2
24.6
24.5
12.6
11.6
12.6
21.2
24.3
26.1
34.9
34.8
31.6
12.8
13.8
13.1
21.9
21.2
18.2
46.8
48.7
44.9
0.18
0.14
0.20
0.28
0.26
0.24
Means
24.6
25.2
24.0
13.0
12.8
12.7
22.2
23.9
25.6
31.8
30.6
29.8
12.3
12.1
12.0
20.0
18.2
17.4
45.9
45.5
45.6
0.21
0.12
0.19
0.26
0.26
0.24
Table continued
23
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TABLE 6 (Cont'd). COMPOSITION OF FECES IN TRIAL 1
Rations
Calcium Phase
Phosphorus Phase
All nutrients, except
2
Values represent the
TABLE
Rations
Crude protein Phase
Sodium Phase
Chlorine Phase
Phosphorus Phase
Basal
1 2.22
2
3
4
1 1.10
2
3
4
dry matter,
mean of four
Tl
2.52
2.59
2.63
1.04
0.90
0.88
are on a 100%
observations
T2
2.24
2.15
2.69
0.91
0.77
1.07
dry matter basis.
per treatment.
Means
2.38
2.37
2.66
0.98
0.84
0.98
7. COMPOSITION OF URINE IN TRIAL 1
Basal
1 3.90
2
3
4
1 0.10
2
3
4
1 0.54
2
3
4
1 0.08
2
3
4
Tl
3.87
4.25
2.84
0.18
0.13
0.07
0.21
0.20
0.14
0.17
0.15
0.07
T2
4.34
4.29
4.90
0.17
0.10
0.14
0.26
0.17
0.15
0.23
0.15
0.11
Means
4.10
4.27
3.87
0.18
0.12
0.10
0.24
0.18
0.14
0.20
0.15
0.09
Values represent the mean of four observations per treatment.
24
-------
digestion or a diminishing of negative associative effects. However, the
indigestible nutrients (Table 8) in the rations containing feces were always
higher than in the basal ration. Indigestible dry matter, ADF, lignin,
cellulose and NDF were higher in T2 than in Tl for every phase. This is
related to the presence of cottonseed hulls in T2 and their absence in Tl.
Cottonseed hulls are rather indigestible due to a high cell wall content
which is measured by ADF (ADF values include lignin and cellulose content
of cell walls) and NDF values.
TABLE 8. INDIGESTIBLE FECAL RESIDUES IN TRIAL 1
Rations Basal Tl T2
Dry matter
Ash
ADF
Lignin
Cellulose
NDF
Phase 1 575.2
2
3
4
Phase 1 65.9
2
3
4
Phase 1 184.2
2
3
4
Phase 1 66.9
2
3
4
Phase 1 121.0
2
3
4
Phase 1 208.2
2
3
4
g/day
925.2
898.3
854.3
122.9
124.7
108.2
265.2
236.7
238.5
108.4
93.6
92.3
169.0
137.5
141.6
418.9
380.3
395.8
991.4
932.4
890.6
125.1
108.3
102.4
345.7
324.7
304.2
126.2
128.3
126.5
217.6
197.5
177.4
465.2
454.7
438.2
Values represent the mean of four observations per treatment.
Crude protein, sodium (Na), chlorine (Cl), calcium (Ca) and phosphorus
(P) are nutrients which are excreted in the feces and urine (Table 9). Crude
protein excreted in the feces was 141.0 g per day for steers fed the basal
25
-------
ration as compared to fecal excretions of 212.4 (Tl) and 210.4 g (T2) in
phase 2. Daily urinary excretions of protein in phase 2 were 171.7 (Tl) and
165.9 g (T2) vs 191.0 g on the basal ration (phase 1). The lower urinary ex-
cretions in phase 2 reflect the lower ration protein digestibilities when
feces were fed. Thus, the total excretion of protein (feces and urine) after
one recycling was higher for both Tl (15.7%) and T2 (13.3%) than for the
basal ration. In general, total excretion of protein continued to rise still
further during phases 3 and 4, again reflecting the low protein digestibility
in the recycled feces.
TABLE 9. RESIDUES FROM TRIAL 1 EXCRETED IN THE FECES AND URINE
Phase
Basal
Feces Urine Total
1 141.0 191.0 332.0
2
3
4
Feces
Crude !
212.4
210.6
213.4
Tl
T2
Urine
-g/da
Prote
171.
259.
188.
y
in
7
4
9
Total
1
384.
470.
402.
1
0
3
Feces
210.
225.
219.
4
8
7
Urine
165
225
257
.9
.5
.8
Total
376.3
451.3
477.5
Sodium
Phase
1 2.4 6.4 8.8
2
3
4
2.0
1.0
1.5
7.
7.
4.
9
9
6
9.9
8.
6.
9
1
1.
1.
1.
8
3
6
5
6
7
.5
.3
.6
7.3
7.6
9.2
Chlorine
Phase
1 1.2 29.5 30.7
2
3
4
2.2
2.2
1.9
9.
12.
10.
2
9
0
11.
15.
11.
4
1
9
2.
2.
1.
8
4
9
10
10
8
.3
.1
.2
13.1
12.5
10.1
Calcium
Phase
1 12.8 0.4 13.2
2
3
4
23.2
23.1
22.4
0.
0.
0.
0
0
0
23
23
22
.2
.1
.4
22.
20.
19.
3
0
0
0
0
0
.0
.0
.0
22.3
20.0
19.0
Phosphorus^
Phase
1 6.4 6.9 13.3
2
3
4
9.6
8.2
7.4
7.
7.
4.
2
8
3
16
16
11
.8
.0
.7
8.
7.
6.
9
1
9
8
7
5
.2
.9
.2
17.1
15.0
12.1
Values represent the mean of four observations per treatment.
26
-------
Sodium and chlorine excretions occur mainly in the urine while Ca is
excreted almost entirely in the feces. Phosphorus is excreted about equally
via the urine and feces. In general, total Na excretion showed little
change during recycling. Total Na excretion rose slightly in phase 2 on Tl
from 8.8 to 9.9 g per day, but declined on T2 from 8.8 to 7.3 g per day.
Total Cl excretion, however, decreased markedly (in excess of 50%) in phases
2, 3 and 4 compared to phase 1. All of the feces-containing rations had
less total excretion of Cl than the basal ration. This may have been in-
fluenced by the presence of only feces and not urine (source of most Cl
excretion) in phases 2, 3 and 4. However, the decreases appear much larger
than anticipated since only 15% feces were incorporated in the ration.
Steers fed the basal ration excreted a total of 13.2 g of Ca per day
as compared to total excretions of 23.2 and 22.3 g per day for steers fed
Tl and T2, respectively in phase 2. Additional recyclings of feces (phases
3 and 4) produced no further build-up of Ca. Ca levels in urine are very
low and difficult, if not impossible, to quantify.
Phosphorus excretions in both the feces and urine rose when feces were
recycled the first time. However, at the end of the third recycling, total
P excretion was nearly the same (approximately 12 g) as that observed on the
basal ration in phase 1 (13.3 g).
The data in this experiment indicate that feces can be recycled three
times without any material build-up of Na, Cl or P residues. Phosphorus
residues were higher after the first recycling but lower after the third as
compared to the basal. However, more recyclings (phases) would be helpful
in determining P build-up in the residues. Calcium was the only mineral to
show a definite accumulation with recycling. Refeeding both the feces and
urine might have altered the mineral excretion patterns for Na, Cl and P.
Mineral Retention
Sodium (Table 10), chlorine (Table 11), calcium (Table 12) and phos-
phorus (Table 13) retention data showed no particular trends and no signi-
ficant differences either between treatments within phase or across phases
when feces were recycled. The large negative chlorine retention observed
during phase 1 (basal ration fed) is questionable. In general, the daily
net mineral retention values were small and averaged approximately 1.62 g
for Na, 1.52 g for Cl, 7.09 g for Ca and 0.18 g for P. These retention
figures represented approximately 16.4% of the mineral intake for Na, 10.6%
for Cl, 25.7% for Ca and 1.2% for P. In general, there appeared to be no
detrimental-effects upon mineral retention when feces were recycled.
27
-------
TABLE 10. UTILIZATION OF SODIUM IN TRIAL 1
Phase 1
Phase 2, Tl
Phase 2, T2
Phase 3, Tl
Phase 3, T2
Phase 4, Tl
Phase 4, T2
SEM for Tl:1.7
SEM for T2:1.0
Phase 1 was not
2
Values represent
Intake
10.03
9.13
10.89
10.42
9.24
10.34
9.18
included
the mean
Fecal Urine Net
Excretion Excretion Retention
2.40
2.04
1.81
1.02
1.34
1.50
1.60
— g/day
6.37
7.94
5.54
7.93
6.28
4.60
7.55
1.261'2
-0.85
3.54
1.47
1.62
4.24
0.03
SEM
1.5
1.5
1.5
1.5
1.3
1.3
in the statistical analyses.
of four observations.
TABLE 11. UTILIZATION OF
Phase 1
Phase 2, Tl
Phase 2, T2
Phase 3, Tl
Phase 3, T2
Phase 4, Tl
Phase 4, T2
SEM for Tl:2.0
SEM for T2:1.3
Intake
13.87
15.02
13.60
15.00
13.98
14.89
13.42
Fecal
Excretion
1.15
2.15
2.76
2.17
2.44
1.94
1.87
CHLORINE IN TRIAL
Urine
Excretion
g/day
29.52
9.18
10.30
12.90
10.07
10.05
8.17
1
Net
Retention
-16. 801'2
3.69
0.54
-0.07
1.47
2.90
3.38
SEM
0.6
0.6
1.8
1.8
1.2
1.2
Phase 1 was not included in the statistical analyses.
fy
Values represent the mean of four observations.
28
-------
TABLE 12. UTILIZATION OF CALCIUM IN TRIAL 1
Phase 1
Phase 2, Tl
Phase 2, T2
Phase 3, Tl
Phase 3, T2
Phase 4, Tl
Phase 4, T2
SEM for Tl:1.5
SEM for T2:1.8
Phase 1 was not
2
Values represent
Intake
17.79
26.67
24.95
32.54
28.05
30.73
32.12
included
the mean
Fecal
Excretion
12.75
23.20
22.34
23.12
19.97
22.40
18.95
Urine
Excretion
— g/day -
0.41
0.01
0.01
0.01
0.02
0.01
Net
Retention
4.631'2
3.46
2.61
9.41
8.07
8.31
13.16
SEM
2.1
2.1
0.3
0.3
2.5
2.5
in the statistical analyses.
of four observations.
TABLE 13. UTILIZATION OF PHOSPHORUS IN TRIAL 1
Phase 1
Phase 2, Tl
Phase 2, T2
Phase 3, Tl
Phase 3, T2
Phase 4, Tl
Phase 4, T2
SEM for Tl:0.8
SEM for T2:1.5
Intake
12.42
16.75
15.94
14.08
14.58
14.77
15.01
Fecal
Excretion
6.40
9.60
8.94
8.25
7.14
7.45
6.93
Urine
Excretion
— — o/rlrj-iT
••g/aay--
6.92
7.15
8.24
7.83
7.94
4.34
5.17
Net
Retention
-0.901'2
0.00
-1.24
-2.00
-0.50
2.98
2.91
SEM
0.3
0.3
1.2
1.2
1.6
1.6
Phase 1 was not included in the statistical analyses.
Values represent the mean of four observations.
29
-------
SECTION VI
TRIAL 2—RECYCLING DIGESTION TRIAL WITH STEERS
SUMMARY
Recycling studies were conducted with steers to determine the influence
of roughage level (0, 7, 14, 21% Cottonseed hulls, CSH) in high concentrate
rations on digestibility and accumulation of indigestible residues when
feces were recycled from such rations in three successive phases. Feces were
reincorporated in each successive phase (2,3,4) based upon the percent of
feces dry matter voided on each treatment in the previous phase (1,2,3).
In each treatment (0, 7, 14, 21% CSH), feces replaced an equal amount of the
complete basal ration which was fed in phase 1-providing complete feces re-
incorporation in phases 2, 3 and 4.
Ration DM digestibility in phase 1 (no feces fed) was nearly identical
(~85.6%) on the 0, 7 and 14% CSH rations, suggesting strong favorable as-
sociative digestibility effects for low levels of CSH. However, digestibil-
ity was lower, 82.1%, on the 21% CSH ration. Declines in digestibility with
feces reincorporation were less pronounced than in Trial 1. The total
ration DM digestibilities averaged across all four treatments were 84.8,
82.5, 78.6 and 80.3% in phases 1, 2, 3 and 4, respectively.
In general, feces had a low to moderate, but variable digestibility
when refed. Feces appeared to have roughage associative effects on digesti-
bility when the ration contained 0% CSH. Calculated digestibility values
for the refed or recycled feces fraction, averaged across all four treat-
ments and refeeding phases (2,3,4), was 60.8% for dry matter, 64.5% for
organic matter, 31.6% for ash, 41.7% for crude protein and 42.8% for acid
detergent fiber. Digestibility of fiber components tended to increase with
each successive recycling.
In general, the composition of the feces produced changed from phase
1 to 4 such that there was a small, but consistent increase on the order of
2-4% in the dry matter, ash, protein and fiber content. Phase 2 (first re-
cycling) produced a 15% increase in total residue excretions over phase 1;
in phase 3, residue excretion showed a further rise of 21% over phase 2;
phase 4 showed no further increase. As in Trial 1, feces recycling produced
no material buildup of Na, Cl or P, but produced an accumulation of Ca.
