4, Department of Animal Science Florida Agricultural
Research Report AL-1975-4 Experiment Station
May, 1975 Gainesville, Florida
RECYCLED MODIFIED SWINE WASTES AS A SOURCE OF ;? /ii" l.I,/iitV
PROTEIN, VITAMINS AND MINERALS FOR SWINE'
H. D. Wallace, N. D. Thanh, G. E. Combs m 0., 7
and R. A. Nordstedt2
The fertilizer value of swine wastes has long been recognized. Each ton of ----
swine waste contains approximately 500 pounds of organic matter, 10 pounds of
nitrogen, 5 pounds of phosphoric acid and 10 pounds of potassium. When handling
costs and land use situations are such that it is feasible to return wastes
directly to the land much of this potential value can be realized. However, in
many modern day confinement hog operations the main concern is simply to remove
and get rid of the waste as expeditiously as possible. Thus the lagoon waste
disposal system has come to be widely used. In the lagoon system, much of the
nitrogen is lost to the atmosphere and most of the other nutrients remain in the
Swine wastes also represent a potential source of nutrients suitable for
livestock feed. Harmon (1) has stated that "swine wastes should be viewed as an
active biomass. It is a by-product of metabolism and processing, just as are
by-products of the feed industry that involve a fermentation". Without alteration,
however, raw waste is worthless as a feed. Odor is a problem and much of the
nitrogen present is in the form of non-protein nitrogen and of little nutritional
value to the pig.
The objective of this study was to develop a small model system capable of
converting raw swine wastes into a feed suitable for recycling to growing-finishing
swine. A detailed literature review and a theoretical presentation of the model
concept is found in the dissertation of Thanh (2).
1 Data presented in this report were from Swine Unit Experiment No. 238.
2 Wallace and Combs, Animal Nutritionists and Thanh, graduate assistant,
Animal Science Department; and Nordstedt, Assistant Professor of Agri-
cultural Engineering, University of Florida.
This public document was promulgated at an annual cost of
$120.00, or .04 cents per copy to inform county agricul-
tural directors, ranchers and growers of research results
in swine management and nutrition.
Department of Animal Science
Institute of Food and Agricultural Sciences
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A small scale model system was built at the University of Florida swine unit
to collect, process and distribute swine waste. The model is illustrated in
Ten pig cages in a nursery were used to house the pigs. The cages were
raised above the sloping concrete floor by legs and were equipped with expanded
metal bottoms and chain wire sides. Six cages were used for experimental groups
of pigs and four for control groups.
A holding pit was constructed by installing two partition walls in an existing
manure pit so that wastes from experimental groups could be collected separate
from the control groups. Concrete block trenches connecting the pens with the
holding pit were used to channel the flow of wastes. Wastes were hosed into the
holding pit. An outboard trolling motor was used to blend the raw manure and
maintain a water suspension as it was pumped into the fermentor.
The fermentor consisted of a 500-gallon oil drum which was placed vertically
in the ground at a depth of 80 cm. with its top end open. The raw manure was
pumped through a 1 inch pipe and a spray nozzle directed it into the fermentor.
When necessary, a paddle pump recirculated the liquid wastes through a suction
pipe at the bottom of the fermentor back to the spray nozzle so that excessive
foam formation could be prevented.
The aeration system consisted of a 2-horsepower positive displacement blower
which forced air through an air diffuser in the bottom of the fermentor. Molasses
was added to the fermentor at a level of 0.5 percent to stimulate bacterial growth.
Each day, in the late afternoon, 70-90 percent of the fermented product was
pumped from the fermentor through a screen which removed corn hulls and hog hairs,
and into a sterilization tank. Ten to 30 percent of the liquor remained in the
fermentor as an inoculum for the following culture. After sedimentation (20
minutes), the supernatant was pumped back to the fermentor, allowing 40 to 45
percent of the liquid wastes to remain in the sterilization tank. When approxi-
mately 70 gallons of the concentrated material accumulated in the sterilization
tank the temperature was elevated to 1550 F and maintained for 30 minutes. The
end-product of the fermented, concentrated and sterilized wastes (FCSW) was
allowed to cool and then pumped from the sterilization tank and offered as a
drink to the pigs. This drink replaced water in the feeding program and was
studied as a supplement to diets formulated to be deficient in certain nutrients.
Control pigs were given tap water.
Design of the feeding trial showing pig allotment and diet assignment is
given in Table 1. The composition of the dry feed mixtures is presented in
Table 2. These mixtures were offered by self feeder.
Raw manure tank
Figure 1. Processing System for Recycling Swine Wastes.
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Table 1. Number of Pigs Allotted and Diet Assignment
Diet' FCSW Control
B 10 5
C 10 5
D 10 5
complete growing-finishing diet
low in minerals
low in minerals and protein
low in minerals, protein and B-complex
Table 2. Composition of Dry Diets
Ingredient, % A B C D
Ground yellow corn 82.10 83.04 89.91 89.95
Soybean oilmeal (49%) 15.00 15.00 8.00 8.00
Dynafos (IMCC)' 1.70 0.35 0.53 0.53
Limestone 0.80 1.35 1.30 1.30
Iodized salt 0.25 0.15 0.15 0.15
Trace minerals (CCC)2 0.10 0.06 0.06 0.06
Vitamin premix (UF)3 0.05 0.05 0.05 -4
1 Product of International Minerals and Chemical Corporation,
2 Supplied by Calcium Carbonate Co., Quincy, Illinois. Con-
tained 20% zinc, 5.5% manganese, 1.1% copper, 10% iron,
0.15% iodine, 0.10% cobalt and 2% calcium.
