Underutilized Resources as Animal Feedstuffs (1983)

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Animal Wastes INTRODUCTION Excreta contain several nutrients that are capable of being utilized when the material is recycled by feeding. Nitrogen, which is present in both protein and nonprotein forms, is a major constituent, and others are cal- cium and phosporus. Certain vitamins are synthesized in the intestine and appear in the excrete. The excrete also has energy value. Coprophagy was recognized as a normal physiological phenomenon in rabbits (Madsen, 1939), and is natural in many wild and domestic species (Bjhornhog and Sjoblom, 1977~. The first documented evidence of the importance of intestinal bacterial synthesis in nutrition was probably the work of Osborne and Mendel (1914), demonstrating that feeding 1 percent feces from normally fed rats to rats on a purified diet prevented death. Bohstedt et al. (1943) found that cow manure had nutritional value for pigs, in addition to the grain it contained. Fuller (1956) reported that hydrolyzed poultry litter was as effective as fish meal in achieving Growth from commercial type broiler diets. Utilization of animal wastes as feedstuffs is not a new phenomenon. In 1925 Evvard and Henness reported that on the average one pig following 1.9 steers recovered the equivalent of 142 kg of corn during the 120-day feeding period. There have been a number of previous reviews on feeding animal waste (Anthony, 1971; Bhattacharya and Taylor, 1975; Blair and Knight, 1973; For~tenot and Jurubescu, 1980; Smith and Wheeler, 19791. 121

1 22 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS QUANTITY Van Dyne and Gilbertson (1978) estimated that 112 million tons of manure dry matter were voided by farm animals in the United States in 1974, of which about 50 percent is recoverable. The quantities produced and col- lectable by classes of animals are shown in Table 29. Although cattle wastes account for about 80 percent of the total, only 41 percent is re- coverable. Virtually all of the poultry waste is collectable. These estimates are lower than those of Heichel (1976), who estimated that 300 million tons of animal waste dry matter were produced per year, of which 50 percent was collectable. Other estimates were approximately 2 billion tons on a fresh basis (Taiganides and Stroshine, 1971; Wadleigh, 19681. As- suming a dry-matter content of 15 percent, this represents 300 million tons of dry matter. The amount of animal-waste dry matter available annually in Canada . is estimated to be 24 million tons (Pequegnat, 19754. PHYSICAL CHARACTERISTICS The wastes from farm livestock are of two types, solid and liquid. Gen- erally, these are collected separately, unless automated systems involving pits are used. Poultry do not excrete urine separately, and the waste in this case is a semisolid mixture of feces and urine. Because of the different systems of urinary excretion in livestock and poultry, a large part of the urinary nutrients tend to be lost from livestock wastes and retained with poultry wastes. Table 30 shows a partition of the nitrogen between feces and urine of various farm animals. An addi- tional factor preventing loss of nitrogen in poultry waste is the form in which nitrogen is excreted in the urine, namely insoluble uric acid. Wastes containing bedding or floor litter tend to be drier and may contain absorbed urinary waste. In the case of deep litter from poultry houses, the waste is frequently very dry and dusty. Handling of raw wastes tends to be difficult since they are either very wet or very dry. In this report, cattle waste is defined as the solid waste from beef or dairy cattle. This waste may contain litter bedding material and appreciable levels of soil if animals are housed on dirt lots. Swine wastes from con- finement herds are generally collected into pits and are frequently treated by a variety of aerobic systems to reduce odor and biological oxidation demand (BOD). Poultry wastes are generally of two types, with or without litter material. The latter, from caged birds, is referred to in this report as caged layer waste. Commonly, it contains shed feathers, spilled feed, broken eggs, etc., in addition to excretory products. Litter waste is from birds grown