Inclusion of urine in the diet may have altered the results for Na, Cl and/
or P. Recycling produced normal mineral retention values.
30
-------
INTRODUCTION
Digestion studies were conducted in this trial to determine the effect
of variable roughage levels (0, 7, 14, 21%) in high concentrate rations on
ration digestibility and on the accumulation of indigestible residues when
feces were recycled from such rations three times. The quantity of feces
reincorporated in each recycling period was based upon the amount voided in
the previous phase (total reincorporation, not a constant level of 15% as
in recycling Trial 1).
GENERAL PROCEDURES
Experimental Design
The overall experimental design in this trial was somewhat similar to
that in Trial 1 as depicted by the following:
Phase 1 Phase 2 Phase 3
High concentrate Refed in Refed in
ration S? ration /^ ration
1
Feces Feces Feces Feces
There were 4 treatments in each phase. The major ways in which the design
in Trial 2 differed from Trial 1 were:
1) There were 4 treatments (roughage levels of 0, 7, 14, 21% cotton-
seed hulls) in phase 1 as follows:
TI T£ 13 14
0 7 14 21\
4 87 80 73 >
6 _ 6_ _ 6_ _ 6_ }
CSH
Corn 94 87 80 73 > Referred to as basal
Supp _ 6 _ 6_ _ 6_ _ 6_ } rations
100 100 100 100
2) Feces were reincorporated into the 4 basal rations (treatments
T1-*T4) in phases 2, 3 and 4 based upon the amount of feces voided
in the previous phase as follows:
Phases 2, 3 and 4
% Basal (basal rations same as in phase 1 for T1-KT4)
+
% Feces (based on % voided in previous phase)
As noted above, feces simply replaced a corresponding percentage of the
basal ration. Therefore, the level of feces in the rations was not con-
stant from phase to phase as in Trial 1. As in Trial 1, the actual formulae
fed (Table 14) in phase 1 differed only slightly from the 0, 7, 14, 21% CSH
31
-------
levels intended due to the fact that the final dry matter values of the feeds
actually fed differed slightly from the preliminary dry matter estimates.
TABLE 14. COMPOSITION OF RATIONS FED IN TRIAL 2
Rations*
Tl
0
T2
7
T3
14
T4
21
Phase 1 (Basal)
Ground corn, 4-02-935
Cottonseed
Supplement
hulls, 1-01-599
Basal
Feces^
Basal
Feces
Basal
Feces
93.8
6.2
Phase 2
85.3
14.7
Phase 3
85.5
14.5
Phase 4
80.9
19.1
86.7
7.1
6.2
86.1
13.9
84.4
15.6
80.0
20.0
79.6
14.2
6.2
86.0
14.0
83.0
17.0
78.3
21.7
72.5
21.3
6.2
82.7
17.3
79.0
21.0
74.0
26.0
Dry matter basis.
o
Percent reincorporation was equal to the percent voided in the previous
phase for each respective ration.
Procedure for Conducting Digestion Trials
Eight steers were randomly chosen from the same pool of steers used in
Trial 1 and randomly assigned to the four treatments in phase 1, giving 2
steers/treatment. Due to a limitation on available collection facilities
not more than 8 digestion trials (2 animals/treatment) could be conducted
simultaneously. All steers were accustomed to digestion stalls and a feces
diet, permitting rotation to digestion stall or diet when desirable. Each
phase (except phase 2) consisted of three periods, and each period had two
steers/treatment to give a total of six observations/treatment within each
phase. There were only 2 periods in phase 2, however, giving 4 observations
per treatment. This was because the original intent was to obtain only 4
observations per treatment in phases 2, 3 and 4. Later, this was revised
in phases 3 and 4 when it was apparent that sufficient feces were available
to obtain 2 additional observations/treatment. Steers were rerandomized at
the end of each period. During the first 5 days of each period (within a
32
-------
phase) feces were not saved for future refeeding (to allow for adjustment).
Thus, each succeeding phase was somewhat shorter than the previous due to
the fact that feces produced during the adjustment periods could not be
saved for later refeeding. Each period was usually a minimum of four to
five weeks to permit ample feces production for refeeding in succeeding
phases. Digestion trials were conducted near the completion of each period
after cattle had been on the specific ration for several weeks. The steers
were fed as in Trial 1. Rations were consumed readily, and there were no
feed weighbacks.
Sample Collection and Laboratory Analyses
Methods of collecting and drying feces and urine for refeeding (urine
dried for later use in Trials 3 and 5), sampling procedures for feces and
urine, laboratory analyses, calculations and statistical analyses were the
same as reported in Trial 1.
RESULTS AND DISCUSSION
Digestibilities of Complete Rations
Dry Matter
Apparent dry matter digestion coefficients (Table 15) in phase 1 for
the 0, 7, 14, and 21% CSH basal rations were 84.9, 86.5, 85.5 and 82.1%,
respectively. Since CSH normally have a rather low digestibility (about
one-half of corn or less), the dry matter digestibility of a complete ration
should, in theory, decrease as the level of CSH increases. Interestingly,
the DM digestibilities were essentially identical for the 0, 7 and 14%
CSH diets, suggesting strong favorable associative effects on enhanced di-
gestibility for low levels of CSH. Possibly the rate of passage is reduced
by low levels of CSH, increasing digestive efficiency. When feces were added
to the basal ration (phase 2), dry matter digestibility for Tl (0% CSH) re-
mained the same as in phase 1, while dry matter digestibility for T2, T3
and T4 decreased from 2.6 to 3.6%. Small additional decreases ranging from
0.5-5.4% were observed in phases 3 and 4. In general, T4 always had the
lowest digestibility in all phases (P<.05 in phases 2, 3 and 4). This can
be attributed to the high CSH level. Again, the differences were smaller
than anticipated for the Tl, T2 and T3 rations. When averaged across all
four treatments (within a phase), the average DM digestibilities were 84.8,
82.5, 78.6 and 80.3% in phases 1, 2, 3 and 4, respectively. The declines
in digestibility with the first, second and third feces recyclings (phases
2, 3, 4) were less pronounced than in Trial 1 and smaller than expected.
Organic Matter
The organic matter digestibility means (Table 15) of the four treat-
metns within each phase followed a pattern similar to DM, being 85.8, 83.8,
80.3 and 81.8% in phases 1, 2, 3 and 4, respectively. There were no signi-
ficant differences across phases within treatment. Within a phase, T4 was
generally lower (P<.05) than Tl, T2 and T3, with little difference among
T1+T3.
33
-------
TABLE 15. APPARENT DIGESTIBILITIES OF DRY MATTER, ORGANIC MATTER
ASH AND CRUDE PROTEIN IN TRIAL 2 RATIONS
Rations
Phase 1
2
3
4
SEMJ
Phase 1
2
3
4
SEM
Phase 1
2
3
4
SEM
Phase 1
2
3
4
SEM
Tl
0
84.91'2
85. 2a
79. 8a
81.2a'C
1.3, 1.6
86.0
86. 7a
81. 7a
82.8a'C
1.1, 1.3
59.1
55.4
43. 9a
58.0
4.7, 5.7
74.0
71.4a
65. 4a
67.0
2.2, 2.7
T2
7
86.5
83. 9a
80. 7a
82. 2a
1.4, 1.7
87.8
85. 3a
82. 4a
83. 8a
1.3, 1.6
56.9
59.2,
54.?
59.9
4.2, 5.1
75.8
70. 8a
66. 2a
69.9
1.9, 2.4
T3
14
%_
Dry Matter
85.5
82. 4a
79. if
79.7b'C
1.8, 2.1 2
Organic Matt
86.3
83. 6a
80. 7a
81.2b'C
1.7, 2.0 2
Ash
66.7
58.0,
53.9b
57.0
3.2, 3.9 4
Crude Prote
74.4
69. 8a
63. 5a
66.2
2.5, 3.0 3
T4
21
82. 1-
78.5b
75. Ob
78.0b
.2, 2.8
er
83.0,
79. 6b
76. 4b
79. 5b
.1, 2.6
61.9
57.6
60. 8D
56.6
.6, 5.7
in
70.1,
63. 3b
57. 6b
65.3
.2, 4.0
Means
84.8
82.5
78.6
80.3
85.8
83.8
80.3
81.8
61.2
57.6
53.2
57.9
73.6
68.8
63.2
67.1
SEM
1.2
0.9
0.9
0.7
1.2
1.0
0.9
0.8
2.3
1.9
2.6
1.0
1.6
1.4
1.6
1.1
labc: Values within phase with different superscripts differ significantly
(P<.05).
f\
Values represent the mean of six steers in phases 1, 3 and 4 and four
steers in phase 2.
3 The first number is the standard error of treatment mean (SEM) for phases
1, 3 and 4 of each treatment and the second number is the SEM for phase 2
of each treatment.
34
-------
Ash
Ash digestibility ranged from 56.9 to 66.7% (P>.05) in phase 1 and from
43.9 to 60.8 in phases 2, 3 and 4. In general, the lowered ash digestibility
during recycling can be attributed to the increased ash intake via the feces.
In phase 3, Tl had the lowest (P<.05) ash digestion coefficient. Ration ash
digestibilities were similar (P>.05) in phase 4. There were no significant
differences (P>.05) among phases 1 to 4 within any of the treatments in ash
digestibility.
Crude Protein
Digestion coefficients for crude protein were very similar among Tl,
T2 and T3 in all four phases, but T4 was always lowest (P<.05 in phases 2
and 3). Protein digestibility, averaged across all treatments, was 73.6,
68.8, 63.2 and 67.1% in phases 1, 2, 3 and 4. The largest decline was ap-
parent the first time feces were incorporated, but changed much less there-
after. In general, the protein digestibility followed the pattern observed
for dry matter and organic matter; however, the depression in digestibility
was greater for protein when feces were recycled.
Acid Detergent Fiber
Tl had the lowest acid detergent fiber (ADF) digestibility within all
four phases, being significantly lower (P<.05) than the other rations in
phases 2, 3 and 4 (Table 16). Generally, the highest values were obtained
on T4 (21% CSH). This is in contrast to the other parameters discussed thus
far. The mean ADF digestion coefficients for phases 1 thru 4 were 47.4,
47.3, 41.9 and 52.3%, respectively, reflecting little or no change (in con-
trast to decreases for other parameters cited previously). This implies
that some cellulose and/or lignin in feces is further digested when recycled.
Lignin
In phase 1, lignin digestibility (Table 16) increased as the percent
roughage increased (8.0, 25.4, 26.1 and 28.3%). Correspondingly, lignin
digestibilities were generally higher (P>.05) when feces were included in
the ration for recycling. Within each treatment, lignin digestion coef-
ficients were higher for the feces containing rations than for the basal
ration. The treatment averages (T1-T4) for lignin digestibility in phases
1, 2, 3 and 4 were 22.0, 40.1, 30.3 and 38.2%. Normally, lignin is regarded
as having an extremely low digestibility (perhaps 0-25%). Lignin digesti-
bilities in the 30-40% area would be considerably above usual reported
values and perhaps suggest more extended microbial degradation of lignin
when it is recycled through a ruminant one or more times. In general, cel-
lulose (the largest component of ADF) digestion followed the pattern re-
ported for ADF. While a few significant differences existed among treat-
ments in phases 3 and 4, generally there was little change in cellulose di-
gestibility across phases when feces were reincorporated into the ration
(60.9, 52.9, 52.2 and 59.4% in phases 1, 2, 3, 4, respectively). Again this
suggests some further digestion cf previously indigested cellulose when it
is recycled. The percent of cellulose in the diet or total grams of cel-
lulose presented to the animal when feces are included would be considerably
greater than in the basal ration; hence, if the digestibility (%) is the
same for feces rations, previously indigested cellulose appearing in the
feces would be partially, further digested the first, second or third time
35
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TABLE 16. APPARENT DIGESTIBILITIES OF ACID DETERGENT FIBER, LIGNIN,
CELLULOSE AND NEUTRAL DETERGENT FIBER IN TRIAL 2 RATIONS
Rations
Tl
0
T2
7
T3
14
T4
21
Means SEM
Acid Detergent Fiber
Phase 1 41.01'2 50.3 48.6, 49.6, 47.4 4.5
2 42.2a 48.7? 49.1? 49.2? 47.3 1.6
3 28.3a 45.8? 47.1? 46.4° 41.9 1.9
4 42.2a 54.2b 55.4b 57.5b 52.3 1.3
SEM3 4.6, 5.6 5.2, 6.3 4.3, 5.2 4.9, 6.0
Lignin
Phase 1 8.0 25.4 26.1 28.3, 22.0 7.1
2 32.7a 38.2 38.8a 50.8° 40.1 2.8
3 22.5a 32.6b 41.0° , 25.2? 30.3 1.6
4 33.6a 45.7C 35.7a'D 38.0° 38.2 1.4
SEM 6.7, 8.2 7.7, 9.4 5.5, 6.8 5.2, 6.3
Cellulose
Phase 1 56.3 64.4 61.2 61.8 60.9 3.5
2 57.7 60.0, 58.6, 55.2 57.9 1.4
3 42.la 58.2? 54.7? 53.9b 32.2 1.8
4 48.9a 59.7b 63.1 'c 65.8C 59.4 1.1
SEM 4.0, 4.9 3.7, 4.5 3.6, 4.4 4.1, 5.0
Neutral Detergent Fiber
Phase
1
2
3
4
SEM
77.