3 Contained 6,000 mg riboflavin, 20,000 mg niacin, 12,000 mg
pantothenic acid, 80,000 mg choline chloride, 10,000 mcg
vitamin B12, 2,500,000 IU vitamin A, 400,000 ICU vitamin D3
and 10,000 IU vitamin E per lb. of premix.
4 The vitamin premix was omitted from diet D. Vitamins A, D
and E were added to this diet at same level as for other
diets, leaving diet D devoid of supplementary riboflavin,
niacin, pantothenic acid, B12 and choline chloride.
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Results and Discussion
Numerous problems were encountered in the operation of the model unit.''
Details of these trials and tribulations will not be discussed here but are well
documented in the dissertation of Thanh (2). The feeding trial lasted for a
period of six weeks. Performance of the pigs is summarized in Table 3. Pigs
fed the positive control complete diet A(C) with access to drinking water consumed
the most feed and made the most rapid gains. Pigs fed diet B(C), which was the
same as A(C) except for a reduction in mineral content, ate less and gained much
slower. When FCSW was substituted for drinking water with diet B the pigs performed
at approximately the same level as on diet B with drinking water. Differences in
gains between these three lots of pigs were not statistically significant. Gains
on diet C, which was a low mineral and low protein mixture, were significantly
(P < .05) poorer than on Diet A. Substitution of FCSW for drinking water with ..i,
Table 3. Performance of Pigs Fed Fermented, Concentrated,
Sterilized Swine Wastes (FCSW) as a Substitute
for Supplementary Protein Minerals and Vitamins
c) B(C Diets
Item A(C)l B(C) B(FCSW)' C(C) C(FCSW) D(C) DIFCSW)
Number of pigs
Av. initial wt., lb.
Av. daily gain, lb.
Av. daily dry feed
Av. dry feed per
lb. gain, Ib.
1 C= control; FCSW = Fermented,
lieu of drinking water.
5 5 10
70.9 71.0 71.0
1.60 1.38 1.39
71.0 71.0 70.9 70.9 .
1.29 1.22 1.24 1.00
waste offered in
.;- *' 7'
Diet C caused a further slight reduction in daily gain. When a diet low int'.
minerals, low in protein and with no B-complex vitamin supplementation was' fferedc
with drinking water gains were similar to those obtained with diet C. When FCSW
was substituted for water with this diet gains were significantly depressed
(P < .05) with an average daily gain of only 1 lb. per day. Under the conditions'
of this experiment the FCSW was not able to effectively replace the missing nutrients
or combinations of missing nutrients. In fact it must be concluded that the FCSW
was generally, of itself, a growth depressing factor in this experiment. Nutri-
tive composition of the FCSW suggested that it should have feeding value as a
source of mineral and protein. The fermentation and concentration process altered
nutrient composition of the raw wastes as shown in Table 4. The adverse effects
from feeding this material were undoubtedly related to a failure to attain and
maintain a totally wholesome and palatable material during the study. The method
of feeding, in open troughs, was unsatisfactory since a certain degree of urine
h : ~,
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and fecal contamination was encountered. In general, notwithstanding numerous
Tittle probTems, the equipment model functioned as desired, and with further
developwmnt and adaptation might provide a means of directly cycling swine wastes
back through the pig. The main challenge remains to create a feed material from
the raw waste which can provide needed nutritional value economically. This
experiment fell far short of that goal.
Table 4. Dry Matter, Ash, Nitrogen, and Biochemical Oxygen
Demand (B.O.D.) of the Liquid Raw Wastes, 24-Hour
Fermented Liquid and FCSW
Liquid raw 24-hour FCSW
Drymatter, g/00 ml 2.48 1.58 1.87
Aqh, g/100 ml 0.42 0.39 0.46
Ash, % of dry matter 17.09 24.51 24.51
Nonprotein N, ppm 268.8 187.6 226.8
Protein N, ppm 369.6 436.9 657.4
Total N, ppm 638.4 624.5 884.2
g, rppM (5-day) 8800.0 5000.0 7800.0
I Samples were collected for analysis on the 20th and 21st day of the experiment.
A model system was constructed to collect raw swine wastes for aerobic
fermentation, concentration, sterilization and dispersal back to growing-finishing
pigs as a feed supplement. The fermented liquid product was substituted for
drinking water and used as a supplement to meal diets deficient in mineral, pro-
tein, and vitamins. A total of fifty pigs were involved and the feeding trial was
of six weeks duration.
The model system was successfully developed to a stage where the raw wastes
were recycled through a workable system. However, treatment technique, volume
control, changes in mineral concentration and other factors affecting the produc-
tion qf a consistently wholesome product of meaningful nutritional value were not
adequately mastered. Pigs offered the FCSW as a supplement to a low mineral diet
performed similarly to control pigs on the low mineral diet but not as well as
pigs fed a complete diet. The FCSW also failed to improve performance of pigs
fed a lw mineral, low protein (8%) diet. When a low mineral, low protein, low
Brcomples vitamin diet was supplemented with FCSW the result was a further reduc-
tion in feed intake and gains.
The conversion of NPN to protein nitrogen was not an efficient process.
Procedural changes will be needed to improve this conversion.
1, Harmon, BT G. and D. L. Day. 1973. Recycled swine waste as feed. Univ.
of Ill. Agr. Expt. Stat. 15(3):14.
2. Thanh, D. N. 1974. Recycled modified swine wastes as a source of protein,
vitamins and minerals for swine. University of Florida dissertation.