Animal Wastes 123 TABLE 29 Livestock and Poultry Waste Production in the United States, 1974 Manure (1,000 tons, dry basis) Class of Animal Production Collectable Beef cattle (range)52,0571,897 Feeder cattle16,42816,000 Dairy cattle25,21020,358 Hogs13,3605,538 Sheep3,7961,700 Laying hens3,3743,259 Turkeys1,251983 Broilers2,0862,434a Total111,56252,169 aIncludes litter. SOURCE: Van Dyne and Gilbertson (1978). under floor-raising systems and contains bedding material such as peanut or rice hulls, wood shavings, sawdust, or straw. Usually litter is obtained from broiler and turkey houses. Generally it contains some feathers and spilled feed. This type of waste is referred to in this report as poultry litter waste. NUTRITIVE VALUE Chemical Composition of Animal Wastes Composition of animal wastes is shown in Appendix Tables 1 to 5. Most of the data refer to processed wastes, since raw wastes are generally unsuitable in recycling systems. One notable feature of all of these wastes is variability in composition due to dietary regime, length of time before collecting, admixture with bedding, processing method, etc. Gilbertson et al. (1974) have outlined some of the factors affecting the nutrient and energy composition of beef cattle feedlot waste fractions. Mean compositions of animal wastes (based on the data in Appendix Tables 1 to S) are shown in Tables 31 to 34. They are characterized as having a relatively high content of crude protein (high nonprotein nitrogen)  and a level of true protein that may be similar to that of the common feed grains. Other proximate constituents present at relatively high levels in

124 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS TABLE 30 Distribution of Nitrogen in Feces and Urine from Livestock Total Nitrogen (Jo) Species Feces Urine Beef cattle 50 50 Dairy cattle 60 40 Sheep 50 50 Swine 33 67 Poultry 25 75 SOURCE: Smith (1973). animal wastes are ash and fiber. Ether extract values are generally low. These features result in a relatively low level of available energy in animal wastes. The high ash content suggests that animal wastes are potentially good sources of minerals. Phosphorus is a valuable constituent. These features indicate that animal wastes are more suited to recycling systems involving ruminants, since ruminants possess a digestive tract capable of efficiently utilizing fiber and nonprotein nitrogen. The wastes possessing the highest nutritive value appear to be broiler litter and layer waste. The main difference in composition between raw and processed wastes is in moisture content; many of the processed wastes are low in moisture. Some volatile components, such as nitrogen, are also lower in some processed wastes because of losses during heating. In general, on a dry- matter basis, processed wastes share many of the characteristics of raw wastes. Nutrient Utilization Newton et al. (1977) conducted a nutritional evaluation of wastelage, a term introduced by Anthony (1970) to denote a mixture of fermented or ensiled cattle waste and a foodstuff such as forage containing 57 percent fresh cattle waste. Apparent digestibility of a control diet consisting of corn, Bermuda grass, and urea was 76.1 percent and did not differ sig- nificantly from that of a wastelage diet that was 73.7 percent. Dry-matter digestibility of fermented waste (by extrapolation) was 57.7 percent, ni- trogen digestibility was 34.2 percent, crude fiber digestibility was 31.6 percent, and digestibility of nitrogen-free extract was 83.5 percent. Harps- ter et al. (1978) reported that nitrogen retention and digestibility of dry matter, organic matter, ether extract, nitrogen-free extract, and energy