77.
65.
69.
1.9,
gr
5a'r
9s
8s
2.3
78.
75.
70.
73.
2.3,
7
4a
1
3
2.8
76.
72.
68.
70.
2.4,
o
7b
4
8
2.9
72.
68.
63.
70.
3.1,
1
9
9
1
3.8
76.1
73.6
67.1
71.0
2.0
1.4
1.7
1.4
labc! Values within phase with different superscripts differ significantly
(P<.05). rs* Values within treatment with different superscripts differ
significantly (P<.05).
Values represent the mean of six steers in phases 1, 3 and 4 and four
steers in phase 2.
3 See Table 15. .»...
36
-------
since cellulose in feces are recycled.
Neutral Detergent Fiber
When feces were included in the ration (phase 2) ...neutral detergent
fiber (NDF) digestibility (Table 16) remained unchanged for Tl but decreased
(P>.05) by approximately 4% for T2, T3 and T4. SligK^'^additional decreases
were observed in most cases during phases 3 (second recycling) and 4 (third
recycling). The treatment means during phases 1, 2, 3 and 4 were 76.1,
73.6, 67.1 and 71.0%. In general, the NDF digestibility values were quite
high in all cases.
The overall digestibility of the rations (T1-VT4) cited in Tables 15 and
16 decreased from phase 1 (no feces) to phase 2 (first recycling) and phase
3 (second recycling) as expected. For unknown reasons, however, the values
in phase 4 (third recycling) were slightly higher than in phase 3. More-
over, the decrease in ration digestibility from one phase to the next was
smaller than expected (implying a higher digestibility of the feces compo-
nent) and less than observed in Trial 1. Ferrell and Garrett (1973) re-
ported a similar trend in ration dry matter digestibility when feces were
refed three consecutive times at a 50% level.
Apparent Digestibility of Fecal Nutrients
The apparent digestibility of nutrients in feces, calculated by dif-
ference, followed the same general pattern as the ration digestion coeffi-
cients in that there was a decrease in the digestibility of fecal nutrients
from phase 2 to 3 (first to second recycling) and an increase in phase 4
(third recycling) as shown in Table 17. The dry matter digestibilities for
feces indicated a dry matter disappearance of 61.3 to 87.0% with the first,
47.6 to 49.6% with the second and 58.6 to 66.3% with the third recycling of
feces. In general, the highest values were observed on Tl (0% CSH), but
the differences were not profound. Organic matter digestibility in feces
was approximately 3 to 4 percentage units higher than the corresponding
fecal dry matter digestibility. This can be attributed to the reduced di-
gestibility noted for the increased ash intake or load when feces were in-
corporated (OM = DM - ash). Digestion coefficients for fecal crude protein,
after one recycling, were 65.4, 51.9, 40.4 and 40.2%, respectively, for the
0, 7, 14 and 21% CSH rations. During the second recycling of feces (phase
3) protein digestibility in the feces was only about one-half (20.0-29.3%)
of that in the first recycling. During the third recycling, values were
similar (42.3-56.1%) to those in the first. Fiber components (ADF, lignin,
cellulose and NDF) were generally high and quite variable. The overall
fecal digestibility means (combining all treatments in recycling phases
2, 3 and 4) for various nutrient parameters in feces are summarized in
Table 18. It is apparent that the nutrient digestion coefficients for the
various fecal parameters are much higher than observed in Trial 1. The
corresponding fecal digestion values in Trial 1 were: PM, 27.0; O.M., 39.0;
Ash, 0.7; crude protein, -3.2; ADF, -14.7%. The reason,? for the higher
fecal digestibilities are not readily apparent, but it> sliould be noted that
the calculation of fecal digestibilities by difference is a highly lever-
aged calculation, particularly when only 15-20% feces are incorporated into
a ration. The average DM digestibility of the 10% CSH basal ration (0%
37
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TABLE 17. DIGESTIBILITY OF FECES AS CALCULATED BY DIFFERENCE FOR TRIAL 2
Rations
Apparent digestibility,
Dry matter
Phase 2
3
4
Mean
Phase 2
Organic matter 3
Ash
4
Mean
Phase 2
3
4
Mean
Phase 2
Crude protein 3
ADF
Lignin
Cellulose
NDF
4
Mean
Phase 2
3
4
Mean
Phase 2
3
4
Mean
Phase 2
3
4
Mean
Phase 2
3
4
Mean
Tl
0
.1
A
87.0
49.6
65.6
91.1
56.8
69.2
33.6
-45.6
53.1
65.4
25.2
49.8
49.3
-46.6
47.5
129.3
60.7
108.0
65.6
41.9
17.6
76.7
-3.3
36.4
T2
7
67.9
49.2
64.9
69.9
53.0
67.7
73.7
39.3
72.1
51.9
29.3
55.6
38.8
21.8
69.7
106.9
62.6
120.2
32.7
24.6
41.1
54.8
23.6
51.6
T3
14
63.4
47.6
58.6
67.2
53.0
62.5
4.9
-8.5
22.0
40.4
20.0
42.3
52.3
40.0
79.8
117.1
113.8
70.2
42.9
22.9
70.1
52.2
31.5
52.1
T4
21
61.3
48.5
66.3
63.2
51.3
69.5
36.8
56.8
41.4
40.2
24.1
56.1
47.2
34.2
79.9
158.2
13.6
65.6
24.0
24.1
77.1
53.4
33.1
64.4
Mean
69.9
48.7
63.8
60.8
72.8
53.5
67.2
64.5
37.2
10.5
47.2
31.6
49.5
24.6
51.0
41.7
46.9
12.4
69.2
42.8
127.9
62.7
91.0
93.9
41.3
28.4
51.5
40.4
59.3
21.2
51.1
43.9
Calculated by difference as outlined by Crampton and Harris (1969).
38
-------
feces in phase 1) in Trial 1 was 85.6% as compared to a mean DM digestibility
of 84.8% for the four basal rations (0, 7, 14, 21% CSH) in phase 1 of Trial 2.
TABLE 18. DIGESTIBILITY OF FECES COMPONENT WHEN RECYCLED
Ration Digestibility Ration Digstibility Digestibility of Feces
Item in Phase 1 in Phases 2, 3, 4 (by difference)
X(T1-T4) X(T1-T4) X
D.M.
O.M.
Ash
C.P-
ADF
84.8
85.8
61.2
73.6
47.4
80.5
82.0
56.2
66.3
47.2
60.8
64.5
31.6
41.7
42.8
Thus, the basal ration (0% feces) digestibilities were very similar in both
trials. In Trial 1, the mean ration DM digestibility in phases 2, 3 and 4
was 76.6 vs. 80.5% in Trial 2. Hence, even a small increase in total ration
digestibility (as noted in Trial 2) can have a rather large increase on the
calculated fecal digestibility when modest levels of feces are involved.
The method for calculating fecal digestibility by difference in Trial 1 can
be illustrated as follows:
Dig. of basal in phase 1 = 85.6%
Dig. of feces ration in phases 2,3,4 = 76.6%
85% of Dig. in phase 1 (85.6 X 85%) =72.7
76.6 - 72.7 = -f'ny f = 26'0% D-M' Digestibility
15.0% feces
Hence, to illustrate the leverage factor, had the mean digestibility in
phases 2, 3 and 4 of Trial 1 been 80.5 instead of 76.6 (a difference of only
3.9%), the calculated fecal DM digestibility would have doubled (e.g.
7.8/15.0 = 52.0%).
Johnson (1972) reported the average calculated theoretical dry matter,
organic matter and crude protein digestibility of feedlot feces to be from
40-50%, 42-56% and 60-71%, respectively, with one recycling of feces at a
25 and 40% level. Fecal dry matter, organic matter, protein and NDF digest-
ibility values were observed by Albin and Sherrod (1975) to be much lower
than those in this trial when feces were refed once at a 20% level. In gen-
eral, the digestibility values for the nutrients in the feces produced by
Trial 2 tended to be high and, particularly so, for the fibrous components
of feces—ADF, lignin, cellulose and NDF.
39
-------
Composition of Feces
The dry matter content of feces, averaged across treatment, increased
from phase 1 to 4 as follows: 24.1, 25.7, 26.4 and 26.9% (Table 19). Per-
cent ash in feces increased more during recycling, being 10.8% ash in phase
1 (no feces in ration) vs_ 13.8 and 13.7% in phases 3 arid 4. Protein and
fiber components (ADF, lignin, cellulose and NDF) also showed a small, but
consistent increase on the order of 2-4%. All fiber components showed a
substantial increase in the feces as the roughage level was increased from
Tl to T4. This was true in all phases. Again it must be recalled that
total residue excretions are a function of the quantity of feces X its com-
position.
The sodium and phosphorus content in feces tended to decrease slightly
with each successive phase (1 to 4) while chlorine and calcium tended to
remain stable. The percent of each fecal nutrient (except minerals) in
Trial 2 was higher within each treatment in phases 2, 3 and 4 than in phase
1. The chemical composition of the feces (excluded minerals) in Trial 2
agrees closely with those previously reported by Anthony (1969, 1971),
Johnson (1972), Lucas £t al (1975) and Tinnimit et^al (1972) and those re-
ported in Trial 1.
Ferrell and Garrett (1973) reported similar trends for calcium, phos-
phorus and sodium concentrations in feces when feces were recycled three
times. They observed calcium to make up approximately 2.5% of the feces;
in this trial the Ca level ranged from 3.18 to 6.15%. Their phosphorus
and sodium contents in feces were similar to those reported in Trial 2 with
phosphorus being approximately 0.7 to 1.0% and sodium being approximately
0.5%.
TABLE 19. COMPOSITION OF FECES IN TRIAL 2
Rations
Tl
0
T2
7
T3
14
T4
21
Means
1 2
Dry matter '
Ash
Crude protein
Phase 1
2
3
4
Phase 1
2
3
4
Phase 1
2
3
4
26.2
26.2
26.2
26.7
10.8
14.6
14.4
13.7
22.2
26.3
24.5
26.0
24.2
26.0
25.8
26.6
13.4
13.5
14.1
14.9
23.2
25.0
24.4
24.6
/o
22.6
24.7
27.2
28.1
9.7
11.6
13.3
13.2
22.1
22.9
23.4
23.3
23.4
26.0
26.2
26.3
9.5
10.0
13.3
13.1
20.3
22.6
22.3
22.8
24.1
25.7
26.4
26.9
10.8
12.4
13.8
13.7
22.0
24.2
23.6
24.2
40
-------
TABLE 19. CONT'D. COMPOSITION OF FECES IN TRIAL 2
ADF
Lignin
Cellulose
NDF
Sodium
Chlorine
Calcium
Phosphorus
Rations
Phase 1
2
3
4
Phase 1
2
3
4
Phase 1
2
3
4
Phase 1
2
3
4
Phase 1
2
3
4
Phase 1
2
3
4
Phase 1
2
3
4
Phase 1
2
3
4
Tl
0
17.6
22.0
25.8
28.4
7.0
9.1
9.7
12.0
10.7
12.4
14.6
15.9
36.4
40.7
46.2
46.7
0.42
0.57
0.47
0.40
0.22
0.23
0.34
0.24
4.26
6.15
5.19
4.83
1.05
1.35
0.88
0.78
T2
7
31.0
36.1
35.8
35.6
12.0
14.7
15.6
14.3
18.3
20.6
19.1
20.4
45.8
48.8
50.3
49.3
0.60
0.53
0.64
0.48
0.22
0.22
0.25
0.28
5.56
5.28
5.11
4.42
1.25
1.02
0.84
0.71
T3
14
43.3
45.5
44.4
43.9
16.4
16.8
16.3
20.3
26.5
28.1
26.5
25.4
55.1
55.2
55.6
55.4
0.65
0.50
0.43
0.38
0.28
0.34
0.31
0.25
3.18
3.77
4.72
4.46
0.84
0.61
0.64
0.60
T4
21
45.4
49.5
49.8
47.7
17.1
16.5
19.7
22.5
27.8
32.5
27.4
26.5
57.4
59.0
62.0
59.2
0.58
0.46
0.56
0.47
0.30
0.34
0.32
0.29
3.61
3.22
4.05
3.97
0.71
0.54
0.57
0.87
Means
34.3
38.3
39.0
38.9
13.1
14.3
15.3
17.3
20.8
23.4
21.9
22.0
48.7
50.9
53.5
52.6
0.56
0.52
0.52
0.43
0.26
0.28
0.30
0.26
4.15
4.60
4.77
4.42
0.96
0.88
0.73
0.74
Values represent the mean of six observations per treatment in phases 1,
3 and 4 and four observations per treatment in phase 2.
All nutrients, except dry matter, are on a 100% dry basis.
41
-------
Composition of Urine
The percent crude protein in urine (Table 20), averaged within phase,
increased almost two-fold in phases 2, 3 and 4 compared to phase 1 (1.90,
3.79, 4.61, 4.69%). Sodium and chlorine content in urine was also higher
within each treatment when feces were included in the rations (phases 2, 3
and 4). The percent phosphorus in urine followed a similar pattern.