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Animal Wastes 127 TABLE 33 Mean Additional Mineral Composition of Animal Wastes Type of Sm Th U Yb Sb As Br F1 Al Cd Pb Resource (%) (%) (%) (%) (Jo) (%) (%) (%) (%) (%) (%) . Swine waste (processed) Cage layer waste (processed) Broiler litter Broiler litter (processed) 19.4 s4.4 1.0 12.1 2.2 18.7 35 .8s 3.0 6.2 were lower in steers when the diet consisted entirely of ensiled cattle waste. Addition of high-moisture corn increased the means for these pa rameters. Lucas et al. (1975) reported that dehydrated cattle waste had a dry- matter digestibility of 16.6 percent and that the metabolizable energy value was 0.485 Mcal/kg dry matter. Thorlacius (1976) reported a nutritional evaluation of dehydrated cattle waste using sheep. Diets containing 0, 50, or lOO percent waste were compared. During the final lO days of a digestibility trial, intake of dry matter was 2,632, 2,277, and 2,050 g for the three diets, respectively; dry-matter digestibility was 62.7, 51.7, and 26.7 percent, respectively; and nitrogen digestibility of the three diets was 70.9, 62.6, and 42.2 percent, respectively. Lipstein and Bornstein ~ 1971 ~ investigated the value of dried cattle waste for broiler chickens. It was concluded that the waste had little or no value as a source of energy or protein. Littlefield et al. (1973) found that cattle waste was of some value as a dietary source of yolk pigment for laying hens. Faruga et al. (1974) also reported the yolk color was improved with cattle waste in the diet of laying hens. With 0, 3, 6, and 9 percent dehydrated waste in the diet, feed intake per dozen eggs was 5.83, 5.49, 6.03, and 5.20 kg or 0.99, 0.94, 1.04, and 0.88 kg digestible crude protein/kg eggs, respectively. Metabolizable energy was 14.16, 13.66, 15.36, and 13.59 Mcal/kg eggs, respectively. The nutritional value for poultry of a protein fraction of cattle waste obtained by a commercial process (Cereco) was reported by Kienholz et al. (19751. Estimated me- tabolizable energy value (poultry) of the product was 2.3 Mcal/kg. Hennig et al. (1972) conducted a nutritional evaluation of dehydrated  swine waste using cattle and sheep. With sheep, digestibility of waste nitrogen in a pelleted diet was 57.4 percent. Cattle fed pellets containing 40 percent swine waste plus 1 kg hay daily ate on average 6.13 kg pellets

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Animal Wastes 129 daily and gained 1.1 kg daily. Flachowsky ~ 1975) fed mixtures of pelleted feed containing 30 or 50 percent swine waste to growing bulls. After a period of adjustment the diets were accepted readily and consumption of the test diets was 7.58 and 8.20 kg dry matter/head/day, respectively. Solids obtained from semiliquid swine waste were found to have a lower energy value than the waste itself, and the feeding value was estimated to be similar to that of medium quality hay. Flachowsky (1977) also reported on another experiment on the nutritional value of the undissolved fraction of swine waste. Intake was depressed when the waste represented 50 percent of the diet, which was attributed to the high iron content of the diet (2,002 mg/kg). Pearce (1975) found that the dry-matter digesti- bility of swine waste was about 29 percent when fed to steers or sheep at levels up to 45 percent of the diet as a replacement for hay. Kornegay et al. (1977) reported that the digestibility of the components of swine waste when fed to growing gilts were energy, 46.7 percent; dry matter, 48 percent; crude protein, 60.1 percent; crude fiber, 40.9 percent; ether extract, 54.1 percent; nitrogen-free extract, 45.9 percent; and ash, 31.6 percent. Jentsch et al. (1977) investigated the energy value of pelleted swine waste with young bulls and mature sheep. Digestibility was only slightly reduced when the level of waste in the diet was raised from 25 to 42 percent. Addition of waste to the diet increased the proportion of butyric acid in rumen fluid in both species. Olden and Dinius (1976) investigated the nutritive value for cattle of cage layer waste dehydrated and processed to recover compounds for industrial and medical use. Diets did not differ in digestibility of dry matter or acid detergent fiber when they contained O or 10.5 percent waste. Nitrogen retention was 30.1 percent with the waste diet, 34.1 percent with 3 percent uric acid in the diet, and 41.4 percent with 3.5 percent sodium urate in the diet. Rumen fluid pH was between 6.7 and 7.1 with all diets and was not affected by treatment. With up to 15 percent waste in the diet there was no significant difference in digestibility of dry matter, fiber energy, or nitrogen or in nitrogen retention. With dairy cows, Kristensen et al. (1976) reported that the digestibility of organic matter in dehydrated layer waste was 60 to 65 percent. Silva et al. (1976) conducted a digestibility trial with dairy cows fed diets containing up to 30 percent dehydrated layer waste. Digestibility of energy declined from 59.5 percent with the control to 54.8 percent with the diet containing 30 percent waste, and crude protein digestibility dropped from 59.2 to 53.1 percent. Digestibility of dry matter with the two diets was 58.5 and 39 percent, respectively. Including 10 percent waste in the diet had a slight effect on digestibility of dry matter and crude protein, and there was no marked reduction until the level of inclusion reached 20 percent.