TABLE 20. COMPOSITION OF URINE IN TRIAL 2
Rations
Tl
0
T2
7
T3
14
T4
21
Means
Crude protein
Sodium
Chlorine
Phosphorus
Phase 1
2
3
4
Phase 1
2
3
4
Phase 1
2
3
4
Phase 1
2
3
4
2.33
3.25
5.24
5.08
0.08
0.09
0.18
0.20
0.14
0.17
0.28
0.29
0.10
0.07
0.18
0.19
2.08
4.68
5.56
3.82
0.08
0.14
0.17
0.16
0.15
0.20
0.30
0.23
0.06
0.14
0.14
0.13
1.45
3.80
4.46
4.74
0.04
0.09
0.15
0.18
0.10
0.16
0.24
0.25
0.05
0.14
0.17
0.22
1.75
3.43
3.19
5.13
0.04
0.09
0.09
0.16
0.10
0.15
0.16
0.24
0.06
0.12
0.14
0.21
1.90
3.79
4.61
4.69
0.06
0.10
0.15
0.18
0.12
0.17
0.24
0.25
0.07
0.12
0.16
0.19
Values represent the mean of six observations per treatment in phases 1,
3 and 4 and four observations per treatment in phase 2.
Residue Accumulations
Indigestible dry matter excretions (Table 21) on the 0, 7, 14 and 21%
basal rations were 600.0, 535.8, 577.5 and 713.9 g per day, respectively,
as compared to 590.1, 640.9, 702.4 and 860.4 in phase 2 (first recycling).
The nearly identical excretions in phase 1 and 2 on the 0% CSH diets sug-
gest that feces served as an effective roughage replacement and produced
positive associative effects on digestibility. On an average, phase 2 pro-
duced about a 15% increase in total residues over phase 1. In phase 3 the
average residue excretion was approximately 21% higher than in phase 2.
Phase 4 showed no further increase. In all cases, the most profound dif-
ferences were observed on T4, which can be accounted for by the high rough-
age level.
42
-------
Phase averages for indigestible ash residues were 64.4, 84.8, 117.2 and
109*8 g per day for phases 1 thru 4, respectively. No consistent trends
were observed among treatments within a phase in ash accumulations. This
is logical in that total ash content of the rations within a phase differed
little.
TABLE 21. INDIGESTIBLE NUTRIENTS EXCRETED IN FECES IN TRIAL 2
Rat:
Dry matter
Ash
ADF
Lignin
Cellulose
NDF
Lons
Phase 1
2
3
4
Phase 1
2
3
4
Phase 1
2
3
4
Phase 1
2
3
4
Phase 1
2
3
4
Phase 1
2
3
4
Tl
0
600.0
590.1
806.7
760.8
64.5
86.0
116.0
104.3
105.8
129.6
206.5
215.1
42.4
53.4
77.6
91.0
64.0
72.7
117.0
120.5
218.2
240.5
373.1
355.1
T2
7
535.8
640.9
771.5
723.3
70.3
86.0
107.6
107.6
164.5
229.4
277.6
256.5
64.1
93.2
120.6
103.0
96.2
131.4
148.2
147.2
243.7
311.5
388.8
357.4
T3
14
577.5
702.4
836.7
828.5
56.2
81.3
110.9
108.4
248.3
318.5
370.0
361.0
93.0
117.7
135.7
166.0
152.8
196.5
221.2
208.4
314.8
387.0
465.6
458.8
T4
21
713.9
860.4
1002.4
902.5
66.4
85.9
134.1
119.0
320.2
425.1
498.7
429.5
119.2
141.3
195.4
202.2
197.8
279.9
272.4
238.0
412.2
507.0
618.9
532.5
Means
606.8
698.4
854.3
803.8
64.4
84.8
117.2
109.8
209.7
275.6
338.2
315.5
79.7
101.4
132.3
140.6
127.7
170.1
189.7
178.5
297.2
361.5
461.6
426.0
Values represent the mean of six observations per treatment in phases 1,
3 and 4 and four observations per treatment in phase 2.
ADF, lignin, cellulose and NDF residues, expressed as grams per day,
increased within each phase as the percent of roughage increased in the
43
-------
rations. This trend was expected since these are the major constituents of
roughage. Moreover,' indigestible fiber components showed a sizeable increase
in the first recycling with some additional increase in phases 3 and 4.
Crude protein and minerals are excreted in both the feces and urine
(Table 22). Total indigestible crude protein in the feces (grams per day)
increased by 5.4% with one recycling (phase 1 to 2) for Tl and 12-20% for
T2, T3 and T4. The second recycling of feces (phase 3) resulted in total
indigestible protein residue increases of 18.0 (Tl), 11.5 (T2), 2.9 (T3)
and 2.0% (T4) over the first recycling (phase 2). Values in the third re-
cycling (phase 4) were similar to those in the second.
Daily sodium (Na) excretion, averaged across phase, was very similar
for all four phases (8.8 to 10.5 g). Except for Tl, total grams of chlorine
(Cl) excreted daily (as in Trial 1) were less for steers fed the feces
rations (phases 2, 3, 4) than for those fed the basal ration (phase 1).
This was likely due to the fact that most chlorine is excreted in the urine,
and not feces. Moreover, feces replaced a portion of the basal ration and
feces are low in Cl. Calcium (Ca) was analyzed only in the feces in Trail 2
as Ca levels in the.urine are so low that accurate determinations are dif-
ficult to make. T£tal grams of Ca excreted daily increased with the first
and second recyclin'g" of feces (phase 2 and 3), but showed no further in-
crease with the third recycling (phase 4). Total phosphorus (P) excretion
averages for phases 1 to 4 were 12.3, 11.7, 12.9, and 13.2 g per day, res-
pectively. As in Trial 1, phosphorus excretion occurred about equally be-
tween feces and urine; whereas, Na and Cl were excreted to a greater degree
in the urine. Except for Ca, recycling as conducted in this study, pro-
duced no buildups in mineral residues. Had the urine been refed, the answer
may have been different! However, this could be corrected by altering
mineral formulation in the diet. Of all the nutrients, Na, Cl and P showed
the least tendency to accumulate when recycling feces three consecutive
times. However, if feces were recycled ten consecutive times with the rough-
age levels spaced out more, overall trends in residue accumulations could
be much better established.
Mineral Retention
Grams of sodium (Table 23), chlorine (Table 24), calcium (Table 25) and
phosphorus (Table 26) retained per day tended to increase with the first
recycling (phase 2%, decrease with the second recycling (phase 3) and in-
crease again with the third recycling of feces (phase 4). However, the dif-
ferences were not Igraat. The high retention values for calcium in phase 4
were surprising eternally since there were negative or small retention
values in the othejj^fcee phases. The average daily retentions of sodium,
chlorine, calcium|HB|Ksphorus were 5.87, 4.84, 4.22 and 7.06 g, respect-
ively. These re«BE3Palues represented approximately 38.1% of the min-
eral intake for saBflpI, 28.8% for chlorine, 11.4% for calcium and 36.0% for
phosphorus. These values are somewhat higher than in Trial 1.
General Conclusions in Recycling Trials 1 and 2.
1. Total ration nutrient digestibility decreased when feces were refed
44
-------
TABLE 22. RESIDUES WHICH ACCUMULATED IN FECES AND URINE ON TRIAL 2
in
Tl
Rations 0
Phase 1
2
3
4
Phase 1
2
3
4
Phase 1
2
3
4
Phase 1
2
3
4
Phase 1
2
3
4
Feces Urine
123.6 199.6
139.3 201.4
179.4 222.6
173.6 198.2
2.5 7.0
3.3 5.7
3.8 7.6
3.2 7.8
1.3 11.7
1.4 10.9
2.7 11.4
1.8 11.6
25.6
36.0
41.&^^- —
37j*|j» jMjjW
6?$!ljjjj$.\
8.3 4.8
7.3 8.1
6.0 7.8
Total
323.2
340.7
402.0
371.8
9.5
9.0
11.4
11.0
13.0
12.3
14.1
13.4
25.6
36.0
41.6
^37. 1
' 14.6
13.1
15.4
13.8
Feces
118.1
147.0
172.0
164.5
3.3
3.5
4.9
3.5
1.2
1.4
1.9
2.0
29.1
33.5
39.2
31.9
1 7.2
6.5
6.4
5.2
T2
7
Urine Total
180.3 298.4
202.6 349.6
217.9 389.9
168.0 332.5
7.3 10.6
5.9 9.4
6.6 11.5
6.2 9.7
14.0 15.2
8.5 9.9
12.8 14.7
9.5 11.5
29.1
33.5
39.2
31.9
6.1 13.3
6.4 12.9
5.8 12.2
6.7 11.9
T3
14
Feces Urine Total
g/day
Crude Protein1
118.9 149.7 268.6
155.8 167.8 323.6
180.6 152.3 332.9
179.6 171.3 350.9
Sodium
3.9 3.9 7.8
3.5 3.9 7.4
3.7 5.5 9.2
3.2 6.2 9.4
Chlorine
1.6 10.5 12.1
2.4 7.2 9.6
2.6 8.5 11.1
2.1 8.7 10.8
Calcium
18.4 18.4
26 . 1 26 . 1
39.5 39.5
37.1 37.1
Phosphorus
4.8 5.1 9.9
4.3 5.9 10.2
5.4 6.1 11.5
5.0 8.2 13.2
Feces
136.7
179.4
201.6
192.6
4.3
3.9
5.5
4.3
2.1
2.9
3.1
2.6
24.9
27.8
40.2
36.2
5.1
4.6
5.7
7.9
T4
21
Urine
169.8
165.1
149.8
150.9
4.1
5.1
4.5
4.9
10.4
7.7
7.9
7.3
6.4
6.3
6.7
6.0
Means
Total
306.5
344.5
351.4
343.5
8.4
9.0
10.0
9.2
12.5
10.6
11.0
9.9
24.9
27.8
40.2
36.2
11.5
10.9
12.4
13.9
Feces
124.3
155.4
183.4
177.6
3.5
3.6
4.5
3.6
1.6
2.0
2.6
2.1
24.5
30.8
40.1
35.6
5.9
5.9
6.2
6.0
Urine
174.8
184.2
185.6
172.1
5.6
5.2
6.0
6.3
11.6
8.6
10.2
9.3
6.4
5.8
6.7
7.2
Total
299.1
339.6
369.0
349.7
9.1
8.8
10.5
9.9
13.2
10.6
12.8
11.4
24.5
30.8
40.1
. 35.6
12.3
11.7
12.9
13.2
1
Values represent the mean of six observations per treatment for phases 1, 3 and 4. Phase 2 had four
observations per treatment.
-------
in the ration, but decreases were less than expected.
2. In general, feces appeared to have a low to moderate, but rather
variable digestibility when refed. Average calculated digestibi-
lity values for different nutrient parameters in recycled feces in
Trial 1 were: D.M. 27.0; O.M. 39.0; Ash 0.7; C.P. -3.2; ADF -14.7%.
The values were higher in Trial 2 being: D.M. 60.8; O.M. 64.5;
Ash 31.6; C.P. 41.7 and ADF, 42.8%.
3. Low levels of roughage appear to produce desirable associative ef-
fects on ration digestibility in high concentrate rations.
4. Feces in 0% roughage rations appear to have roughage value and
produce positive associative effects on ration digestibility.
5. Recycling appears to enhance digestibility of fiber components in
feces; the less digestible components (cellulose, lignin) in feces
tended to increase with each successive recycling.
6. Feces would appear to be a low energy feed which has potential in
maintenance type programs or as a source of fiber in 0% roughage
rations.
7. Indigestible residues accumulated in feces during recycling, but
not at the rate expected. Moreover, the change from phase to phase
was smaller and more erratic than anticipated.
8. Fecal composition was altered during recycling; dry matter content
increased several percent, and on a dry matter basis, the feces be-
came higher in C.P., ash and fiber, particularly during the first
recycling. Less change occurred thereafter during the second and
third recyclings.
9. Feces can be recycled three times without any material buildups of
Na, Cl or P. Ca, however, showed a definite accumulation. Re-
feeding both feces and urine might have altered observations on
Na, Cl and/or P.
10. Recycling produced normal mineral retention values.
Recommendations for Improval of Trial Design
Based upon the evidence obtained in these studies modifications in
trial design might have been helpful to provide more definitive data.
1. More phases (recyclings). If feces were refed more consecutive
times (e.g. 8-10), a more meaningful relationship could have been established
between number of recyclings and ration digestibilities, nutrient digesti-
bility in feces, residue accumulations, composition of feces and urine,
mineral retention and overall acceptance by the animals to feces in the diet
when fed over prolonged periods of time. This would have permitted regres-
sion and correlation analyses of the data to be conducted in a meaningful way.
46
-------
TABLE 23. SODIUM RETENTION IN TRIAL 2
Rations
Tl
0
T2
7
T3
14
T4
21
Means
SEM
Phase
Phase
Phase
Phase
Intake
1 Fecal excretion
Urine excretion
Net retention
Intake
2 Fecal excretion
Urine excretion
Net retention
Intake
3 Fecal excretion
Urine excretion
Net retention
Intake
4 Fecal excretion
Urine excretion
Net retention
SEM3
14.98
2.50
6.98 ,
5.50a'b
14.47
3.34
5.73
5.40a
14.91
3.81
7.58
3.52a
15.24
3.20
7.80
4.24a
1.6, 2.0
15.02
3.32
7.30
4.40a
15.29
3.46
5.93
5.90a
15.13
4.88
6.61
3.64a
19.14
3.48
6.22,
9.44b
1.6, 1.9
g/ aa
15.07
3.91
3.87,
7.29b
16,73
3.50
3.94
9.29b>°
15.25
3.74
5.51,
6.00b'C
13.67
3.18
6.17
4.32a'c
1.0, 1.2
y
15.12
4.30
4.07,
6.75b
15.95
3.93
5.07
6.95a>
15.33
5.50
4.54
5.29a'
15.17
4.29
4.87
6.01°
1.2, 1.
15.05
3.51
5.56
5.98
15.61
3.56
5.17
°6.88
15.16
4.48
6.06
C4.61
15.80
3.54
6.26
6.00
4
0.7
0.8
0.6
0.6
Values within phase (across treatments) with different superscripts
differ significantly (P<.05).
2
Values represent the mean of six observations per treatment in phases 1,
3 and 4 and four observations per treatment in phase 2.
3 See Table 15.
2. Wider spread of roughage levels. Since ration digestibilities did
not decrease significantly as level of roughage increased (due to the levels
being spaced too closely), regression lines and correlations would have been
meaningless. Ration digestibilities would have shown more decrease if the
roughage levels were spread out more (e.g. 0, 14, 28, 42%, etc.), thereby
allowing extrapolation by regression for residue accumulations, etc. in
feces and urine when feces are being recycled over a broader range of rations,
Different kinds of roughages or diets may also give different results. The
digestibility of feces may also be a function of the amount in the diet and
the nature of other dietary ingredients.
3. Change of experimental design. The length of time required to com-
plete the animal collection portion of Trial 2 was tremendous—approximately
8 months. Therefore, time could have influenced or confounded the results
47
-------
TABLE 24. CHLORINE RETENTION IN TRIAL 2
Phase
Phase
Phase
Phase
Rations
Intake
1 Fecal excretion
Urine excretion
Net retention^-
Intake
2 Fecal excretion
Urine excretion
Net retention
Intake
3 Fecal excretion
Urine excretion
Net retention
Intake
4 Fecal excretion
Urine excretion
Net retention
SEM3
Tl
0
18.06
1.31
11.66
5.09
16.66
1.38
10.92
4.36
16.39
2.74
11.37
2.28
15.90
1.84
11.64
2.42a
1.6, 2.0
T2
7
18.08
1.19
13.98
2.91
16.59
1.44
8.47
6.68
16.30
1.89
12.80
1.61
16.04
2.04
9.50 .
4.50a'b
1.5, 1.8
T3
14
—nlA
g/Q
18.10
1.60
10.48
6.02
16.78
2.45
7.24
7.09
16.67
2.61
8.50
5.56
16.16
2.09
8.72
5.35b
1.2, 1.
T4
21 1
av2 __
ay
18.12
2.06
10.39
5: 67
16.50
2.86
7.71
5.93
16.20
3.12
7.93
5.15
16.69
2.65
7.30
»c 6.74°
5 1.2, 1
yfeans
18.09
1.54
11.63
4.92
16.63
2.03
8.58
6.02
16.39
2.59
10.15
3.65
16.20
2.16
9.29
4.75
.5
SEM
0.9
0.9
1.2
0.7
labc:
Values within phase (across treatments) with different superscripts
differ significantly (P<.05).
2
Values represent the mean of six observations per treatment in phases 1,
3 and 4 and four observations per treatment in phase 2.
3
See Table 15.
to some degree since the basal ration digestibilities (baseline or bench
mark values) were determined at the beginning. An alternative experimental
design might be to collect enough feces for each treatment in phase 1 such
that ample feces could be stored for refeeding in a separate digestion study
to be conducted at a later date to determine residue accumulation with one
recycling and still have feces left from phase 1 to refeed in phase 2.
Likewise, a portion of the feces produced at the end of phase 2 could be
stored for refeeding at a later date to determine residue accumulation with
two recyclings and part could be used for refeeding in phase 3. Similarly,
a portion of the feces produced in phase 3 could be saved for refeeding in
a later digestion trial, etc. while the remainder is fed in phase 4. this
procedure could be followed for the number of cycles desired. If there
were 4 treatments/phase and 3 recycling phases, at this point, there would
be 16 rations to compare (4 basal, 12 feces containing ones). The stored
48
-------
TABLE 25. CALCIUM RETENTION IN TRIAL 2
Phase
Phase
Phase
Phase
Rations
Intake
1 Fecal excretion
Net retention
Intake
2 Fecal excretion
Net retention
Intake
3 Fecal excretion
Net retention
Intake
4 Fecal excretion
Net retention
SEM4
Tl
0
21.85
25.56
-3.71a
35.68
36.03
-0.35
41.58
41.58
0.00
52.04
37.12
14.92
4.9, 6.0
T2
7
22.11
29.11
-7.00a>
38.07
33.51
4.56r
40.89
39.20
1.69r
54.22
31.90
22.32s
3.2, 4.0
T3
14
g/day
22.37
18.36.
r 4.01b
33.07
26.10
6.97
38.34
39.49
-1.15
46.59
37.12
9.47
3.1, 3.8
T4
21
2,3
22.64
24.90
-2.26;
35.19
27.76
7.43
36.34
40.16
-3.82
50.66
36.20
14.46
4.6, 5
Means
22.24
24.48
a -2.24
35.50
30.85
4.65
39.29
40.11
-0.82
50.88
35.58
15.29
.6
SEM
1.8
1.8
1.9
3.7
labc!
Values within phase (across treatments) with different superscripts
differ significantly (P<.05). rs: Values within treatment (across phase)
with different superscripts differ significantly (P<.05).
2
Values represent the mean of observations per treatment in phases 1, 3 and
4 and four observations per treatment in phase 2.
3
Calcium was not analyzed in the urine since over 99% of the excretion
is in the feces.
4 See Table 15.
feces from phase 1 would be incorporated into the basal rations based on
the indigestible dry matter production for each treatment in phase 1. Like-
wise, the feces stored from phases 2, 3 etc. could be reincorporated into
the basal rations based on the indigestible dry matter produced during the
appropriate phases. By such an arrangement, all rations could be compared
at once in a randomized block design (blocked on time for replication) with
4-6 replications per treatment. Thus, time would be eliminated as a var-
iable in comparing residue accumulations from recycling feces since all re-
cycling treatments could be represented simultaneously. Another and perhaps
more desirable alternative would be to include feces from each recycling
phase at the same level (e.g. 50%) or two different (e.g. 25 and 50%) levels
in the digestion trial rations. Other design possibilities exist (e.g. 2
basal treatments in phase 1, followed by 8 recyclings of each; or 1 basal
treatment followed by 8 or 10 recyclings; or 4 X 4 or 6 X 6 Latin square
49
-------
possibilities could be used). In any event, a design whereby time could be
removed as a variable would be advantageous. Moreover, conduction of-more
replicates/treatment simultaneously to delete the need for periods or to re-
duce the number of periods within a phase would likely add some precision
to digestibility estimates. Incorporating higher levels of feces in diges-
tion trial studies would also tend to reduce any leverage factor in esti-
mating fecal digestibility parameters.
4. Incorporation of both feces and urine. Protein digestibility and
mineral residue excretion patterns may differ somewhat if both feces and
urine were reincorporated during recycling.
TABLE 26. PHOSPHORUS RETENTION IN TRIAL 2
Phase
Phase
Phase
Phase
Rations
Intake
1 Fecal excretion
Urine excretion
Net retention
Intake
2 Fecal excretion
Urine excretion
Net retention
Intake
3 Fecal excretion
Urine excretion
Net retention
Intake
4 Fecal excretion
Urine excretion
Net retention
Tl
0
19.71
6.49
8.06
5.16
20.71
8.29
4.78
7.64
21.18
7.31
8.08
5.79
20.53
5.99
7.81
6.73a'c
T2
7
18.98
7.20
6.11
5.67
20.53
6.54
6.38
7.61
19.92
6.39
5.83
7.70
21.48
5.19
6.73,
9.56b
T3
14
2
— g/day —
18.25
4.77
5.06
8.42r's
19.94
4.29
5.89
9.76r
18.42
5.42
6.10c
6.90*'*
18.22
4.95
8'22a t
5.05a>t
T4
21
17.52
5.12
6.35
6.05
17.82
4.63
6.31
6.88
18.32
5.69
6.69
5.94
22.00
7.86
5.99,
8.15b
Means
18.62
5.90
6.40
6.32
19.75
5.94
5.84
7.97
19.46
6.20
6.68
6.58
20.56
6.00
.7-19
'C7.37
SEM
1.5
1.0
0.6
0.7
Values within phase (across treatments) with different superscripts
differ significantly (P<.05). rst: Values within treatment (across
phase) with different superscripts differ significantly (P<.05).
n
Values represent the mean of six observations per treatment in phases 1,
3 and 4 and four steer observations per treatment in phase 2.
50
-------
SECTION VII
TRIAL 3--NITROGEN DEPLETION-REPLETION STUDY
SUMMARY
Urine collected from steers in Trials 1 and 2 was evaluated as a sup-
plemental nitrogen (N) source in Trial 3. Iso-nitrogenous rations contain-
ing 0, 1.6, 3.2 or 4.9% dried urine as a replacement for 0, 25, 50 and 75%
of the supplemental N supplied by soybean meal were compared in a N deplet-
ion-repletion study with young, growing lambs. The lambs were placed on a
low N depletion ration for 4 weeks, following by a 5-week repletion period
on the test diets.
Ration dry matter digestibility averaged approximately 6.6% higher
and crude protein digestibility about 8.1% higher on all treatments during
the first 2 weeks of the repletion period than during the last 3 weeks.
This suggests that physiological or nutritional status may influence digest-
ive efficiency. Moreover, greatest N retention efficiency was noted during
the first several weeks following depletion when the lambs still had a
rather depleted N status. During the first week, N retention, expressed
either as % absorbed or % consumed N retained, was higher (P<.05) on the
0, 1.6 and 3.2% urine diets than on the 4.9% urine diet. The same pattern
was noted during the second week. By the fifth week, the lambs had repleted
their N reserves to the point that N response parameters were the same on
all 4 treatments. Treatment differences were most profound during the first
week, decreased thereafter and equalized by the end of the fifth week.
Urinary N appeared to be readily available for utilization and promoted
better N retention efficiencies than anticipated. The average daily pro-
tein retention per kg of metabolic body weight during the entire 5-week
period was 5.2, 5.6, 6.1 and 4.8 g on the 0, 1.6, 3.2 and 4.9% urine diets,
respectively (P<.05).
INTRODUCTION
Urine contains nitrogen (N) and thus should have merit as a supplement-
al N source. A relatively new technique has been developed to evaluate ef-
ficiency of N utilization. First, young lambs are fed a diet which is very
low in N for a period of 3 to 4 weeks to deplete their N reserves. At this
point, the lambs will be in a negative N balance, which means they will be
excreting more N than what they are consuming. The next stage is the reple-
tion phase where the lambs are assigned either to rations which contain gra-
duated levels of the N test source or different nitrogen sources. Efficien-
cy of N utilization is measured by the net amount of N retained.
51
-------
Therefore, the purpose of this trial was to evaluate the efficiency of
N utilization from steer urine by using the N depletion-repletion procedure
with young, growing lambs.
MATERIALS AND METHODS
Experimental Design
Sixteen young (12-week-old), crossbred Western lambs averaging about
20 kg were fed a N-depletion ration for four weeks (Table 27). Then the
lambs were placed in digestion stalls and randomly assigned to one of four
N-repletion rations (Table 28). The N-repletion rations consisted of 20%
dried steer feces, along with 0, 2, 4 or 6% partially dried steer urine (0,
1.6, 3.2 and 4.9% urine on DM basis) which were obtained from Trials 1 and 2.
The composition of the feces and urine is shown in Table 29. The N from
the urine replaced 25, 50 and 75%, respectively, of the total supplemental
N supplied by soybean meal (control). The lambs were fed once daily at a
level equal to 90 g/kg°-75 initial body weight at the beginning of the re-
pletion phase. This represented a rather high level of daily intake (in
excess of 4.0% of body weight). Feed weighbacks were recorded weekly. The
repletion phase was conducted for five weeks. Feces and urine were col-
lected and weighed daily during the repletion phase. The total individual
daily collections were frozen and composited weekly by lamb. Aliquots were
taken for laboratory analyses. The lambs were weighed at the beginning and
end of the trial. Water was available at all times.
TABLE 27. NITROGEN-DEPLETION RATION FED IN TRIAL 3
Ingredient %
Cottonseed hulls, 1-01-599 45.1
Dried molasses, 4-04-695 15.4
Corn starch 9.9
Ground corn, 4-02-935 28.5
Calcium carbonate, 6-02-632 0.4
Dicalcium phosphate, 6-01-080 0.4
Trace mineral salt 0.2
667 I.U. Vitamin A/kg +
67 I.U. Vitamin D/kg +
Dry matter basis.
Laboratory Analyses
Dry Matter
A 300 g sample of wet sheep feces was placed in a 60° forced air oven
for 48 hours. The samples were removed and allowed to equilibrate with air
for 24 hr before weighing. The samples were then ground through a 20 mesh
screen in a small laboratory mill, and dry matters were determined on the
dried feces according to AOAC (1965).