1 30 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS Guedas (1966, 1967) reported on the digestibilities of diets containing O or 80 percent dehydrated layer waste with sheep. Mean digestibility of the waste diet was crude protein, 69.9 percent; crude fiber, 29.9 percent; and nitrogen-free extract, 71.4 percent. It was calculated that uric acid represented about 8 percent of the absorbed nitrogen. Parigi-Bini (1969) reported that the metabolizable energy value of dehydrated layer waste for sheep was 2.22 Mcal/kg. With O or 32 percent waste in the diet, apparent digestibilities were, respectively, dry matter, 87.5 and 80.5 per- cent; crude protein, 85.0 and 77.9 percent; crude fiber, 59.4 and 46.7 percent; ether extract, 85.7 and 78.7 percent; and nitrogen-free extract, 93.1 and 89.1 percent. Neither rumen pH nor the molar proportions of volatile fatty acids in rumen liquor were affected. Diets containing 0, 25, 50, 75, or 100 percent dehydrated layer waste were fed to sheep (Lowman and Knight, 1970~. Metabolizable energy value of the waste was estimated to be 1.74 Mcal/kg dry matter. Values calculated for the diets containing 100 percent waste and 100 percent barley were, respectively, dry matter, 56.6 and 77.9 percent; organic matter, 66.5 and 80.7 percent; energy, 60.3 and 80.0 percent; nitrogen, 77.2 and 68.4 percent; and copper, 24.2 and 51.0 percent. Tinnimit et al. (1972) fed diets in which dehydrated layer waste or soybean meal supplied 40 to 65 percent of total protein to sheep averaging 31 kg. When waste was increased in the diet from a level of 20 to 80 percent, dry-matter digestibility fell from 74 to 58 percent, and organic- matter digestibility fell from 77 to 68 percent. It was calculated that the digestible dry matter in dehydrated layer waste was about the same as that in low-quality alfalfa hay but that digestible organic matter was about 1.25 times greater. Bohme (1973) reported that with sheep the digestibility of organic matter in dehydrated layer waste was 67 percent. The digestible energy value of the waste was estimated to be 2.304 Mcal/kg dry matter and TDN value was estimated at 51 .4 percent. With 30 percent dehydrated layer waste in the diet, Hennig et al. (1975) reported that crude protein digestibility of the waste by sheep was 83 percent and that digestible crude protein content was 33 percent (dry-matter basis). Digestibility of dehy- drated layer waste for sheep was estimated by Salo et al. (1975) as follows: organic matter, 62.8 percent; crude protein, 76.9 percent; ether extract, 33.1 percent; crude fiber, 31.7 percent; and nitrogen-free extract, 57.5 percent. Metabolizable energy value was estimated to be 1.58 Mcal/kg. High values for digestibility of organic matter in sheep fed dehydrated layer waste were reported by Zgajnar (19754. The diets contained 0, 15, 25, or 35 percent waste. The effect of raising the level of waste in the diet was to lower the organic-matter digestibility of waste from 97.6 to 84 percent. Digestibility for crude protein increased from 68.6 to 77.9 percent and for nitrogen-free extract from 79.9 to 87.6 percent as the level