52
-------
TABLE 28. NITROGEN-REPLETION RATIONS FED IN TRIAL 3
Ingredient
Cottonseed hulls, 1-01-599
Dried feces
Dried molasses, 4-04-695
Soybean meal, 5-04-604
Ground corn, 4-02-935
Dried urine^>3
Corn starch
Calcium carbonate, 6-02-632
Dicalcium phosphate, 6-01-080
Trace mineral salt
667 I.U. Vitamin A/kg
67 I.U. Vitamin D/kg
Composition:
Dry matter
Crude protein
Tl
8.9
18.5
13.7
10.7
28.0
8.8
0.4
0.4
0.2
+
+
89.5
14.2
T2
8.9
18.5
13.7
8.0
28.8
1.6
8.8
0.4
0.4
0.2
+
+
89.3
14.1
T3
8.9
18.5
13.7
5.4
29.7
3.2
8.8
0.4
0.4
0.2
+
+
89.1
14.0
T4
8.9
18.5
13.7
2.7
30.6
4.9
8.8
0.4
0.4
0.2
+
+
89.0
13.9
Dry matter basis.
2
Added at levels to keep all treatments iso-nitrogenous.
3
N Composition—Dry matter basis.
total N - 10.17%
soluble N - 9.52%
non-protein N - 7.73%
urea N - 5.16%
TABLE 29. COMPOSITION OF FECES AND URINE USED IN TRIAL 3
REPLETION RATIONS
Item
Dry matter
Ash1
Crude protein .
Acid-detergent fiber
Feces
_ _7
92.4
10.5
18.6
34.0
Urine
81.3
63.6
Dry matter composition.
53
-------
Crude Protein
Kjeldahls were done on the feces and urine samples for N determination
according to AOAC (1965) methods. At first, Kjeldahls were done on both
the wet and dry sheep feces. However, since there was little difference in
the results between the two samples, Kjeldahls were discontinued on the wet
samples. Thus, all the calculations are based on the crude protein values
obtained on the dry feces samples.
Calculations
Digestion coefficients were calculated in the conventional manner.
Nitrogen balance data was calculated on the basis of metabolic weight,
kg0*7*, to minimize any error resulting from differences in lamb size.
Statistical Analyses
Statistical analyses were done by analysis of variance, and differences
among means were tested by least significant differences according to
Snedecor and Cochran (1967).
RESULTS AND DISCUSSION
Week 1.
Dry matter and crude protein intakes (Table 30) were slightly higher
on the 4% urine ration, although the differences were not significant
(P>.05). Dry matter and crude protein digestibilities, crude protein ab-
sorbed and crude protein excreted were similar among treatments. However,
the 4% urine treatment had the most favorable values for all these para-
meters, while the 6% urine treatment had the least favorable. Thus, grains
of protein retained per day, per unit of metabolic weight, were higher
(P<,05) on the 0 and 4% urine rations than on the 6% urine ration (6.7 and
8.0 vs 4.9 g/day, respectively). Lambs on the 2% urine ration retained an
intermediate amount, 6.4 g/day (P>.05). Nitrogen (N) retention, expressed
either as % absorbed or % consumed N retained, was higher (P<.05) for lambs
fed the 0, 2 and 4% urine rations as compared to lambs fed the 6% urine
ration. In general, during the first week of the repletion phase, the
lambs utilized N most efficiently from the 4% urine ration and least effi-
ciently from the 6% urine ration. This might be attributed to the slightly
greater intakes on the 4% treatment.
Week 2.
Although there were no significant (P>.05) differences among the
rations in week 2 (Table 31) for any of the N balance parameters, dry mat-
ter and protein intakes were slightly higher on the 0 and 4% urine rations
as were the grams of absorbed protein. The grams of protein retained daily
were slightly lower in week 2 on the 0, 2 and 4% urine rations, but similar
to week 1 on the 6% urine ration. Lambs fed the 0, 2, 4 and 6% urine
rations retained 5.9, 6.0, 6.6 and 5.0 g per day in week 2 vs 6.7, 6.4, 8.0
and 4.9 g per day in week 1. The percent absorbed and consumed N also de-
creased slightly in week 2, except on the 6% urine treatment. In general,
54
-------
the lambs consuming the 0 and 4% urine rations were still the most effi-
cient, and the lambs consuming the 6% urine ration the least efficient.
But, the differences as illustrated in Figures 2 and 3 were somewhat less.
TABLE 30. N BALANCE FOR WEEK ONE OF TRIAL 3
Item4
Dry matter intake, g/kg * /day *
Dry matter digestibility, %
Crude protein intake, g/kg^'^/day
Crude protein digestibility, %
Crude protein absorbed, g/kg
/day
Tl
86.7
79.8
12.4
73.6
9.1
T2
83.3
82.2
11.8
76.2
9.0
T3
89.1
86.2
12.5
78.7
9.8
T4
83.4
78.2
11.6
65.1
7.6
SEM
2.6
3.8
0.6
Urinary crude protein excreted,
g/fcgU.75;
'day
2
Crude protein retained, g/kg
/day
% Absorbed N
% Consumed N
retained
retained
6
74
54
.3
.7a
t0a,c
.7a
2
6
71
55
.5
.4a>
.9a
.Oa
1.
8.
81.
63.
8
oa
3°
9a
2
4
62
41
.8
v.
.9b
.2b
.lb
0
0
3
4
.2
.5
.0
.2
Standard error of the mean.
9
Values represent the mean of four lambs per treatment.
Values in a row with different superscripts differ significantly
(P<.05).
Tl, T2, T3, T4 represent 0, 2, 4 and 6% urine, respectively.
Week 3.
Although daily dry matter and crude protein intakes in week 3 (Table
32) were identical to week 2 for each corresponding ration, dry matter and
crude protein digestibilities were lower (4-7% and 7-10%, respectively).
As a result, the grams of absorbed protein were also lower in week 3. Since
the grams of protein excreted in the urine were similar for weeks 2 and 3,
net protein retention (grams) in week 3 was 10-20% lower on the 0, 2 and 4%
urine rations and 4% lower on the 6% urine ration. The percent absorbed
and consumed N retained was lower in week 3 than in week 2 for all the
rations except the 6% urine ration. The 4 % urine ration showed the
greatest decrease in both of these parameters, likely due to the higher
55
-------
80
-a 76
| 72
£ 68
-o 64
I 60
.o
1 56
52
48.
0
o 0% Urine
A 2% Urine
• 4% Urine
A 6% Urine
234
Repletion Period, Weeks
FIGURE 2. PERCENT ABSORBED N RETAINED
abc: Points within each week differ significantly
(P<.05).
56
-------
8.0
7.5
-§7.0
10
°o.6.5
o 5.5
^5.0
o
4.5
4.0
3.5
0
o 0% Urine
* 2% Urine
• 4% Urine
6% Urine
1
234
Repletion Period, Weeks
FIGURE 3. GRAMS OF PROTEIN RETAINED
ab: Points with different letters within each week
differ significantly (P<.05).
57
-------
TABLE 31. N BALANCE FOR WEEK TWO FOR TRIAL 3
Item
Dry matter intake, g/kg°'75/day
Dry matter digestibility, %
Crude protein
Crude protein
Crude protein
Urinary crude
/day
Crude protein
% Absorbed N
intake, g/kg°-75/day
digestibility, %
absorbed, g/kg°'75/day
protein excreted, g/kg
retained, g/kg°'75/day
retained
% Consumed N retained
Tl
87.
75.
12.
64.
8.
2.
5.
73.
47.
TABLE 32. N BALANCE FOR WEEK
Item
Dry matter intake, g/kg° /day
Dry matter digestibility, %
Crude protein
Crude protein
Crude protein
Urinary crude
/day
Crude protein
intake, g/kg°'75/day
digestibility, %
absorbed, g/kg * /day
protein excreted, g/kg
, 0-75,
retained, g/kg /day
% Absorbed N retained
% Consumed N retained
Tl
87.
69.
12.
58.
7.
2.
4.
64.
37.
1
3
4
6
0
1
9
6 '
9
T2
84.
79.
11.
70.
8.
2.
6.
70.
50.
THREE OF
1
8
4
0
2
5
7
6
7
T2
84.
74.
11.
65.
7.
2.
5.
68.
44.
2
1
9
4
4
4
0
9
0
T3
89.
78.
12.
68.
8.
2.
6.
77.
53.
TRIAL
2
2
9
0
7
4
3
7
8
T3
89.
73.
12.
61.
7.
2.
5.
70.
44.
1
3
5
8
6
0
6
0
1
3
1
3
5
7
7
2
5
9
0
T4
84
78
11
65
7
2
5
64
42
T4
84
74
11
61
7
2
4
66
40
SEM
.2
.0
.7
.8
.7
.7
.0
.5
.6
2
3
0
0
0
4
4
.4
.1
.4
.3
.6
.5
.5
SEM
.2
.9
.7
.0
.2
.4
.8
.0
.7
2
3
0
0
0
4
4
.3
.1
.5
.3
.6
.4
.2
58
-------
retention values noted in the previous weeks. Although there were no signi-
ficant differences (P>.05) among any of the treatments in efficiency of N
utilization, lambs fed the 2 and 4% urine rations retained the most protein
whether expressed as grams per day, % absorbed or % consumed N retained.
Lambs fed the 0 and 6% urine rations retained similar amounts of N.
Week 4.
Treatments did not differ (P>.05) in dry matter and crude protein in-
takes or digestibilities in week 4 (Table 33). The grams of net protein
retained during week 4 on the 0, 2, 4 and 6% urine rations were (P<.05) 3.8,
5.0, 5.3 and 4.8 g per day, respectively. These would compare with 4.7,5.3,
5.5 and 4.8 g per day, respectively, in week 3. The percent of absorbed
and consumed N retained was also lower for all treatments in week 4. This
was likely due to the increased positive protein status of the animals by
this time. Lambs fed the 2, 4 and 6% urine rations retained a (P<.05)
higher percentage (39.8, 43.0 and 39.9%, respectively) of consumed N than
lambs fed the 0% ration (31.0%). Percent absorbed N retained appeared
similar to consumed N retained. In general, N utilization was still
slightly more efficient for lambs fed the 4% urine ration.
TABLE 33. N BALANCE FOR WEEK FOUR OF TRIAL 3.
Item
Dry matter intake, g/kg ' /day
Dry matter digestibility, %
Crude protein intake, g/kg ' /day
Crude protein digestibility, %
Crude protein absorbed, g/kg " /day
Urinary crude protein excreted, g/kg
/day
0.75
Crude protein retained, g/kg /day
% Absorbed N retained
% Consumed N retained
Tl
86.2
70.4
12.3
59.2
7.3
.75
3.4a
3.8a
52. 6a
31. Oa
T2
89.3
74.3
12.6
65.1
8.2
3.2a»c
V
5.0b
61.2a'b
39. 8b
T3
88.3
71.5
12.4
62.0
7.7
2.4b
,
5.3
69. lb
43. Ob
T4
86
73
12
61
7
2
4
65
39
SEM
.4
.1 2.2
.0
.4 2.6
.4 0.4
V p
.6b>°0.2
a b
.8 ' 0.3
.2b 2.9
b
.9 2.4
Values in a row with different superscripts differ significantly
(P<.05).
Week 5
By the fifth week, all of the lambs had repleted their N reserves to a
59
-------
point that was near normal for their physiological growth status (Table 34).
Therefore, as noted in Table 34 and Figures 2 and 3, N response parameters
were essentially the same on all treatments. All rations were about equally
efficient in meeting the daily N requirement, and differences in N retention
were less apparent than in the preceding four weeks.
TABLE 34. N BALANCE FOR WEEK FIVE OF TRIAL 3
Item Tl T2 T3 T4 SEM
0.75
Dry matter intake, g/kg /day
Dry matter digestibility, %
Crude
Crude
Crude
protein intake,
g/kg ' /day
protein digestibility, %
protein absorbed
/i 0.75..
, g/kg /day
86.
72.
12.
63.
7.
2
6
3
3
8
89
72
12
63
8
.3
.8
.6
.8
.0
88.
74.
12.
65.
8.
3
9
4
7
1
86
73
12
62
7
.4
.7
.0
.1
.4
2.6
3.2
0.5
Urinary crude protein excreted, g/kg
/day
0. 75
Crude protein retained, g/kg ' /day
% Absorbed N retained
% Consumed N retained
2.9
4.8
62.4
39.3
3.0
5.1
63.4
40.3
3.1
5.1
62.1
41.0
2.8
4.6
61.5
38.5
0.4
0.5
4.4
3.5
Five Week
Figure 2 shows the treatments to differ widely during the first week
of the repletion phase in percent absorbed N retained, but to equalize by
the end of the fifth week. Grams of protein retained per day followed a
similar pattern (Figure 3). When the N balance data was averaged over the
five week repletion phase (Table 35), daily dry matter and crude protein
intakes for the 0, 2, 4 and 6% urine rations were 86.7, 86.1, 88.0 and 84.9
g/day, respectively for dry matter and 12.3, 12.2, 12.4 and 11.8 g/day,
respectively, for protein. Dry matter digestibilities ranged from 73.6 to
76.9% (P>.05). The 6% urine ration had a lower (P<.05) protein digestibil-
ity (63.1%) than the 2 (68.1%) and 4% (67.4%) urine rations. Protein di-
gestibility on the 0% urine ration (63.8%) was lower (P<.05) than on the 2%
urine ration. Lambs fed the 6% urine ration absorbed less (P<.05) protein
(7.5 g/day) than lambs fed the 2 (8.2 g/day) and 4% (8.4 g/day) rations.