Animal Wastes 131 of waste was increased from 15 to 35 percent. Digestibility of crude fiber was 85.5 percent when the diet contained 25 percent waste, and it was lower with the other levels. Smith and Lindahl (1977) found that lambs digested the dietary nutrients equally well when the diet contained alfalfa or dehydrated layer waste, except that ash was 43 percent less digestible in waste diets. Swingle et al. (1977) found that the dry-matter intake of sheep was not affected when dehydrated poultry waste, cottonseed meal, or urea provided over 85 percent of total dietary nitrogen. About 35 percent of the absorbed nitrogen was retained with the diet containing cottonseed meal, whereas 16 percent was retained with the diet containing dehydrated layer waste or urea. Using dehydrated layer waste ensiled with corn forage, Goering and Smith ~ 1977) found that digestibility of dry matter by sheep was 63 percent; it was 64 percent with a control diet containing soybean meal. Organic- matter digestibility was the same at 65 percent. Daily organic matter consumed was 35 and 28 g/Wkg075, respectively. Smith and Calvert (1976) compared dehydrated broiler waste and soy- bean meal as nitrogen supplements for sheep. Digestibilities of dry matter, organic matter, and nitrogen were not significantly different at 65.4 and 65.2 percent, 66.4 and 65.4 percent, and 53.7 and 57.9 percent, respec- tively. Poultry litter waste was evaluated as a nutrient by several investigators. Bhattacharya and Fontenot (1965) found with sheep that the digestibility of crude protein in broiler litter was 64.8 to 67.1 percent. Apparent di- gestibilities of peanut hull and wood shaving broiler litter with sheep were: crude protein, 70.4 to 73.5 percent; crude fiber, 66.1 to 71.5 percent; ether extract, 56.3 to 62.7 percent; nitrogen-free extract, 68.6 to 74 per- cent; dry matter, 61.5 to 66.1 percent; and energy, 63.1 to 64.8 percent (Bhattacharya and Fontenot, 19661. Geri et al. (1970a,b,c) reported that the production of volatile fatty acids in vitro from litter waste was similar to that from common feedstuffs, with a tendency towards an increased proportion of propionic acid. Protein digestibility of the waste was esti- mated to be at least 87 percent. Cross et al. ~ 1978) found with beef steers that blood plasma urea nitrogen was about 50 percent higher with a diet containing 50 percent broiler litter silage than with a control diet, but that plasma and rumen fluid values were within normal physiological ranges. Muftic et al. (1968) fed a diet containing 80 percent poultry litter waste to dairy cows and reported that digestibilities were: dry matter, 60.3 percent; crude protein, 63.8 percent; true protein, 62 percent; nonprotein nitrogen, 71.4 percent; fiber, 26.6 percent; and nitrogen-free extract, 69.9 percent. Digestible crude protein of the litter was estimated to be 16.2 percent and starch equivalent was 35.8 percent.

132 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS Unprocessed wastes do not appear to have been evaluated as animal feeds, but investigations have been conducted on wastes with minimal processing. Flipot et al. (1975) reported on an evaluation of fresh poultry waste treated with 3 percent tannic acid or 2 percent paraformaldehyde and included in the diet of growing sheep at a level of 64 percent, wet- weight basis. Digestibility of dry matter and total nitrogen was 69.9 and 80.8 percent for a control diet based on soybean meal, 59.3 and 71.8 percent for the diet with tannic acid, and 54.8 and 71.5 percent for the diet with paraformaldehyde, respectively. Except for total nitrogen di- gestibility these differences were significant with the waste diets. Dry- matter intake was lower with the paraformaldehyde diet. Evans et al. (1978b) fed wet cage layer waste along with corn silage to yearling Suffolk ewes. The waste was offered unsupplemented or sup- plemented with 2 percent molasses or 1 percent propionate. The effect of supplementation was to increase intake of waste dry matter from about 18.5 to 19.5 g/Wkg0 7s/day with molasses and to about 23 g/Wkg0 75/day with propionate. On all treatments, intakes of total nitrogen and minerals were in excess of accepted requirements, indicating that the waste was a good source of these nutrients. Smith et al. (1978) investigated wet cage layer waste as a protein supplement for calves. It was concluded that plasma urea nitrogen levels indicated a relatively slow release of nitrogen from the waste, which the researchers considered made it an ideal source of nitrogen for rumen ~ . function. Performance of Animals Fed Animal Wastes Cattle Waste Anthony and Nix (1962) and Anthony (1966' established the feasibility of feeding steer waste to cattle. Anthony (1970) fed yearling beef animals a concentrate diet consisting of corn silage and ground ear corn supple- mented with urea, cottonseed meal, minerals, and vitamin A, or a diet consisting of 40 parts wet cattle waste and 60 parts air-dried concentrate. No effect on feed intake or gain was noted. Hsu (1976) reported on the performance of cattle feed silages containing O to 36 percent cattle waste. In one trial, daily gain was decreased by 50 percent as a result of the inclusion of waste in the diet. In the other trial, daily gain was 1.22 kg with the waste and 1.14 with the control diet. Newton et al. (1977) fed heifers a control diet of corn, Bermuda grass pellets, and urea, or a wastelage diet containing 40 percent wet fermented cattle waste. Control animals averaged 1.34 kg/day and required 5.02 kg drv matter/kg gain; wastelage animals averaged 1.27 kg/day and required