Although protein excretion in the urine did not differ (P>.05) among
rations, the 4% urine ration was the lowest. Grams of protein retained per
day were higher (P<.05) on the 2 and 4% urine rations than on the 6% urine
ration (5.6 and 6. 1 vs 4.8 g/day). Lambs fed the 4% urine ration retained
a higher (P<.05) percentage of absorbed (72.1%) and consumed N (49.0%) than
lambs fed the 0 (65.5 and 42.1%) and 6% urine rations (63.9 and 40.5%).
60
-------
In general, the 5-week treatment averages were less profound than in the
early weeks, but the trends were the same.
TABLE 35. N BALANCE SUMMARIZED OVER THE FIVE WEEK PERIOD
Item
Dry matter intake, g/kg°*75/day1>2
Dry matter digestibility, %
Crude
Crude
Crude
protein
protein
protein
Urinary crude
Crude
/day
protein
intake ,
g/kg°-75/day
digestibility, %
absorbed
protein
retained
, g/kg ' /day
excreted, g/kg
/i 0.75..
, g/kg /day
% Absorbed N retained
% Consumed N retained
Tl
86.7
73.6
12.3
63.8a»c
7.9a'c
.75
2.7
5.2a'b
65. 5a
42.1a'b
T2
86.1
76.5
12.2
68. lb
8.2b'c
2.7
5.6b>d
£ "7 O** 9 ^
D/ . Z
46.0b»c
T3
88
76
12
67
8
2
6
72
49
.0
.9
.4
,4b,c
.4b,c
.3
.lC'd
.lb'C
.Oc
T4
84
75
11
63
7
2
4
63
40
.9
.6
.8
.1
.5a
.6
.8a
.9a
.5a
SEM
1.1
1.4
0.2
0.1
0.2
1.8
1.7
Values represent the mean of 20 observations per treatment.
Values in a row with different superscripts differ significantly
(P<.05).
General Conclusions
1. For unknown reasons, ration digestibility was greatest during the
first two weeks following the depletion phase. This implies that physiolog-
ical or nutritional status of the animal may influence digestive efficiency-
greatest efficiency being observed in thin animals in poor condition.
2. Greatest N retention efficiency was observed during the first two
weeks when the lambs were still in a very depleted N state.
3. In general, the greatest N retention efficiency was observed on
the 4% urine ration, particularly during the first several weeks. Never-
theless, the differences were not great between the 0, 2 and 4% urine
rations .
4. In general, the 6% urine ration promoted the poorest N retention
efficiency especially during the first several weeks. Little difference
was noted, however, by the end of the fifth week. This was due to the fact
61
-------
that N retention efficiency on the 6% urine diet tended to remain constant
over the 5 week period while N retention on the other three treatments de-
clined. This response may be an indication of an adaptation response, but
more likely merely reflects compensatory N repletion in that the 6% treat-
ment produced the poorest N retention during the first two weeks; thus, these
animals merely took longer to replete their N reserves.
5. It is not clear why the responses were slightly better throughout
most of the study on the 4% urine treatment. Since there were only 4 lambs/
treatment, possibly by chance more vigorous, genetically superior animals
in growth rate (hence, greater ability to store or retain protein in muscle
growth, etc.) were allotted at random to this treatment, biasing the results.
6. When the lambs had repleted their protein reserves by the fifth
week, there were no differences or trends evident in N efficiency among
treatments.
7. Urinary N appears to be readily available for incorporation into
microbial protein synthesis in the rumen. Certainly, it was not anticipated
that the N retention efficiencies from urine would look as favorable as they
did.
8. Since these lambs were fed ad lib they likely consumed small
quantities of feed at any one time and ate frequently (nibblers) throughout
the day. In theory, such a feeding arrangement would favor better NPN util-
ization since low levels of the NPN source (in this case urine) would be
consumed at one time. This would result in moderately low, relatively con-
stant NHo levels in the rumen, rather than having large peaks in NHg concen-
tration (and resulting wasteage) shortly after feeding as when lambs are fed
one or two times daily (meal eaters). A low, continuous supply of NIL,
would be more favorable for efficient incorporation of NH-j into microbial
protein synthesis and result in reduced NH3 losses via absorption into the
blood, reconversion of absorbed NEL to urea in the liver and excretion of
urea via the urine. Moreover, it should be noted that the diet used in
these studies contained a reasonably good source of readily available carbo-
hydrates or energy, providing for favorable microbial protein synthesis
from NPN. Nevertheless, it is somewhat surprising that the N retention
data looks as favorable as it does on the urine diets, particularly the
higher levels. Possibly the favorable N retention data (relative to soybean
meal) can be explained by the manner of feeding. It would be interesting
to ascertain N response parameters under different feeding arrangements.
62
-------
SECTION VIII
TRIAL 4—DIGESTION AND GROWTH STUDY WITH LAMBS
SUMMARY
Trial 4 was a growth and metabolism study comparing rations containing
0, 20, 40 and 60% feces as a roughage source for lambs.
In general, dry matter, organic matter, ash, crude protein, acid deter-
gent fiber, cellulose and neutral detergent fiber digestibilities decreased
with increasing feces levels although the differences were not always signi-
ficant. Dry matter digestibilities were 45.3, 40.7, 37.0 and 29.2% on the
0, 20, 40 and 60% feces rations, respectively (P<.05).
There were no significant (P>.05) differences among treatments in
chlorine and phosphorus retention. Calcium and phosphorus intake and ex-
cretion increased with feces level in the diet. All of the mineral reten-
tion values appeared normal.
Daily dry matter intakes were slightly higher (P<.05) for lambs fed
the control ration (1.17 kg) as compared to those fed the 20% (1.06 kg), 40%
(1.07 kg), and 60% (1.07 kg) feces rations. In general, intakes and pala-
tabilities of the feces rations appeared much better than anticipated.
Average daily gain decreased (P<.05) slightly with each higher increment of
feces. The values were 0.06, 0.03, 0.01 and -0.02 kg gain per day (89 days)
on the 0, 20, 40 and 60% feces rations, respectively. Although the data
herein suggest that feces are low in energy, all of the levels of feces used
in this trial appeared acceptable for maintenance type programs.
INTRODUCTION
The purpose of this trial was to determine the effect of increasing
levels of feces upon nutrient digestibility, ration palatability and lamb
growth rate.
EXPERIMENTAL PROCEDURES
The rations used in this trial are shown in Table 36. Dried steer
feces were incorporated into four lamb growing rations (treatments) at levels
of 0, 20, 40 and 60% as a replacement for 10% dehydrated alfalfa and 10%
cottonseed hulls for each 20% increment in feces level. Forty-eight young,
Western lambs weighing an average of 23.4 kg were randomly allotted to one
of the four treatments making a total of twelve lambs per treatment. The
63
-------
lambs were adapted over a two week period to .the rations which was followed
by a 89-day growth study. The lambs were fed ad libitum daily in individual
pens, and feed weighbacks were recorded weekly. Water was always available.
After the seventh week on trial, four lambs were chosen at random from
each of the treatments and placed in individual digestion stalls. Daily
feed levels were adjusted to a constant daily ad libitum intake. After a
10-day adjustment in the stalls, a 7-day digestion study was conducted.
During the digestion study, total outputs of feces and urine were collected,
weighed and sampled daily. The individual daily samples for each lamb were
then composited. The feces samples were dried and ground as described in
Trial 3. Laboratory procedures were as outlined in Trial 1 except Kjeldahls
were done only on the dried feces.
Ration digestion coefficients and growth performance data were calcu-
lated in the conventional manner. Statistical analyses were done using
analysis of variance with significant differences among means being tested
by least significant differences (LSD).
TABLE 36. COMPOSITION OF THE RATIONS FED IN TRIAL 4
Ingredient
Feces Level
20 40
60
Dehydrated alfalfa meal, 1-00-025
Cottonseed hulls, 1-01-599
Dried feces
Traced mineral salt
65.5
34.3
0.2
55.1
24.3
20.4
0.2
44.8
14.4
40.5
0.2
34.7
4.7
60.4
0.2
Proximate Analysis :
Dry matter
Ash
Crude protein
Acid-detergent fiber
Lignin
Cellulose
Neutral detergent fiber
Sodium
Chlorine
Calcium
Phosphorus
93.6
12. a
14.3
42.9
11.0
30.8
58.5
0.49
0.64
1.24
0.27
92.8
13.2
15.5
40.9
15.1
28.6
57.8
0.30
0.53
1.30
0.40
93.4
18.7
16.5
40.9
14.0
25.0
56.7
0.55
0.68
1.56
0.59
93.6
26.7
17.0
47.5
12.9
20.4
59.3
0.45
0.59
1.66
0.72
Dry matter basis.
RESULTS AND DISCUSSION
Ration Digestibilities
Dry matter digestibility for the 0% feces control ration (45.3%) did
64
-------
not differ (P>.05) from the 20% ration (40.7%), but was higher (P<.05) than
for the 40% (37.0%) and 60% (29.2%) feces rations (Table 37). Moreover, the
dry matter digestibility of the 40% feces ration was significantly higher
(P<.05) than the 60% feces ration. The 0% feces ration had the highest
(P<.05) ash digestibility (34.2%). Ash digestibility for the 40% feces
ration (12.2%) was similar (P>.05) to the 20% feces ration (7.1%) but
higher (P<.05) than the 60% (-2.4%) feces ration. The low ash digestibili-
ties on the feces rations can be attributed to the high ash content in the
feces. Rations did not differ (P<.05) in organic matter or crude protein
digestibility. Digestibilities for these parameters were approximately
40-48% for all treatments.
Acid detergent fiber (ADF) digestibilities were similar on the 0 and
20% feces rations (24.0 and 18.7, respectively), but the 0% feces ration
was higher (P<.05) than the 40% (14.7%) and 60% (10.7%) feces rations. As
in Trial 2, lignin digestibility (-2.2%) was the lowest (P<.05) for the 0%
feces ration, but the 20, 40 and 60% feces rations did not differ (P>.05)
in lignin digestibility (approximately 20%). There were no significant
(P>.05) differences in cellulose digestibility, but neutral detergent fiber
(NDF) digestibility decreased (P<.05) with increasing feces level in the
diet. In general, dry matter, organic matter, crude protein, ADF and NDF
digestibilities decreased with each increase of feces in the ration.
TABLE 37. APPARENT DIGESTIBILITIES OF RATIONS IN TRIAL 4.
Feces Level
0 20 40 60 SEM
Apparent digestibilities
10
Dry matter 1»z
Ash
Organic matter
Crude protein
Acid detergent fiber
Lignin
Cellulose
Neutral detergent fiber
45. 3a
34. 2a
46.7
48.2,
24. 0D
rt
-2.2a
40.4
37.2°
40.7a'b
7.1b'C
45.6
46'°a b
18.7a'b
23.5
43. lb c
33.0 '
/o
37. Ob
12. 2b
42.6
44.7
14.7*
20.1
40. 5b
27.6
29. 2C
-2.4°
40.4
43. 4a
10. 7b
18.6
36. Oa
18.2
2.4
4.5
2.2
2.1
2.9
4.2
2.4
3.0
Values with different superscripts in a row differ significantly
(P<.05).
2
Values represent the mean of four lambs.
Mineral Retention and Excretion
Sodium retention (Table 38) was highest (P<.05) on the 0% feces ration
(2.26 g/day). Each higher increment of feces, after 20%, resulted in a
higher (P<.05) retention of sodium. Sodium retention for the 20, 40 and
65
-------
60% feces ration was -1.42, 0.44 and 1.15 g/day, respectively. There were
no significant (P>.05) differences among treatments in chlorine and phospho-
rus retention, but tended to be slightly higher on the control diet (0
feces). In general, there was a slight negative Ca retention on the three
feces diets. All of the mineral retention data, however, would be regarded
as normal values. There were no substantial differences in sodium and
chlorine intake and/or fecal excretion regardless of treatment. This should
be expected since those are normally excreted predominately in the urine.
For Ca and P, however, both intake and fecal excretion increased as feces
in the diet increased. This is logical and as should be expected consider-
ing the normal avenues of excretion as discussed in Trial 2.
TABLE 38. MINERAL RETENTION DATA IN TRIAL 4
Intake
Fecal excretion
Urine excretion
Net retention
Intake
Fecal excretion
Urine excretion
Net retention
Intake
Fecal excretion
Urine excretion
Net retention
Intake
Fecal excretion
Urine excretion
Net retention
0
5.78
1.03
2.49,
2.26d
7.62
0.31
6.69
0.62
14.64
13.49
1.15b
3.15
2.52
0.39
0.24
20
3.46
1.02
3.86
-1.42a
5.99
0.41
5.96
-0.38
14.82
16.44
-1.62a
4.58
4.38
0.40
-0.20
Feces Level
40
Sodium
6.33
1.24
4.65,
0.44b
Chlorine
7.86
0.54
7.00
0.32
Calcium3
17.98
18.76
-0.78a
Phosphorus
6.76
5.52
0.86
0.38
60
5.03
1.37
2.51
1.15C
6.50
0.70
5.46
0.34
18.35
19.19
-0.84a
7.99
6.51
1.07
0.41
SEM
0.2
0.2
0.5
0.2
a C ' Values with different superscripts in a row differ significantly
(P<.05).
2
Values represent the mean of four lambs.
o
Calcium was not analyzed in the urine as the majority is excreted in the
feces.
66
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Growth Performance
Daily dry matter intake was highest (P<.05) on the 0% ration (1.17 kg/
day), as shown in Table 39. The three feces rations produced about 0.10 kg
lower (P<.05) intakes, being 1.06 (20), 1.07 (40) and 1.07 kg (60) dry mat-
ter intake/day. Average daily gain (89 days) on the 4 treatments were 0.06,
0.03, 0.01 and -0.02 kg on the 0, 20, 40 and 60% rations, respectively.
Each additional level of feces cause a significant (P<.05) decrease in gain,
although the actual magnitude of decrease was very small. The growth data
in this study suggests that the energy content of feces is low, but that
rather large amounts of feces could be incorporated into maintenance type
rations. No adverse problems were encountered in achieving satisfactory
intakes on the feces diets. This was evidenced by intakes in excess of
4.0% of body weight on all diets. Adaptation to such diets was successfully
achieved in about one week. The ground feces used in this study were very
dry and dusty. Perhaps, even better acceptance might be obtained if the
feces rations were pelletted.
TABLE 39. GROWTH DATA ON LAMBS IN TRIAL 4
Number of lambs
Beginning weight, kg
Ending weight, kg
Dry matter intake, kg/day
Average daily gain, kg/day
0
12
23.3
28.9
1.17a
0.06
Feces Level
20 40
12
23.6
26.6 b
1.06°
0.03
12
23.6
24.1
1.07°
0.01
60
12
23.3
21. 3 b
1.07d
-0.02
SEM
17.5
.01
a c ' Values with different superscripts in a row differ significantly
(P<.05).
67
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SECTION IX
TRIAL 5--HEIFER GROWTH TRIAL
SUMMARY
A 109-day feedlot growth trial was conducted with heifers to compare
three treatments: Tl) basal containing 88% concentrate, T2) basal plus 15%
dried steer feces and, T3) basal plus 15% dried steer feces and 1% partially
dried steer urine. The feces were substituted for corn in the basal ration,
and the urine was substituted for soybean meal on an iso-nitrogenous basis.
Heifers fed the control, basal ration (Tl) consumed slightly more feed
(P>.05) than.heifers fed the 15% feces (T2) and feces plus urine (T3)
rations (6.03 vs 5.70 and 5.75 kg, respectively). The respective average
daily gains were 1.13, 0.87 and 0.92 kg. The feed/gain values were 5.33,
6.59 and 6.28 on Tl, T2 and T3, respectively.
INTRODUCTION
The purpose of this trial was to determine the feedlot performance of
growing cattle fed high concentrate rations containing feces or feces plus
urine.
EXPERIMENTAL PROCEDURES
Twenty-seven 6-8 month old heifer calves weighing an average of 177.8
kg were randomly assigned to one of three treatments with nine heifers per
treatment (three pens per treatment and three heifers per pen). The treat-
ments compared (Table 40) were: Tl) basal ration containing .88% concentrate,
T2) basal ration plus 15% dried steer feces, and T3) basal ration with 15%
feces plus 1% partially dried steer urine (T3). In T2 and T3 feces and/or
urine were substituted for corn in the basal ration. The nitrogen in the
urine replaced an equivalent amount of supplemental nitrogen supplied by
soybean meal. All rations were intended to be iso-nitrogenous. A three
week ration adaptation period was followed by a 109-day growth trial. The
heifers were fed ad libitum, and feed weighbacks were taken weekly on each
pen. Water was always available.
RESULTS AND DISCUSSION
Heifers fed Tl consumed slightly more feed (P>.05) than heifers fed T2
or T3 (6.03 vs_ 5.70 and 5.78 kg day, respectively) as shown in Table 41.
Average daily gain was higher (P<.05) for heifers, fed Tl (1.13 kg/day) than
68
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those fed T2 or T3 (0.87 and 0.92 kg/day, respectively). Although there
were no significant differences (P>.05) among treatments in feed efficiency,
heifers fed the control required less feed per kilogram of gain (5.33, 6.59
and 6.28 on Tl, T2 and T3, respectively).
When calculating the amount of ration other than feces and/or urine
(non-feces portion) required/unit of gain, it is evident that about the same
amount of non-feces ration was required whether feces were added or not
(5.33, 5.54 and 5.28 for the control (Tl), feces (T2) and feces plus urine
treatments (T3), respectively). Thus, in this particular case, feces did
not contribute materially to a reduction in the amount of basal ration re-
quired per kilogram of gain. However, it must be pointed out that lower
gains (as obtained on T2 and T3) automatically result in some increase in
feed requirements/unit gain since maintenance energy costs (although fixed)
are not diluted over as much gain/day. Hence, maintenance energy feed re-
quirements will increase/unit of gain as gain is reduced since maintenance
is a fixed cost/day. Moreover, feces replaced corn which is higher in
energy (NEg) than the remaining basal ration components. Hence, these two
factors can bias the data if they are not considered, resulting in the im-
pression that feces have a lower energy value than it may have actually had
or that the feces made less contribution in feed energy replacement than it
really did.
TABLE 40. COMPOSITION OF RATIONS FED IN TRIAL 5
Ingredient1 Tl T2 T3
Ground corn, 4-02-935 78.8 63.1 63.6
Cottonseed hulls, 1-01-599 7.6 7.5 7.5
Dehydrated alfalfa meal, 1-00-025 5.2 5.1 5.1
Liquid molasses, 4-04-696 1.9 1.9 1.9
Soybean meal, 5-04-604 5.1 5.0 3.5
Dried feces 15.9 15.9
Dried urine 1.0
Calcium carbonate, 6-02-632 0.9 0.8 0.8
Dicalcium phosphate, 6-01-080 0.3 0.3 0.3
Salt 0.3 0.3 0.3
Aurofac-50 + + +
Vitamin A + + +
Dry matter basis.
Although the rations were consumed readily, it can be concluded that
overall growth performance was lowered somewhat when feces were included at
a 15% level in a feedlot growing ration for heifers. In this experiment,
the corn was ground rather fine, and the feces were also finely ground and
somewhat dusty. Such factors can cause reductions in intake. Had the corn
and feces been rolled or ground to give a large particle size, better in-
69
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takes and gains might have been achieved on the feces diets. When feces are
added to a high corn diet as in this instance, perhaps it is utilized with
a different efficiency (lower) than when combined into lower quality rations
(e.g. roughage). Source of the feces is also undoubtedly important. The
feces in this study were obtained from rations in which the starch digesti-
bility in steers was experimentally determined to be 99%+. In this respect,
starch digestibilities under field conditions would normally be lower than
this (perhaps 85-94%), and hence, the feces from high concentrate rations
would normally be expected to be somewhat higher in indigested starch con-
tent than in this study—resulting in a higher potential refeeding value.
TABLE 41. GROWTH DATA ON HEIFERS IN TRIAL 5
Rations1 Tl T2 T3 SEM
Number of heifers 999
Beginning weight, kg 178.1 177.8 177.6
Ending weight, kg 301.6 273.0 276.4
Daily feed intake, kg/day
Basal2 6.03 4.79 4.86
Feces 0.91 0.92
Total3 6.03 5.70 5.78 0.37
Average daily gain, kg/day
Basal 1.13 0.73 0.77
Feces 0.14 0.15,
Total 1.13a 0.87° .92 0.06
Feed efficiency, kg feed/kg gain
Basal
Feces
Total
5.33
5.33
5.54
i ns
6.59
5.28
i on
6.28
0.41
1 Tl is the control, T2 contains feces and T3 contains feces plus urine.
2
In T2 and T3, feces replaced corn rather than a percentage of the basal
ration.
Sab:
Values with different superscripts in a row differ significantly
(P<.05).
70
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SECTION X
REFERENCES
Anthony, W. Brady and Ronald Nix. 1962. Feeding potential of reclaimed
fecal residue. J. Dairy Sci. 45:1538.
Anthony, W. Brady. 1966. Utilization of animal waste as feed for ruminants.
Proc. Natl. Symp. Anim. Waste Manage. ASAE Publ. No. SP-0366:109.
Anthony, W. B. 1967. Manure-containing silage-production and nutritive
value. J. Anim. Sci. 26:217 (Abstr.).
Anthony, W. B. 1968. Wastelage—a new concept in cattle feeding. J. Anim.
Sci. 27:289 (Abstr.).
Anthony, W. Brady. 1969. Cattle manure: Re-use through wastelage feeding.
Proc. Conf. Anim. Waste Manag., Cornell Univ., Ithaca, NY, p. 105.
Anthony, W. Brady. 1970. Feeding value of cattle manure for cattle. J.
Anim. Sci. 30:274.
Anthony, W. B. 1971. Cattle manure as feed for cattle. In livestock waste
management and pollution abatement. Proc. International Symp. on
Livestock Wastes, Columbus, Ohio, p. 293.
Albin, R. C. and L. B. Sherrod. 1975. Nutritional value of cattle feedlot
waste for growing-finishing beef cattle. In managing livestock
wastes: Proc. 3rd International Symp. on Livestock Wastes,
Urbana-Champaign, Illinois, p. 211.
Bandel, Linda Sue and W. B. Anthony. 1969. Wastelage-digestibility and
feeding value. J. Anim. Sci. 28:152 (Abstr.).
Flegal, C. J., C. C. Sheppard and D. A. Dorn. 1972. The effects of continu-
ous recycling and storage on nutrient quality of dehydrated poultry
waste (DPW). Proc. Cornell Agr. Waste Manage. Conf., p. 295.
Johnson, R. R. 1972. Digestibility of feedlot waste. Okla. Agr. Exp. Sta.
Misc. Pub. 87:62.
Johnson, R. R., R. Panciera, H. Jordan and L. R. Shuyler. 1975. Nutritional,
pathological and parasitological effects of feeding feedlot waste
to beef cattle. Proc. 3rd International Symp. on Livestock Waste;
Urbana-Champaign, Illinois, p. 203.
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Lucas, D. M., J. P. Fontenot and K. E. Webb, Jr. 1975. Composition and di-
gestibility of cattle fecal waste. J. Anim. Sci. 41:1480.
McClure, K. E., R. L. Preston and E. W. Klosterman. 1973. Digestibility and
palatability of fermented cattle manure fed to cattle. J. Anim.
Sci. 37:350 (Abstr.).
Moore, J. D. and W. B. Anthony. 1970. Enrichment of cattle manure for feed
by anaerobic fermentation. J. Anim. Sci. 30:324 (Abstr.).
Smith, L. W. , H. K. Goering and C. H. Gordon. 1969. Influence of chemical
treatments upon digestibility of ruminant feces. Proc. Conf.
Anim. Waste Manage., Cornell Univ., Ithaca, NY, p. 88.
Smith, L. W., H. K. Goering and C. H. Gordon. 1971. Nutritive evaluations
of untreated and chemically treated dairy cattle wastes. In Live-
stock Waste Management and Pollution Abatement. Proc. International
Symp. on Livestock Waste, Columbus, Ohio, p. 314.
Tinnimit, Parnich, Yu Yu, Kenneth McGuffey and J. W. Thomas. 1972. Dried
animal waste as a protein supplement for sheep. J. Anim. Sci.
35:431.
Wadleigh, C. H. 1968. Wastes in relation to agriculture and forestry.
U.S.D.A. Misc. Pub. 1065.
Ward, G. M., D. E. Johnson and R. D. Boyd. 1974. Digestibility by steers
of cereco silage produced from feedlot manure. J. Anim. Sci.
39:140 (Abstr.).
72
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-77-175
3. RECIPIENT'S ACCESSION'NO.
4. TITLE AND SUBTITLE
INFLUENCE OF RECYCLING BEEF CATTLE WASTE ON
INDIGESTIBLE RESIDUE ACCUMULATION
5. REPORT DATE
August 1977 issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Donald G. Wagner, Barbara A. Ackerson, and
Ronald R. Johnson
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Oklahoma Agricultural Experimental Station
Oklahoma State University
Stillwater, Oklahoma 74074
10. PROGRAM ELEMENT NO.
1HB617
11. CONTRACT/GRANT NO.
R-803274
12. SPONSORING AGENCY NAME AND ADDRESS
Robert S. Kerr Environmental Research Lab.-Ada OK
Office of Research and Development
U.S. Environmental Protection Agency - Ada, OK
Ada, Oklahoma 74820
13. TYPE OF REPORT AND PERIOD COVERED
Final (7/1/74 - 8/31/76)
14. SPONSORING AGENCY CODE
EPA/600/15
15. SUPPLEMENTARY NOTES
16. ABSTRACT
Studies were conducted to investigate the effect of feces recycling in beef
cattle diets (rations) on the digestibility of various dietary nutrients and on
the accumulation of indigestible residues. Feces were refed in three successive
phases based primarily upon the quantity of feces produced in the previous phase.
Several different roughage levels in high concentrate rations were considered.
An attempt was made to investigate the digestibility of various nutrient parameters
in feces when refed and the roughage value of feces. Mineral retention data and
the accumulation of various minerals in the fecal and urinary residues were
studied. Varying levels of feces in growing/maintenance rations were investigated
along with the efficiency of urinary nitrogen (N) as a supplemental N source.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COS AT I Field/Group
Beef cattle
Wastes
Recycling
Animal nutrition
Manure
Urine
02/E
13. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (ThisReport)
UNCLASSIFIED
21. NO. OF PAGES
83
20. SECURITY CLASS f This page)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
73
/Y U. S. GOVERNMENT PRINTING OFFICE: 1977-757-056/6528 Region No. 5-11
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