Animal Wastes 133 5.40 kg dry matter/kg gain. Harpster et al. (1978) investigated the growth of steers fed diets containing 40 to 75 percent ensiled cattle waste, the remainder of the ration being high-moisture corn. Daily gain and feed/ gain ratio for the control diet were 1.10 kg and 6.48. With 40, 50, and 75 percent waste in the diet these parameters were 1.05 kg and 7.88; 1.03 kg and 7.95; and 0.75 kg and 10.41, respectively. Lamm et al. (1979) found that dry-matter intake was similar for calves fed wastelage or was- telage treated with sodium hydroxide, but was lower than that of calves fed a corn silage control diet. Daily gain was similar with all diets. Richter et al. ~ 1980) investigated performance of cattle fed 0, 20, 40, or 60 percent cattle waste roughage obtained by a commercial process (Corral Industries Inc. ). Over a 124-day period daily gains were 1.10, 1.53, 1.58, and 1.51 kg, respectively. Schake et al. (1977) found that body weight maintenance was achieved in cows when 68.6 percent of the feed dry matter was high- fiber waste obtained from fresh cattle waste by use of a vibrating screen technique. Diaz and Elias (1976) reported on the use of cattle waste in swine feeding. Pigs averaging 30 kg were fed diets supplemented with torula yeast and containing 0, 25, or 50 percent ensiled cattle waste. Daily gain was 507, 419, and 375 g, respectively, and feed/gain ratio was 3.99, 4.65, and 5.57. Laying hens were fed a control diet or a diet containing 10 percent dehydrated cattle waste as the only source of animal protein (Saedi and Zohari, 19681. Egg production was 70 and 61.7 percent, respectively, and feed/dozen eggs was 3.70 and 4.12 kg. Swine Waste Flachowsky (1975, 1977) investigated the performance of cattle fed diets containing swine waste. Mixtures of pelleted feed containing 30 or 50 percent solid material from swine semiliquid waste were fed to cattle in a 252-day test. A control group was given pelleted feed with 36 percent straw. Daily gain for the control and groups fed 30 and 50 percent waste was 1.23, 1.18, and 1.00 kg, respectively. In another trial, bulls were grown for 315 days on pelleted diets containing 0, 25, or 50 percent swine slurry waste as a replacement for straw. Daily gain was 1.03, 1.04, and 0.84 kg, respectively, and intake of dry matter was 4.60, 3.23, and 3.47 kg/kg gain. Poultry Waste Performance data for cattle fed diets containing dehydrated layer waste (DLW) are summarized in Table 35 (Andersen et al., 1976; Batsman,

134 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS TABLE 35 Performance of Cattle Fed Diets Containing Dehydrated Layer Waste (DLW) Dietary Treatment Performance Control Waste Reference Daily gain (kg) 1.22 1.22 El-Sabban et al. (1970) 1.24 1.25 Meregalli et al. (1971) 1.42 1.47 Meregalli et al. (1973) 0.98 1.01 Pereira et al. (1972) 0.79 0.70 Tinnimit et al. (1972) 0.79 0.81 Batsman (1973) 1.20 1.22 Oliphant (1974) 0.81 0.91 Clark et al. (1975) 1.43 1.31 Andersen et al. (1976) 1.20 1.11 Cullison et al. (1976) 0.72 0.68 Lamm et al. (1976) 0.60 0.86 Oltjen and Dinius (1976) 1.62 1.29 Koenig et al. (1978) 0.98 0.93 Smith et al. (1979) 1.01 0.95 Vijchulata et al. (1980) Mean 1.07 1.05 Daily feed (kg DM) 10.27 10.02 El-Sabban et al. (1970) 2.56 2.50 Tinnimit et al. (1972) 5.77 5.75 Oliphant (1974) 7.80 8.70 Clark et al. (1975) 8.74 8.77 Cullison et al . (1976) 5.70 5.47 Lamm et al. (1976) 9.35 7.43 Koenig et al. (1978) 6.57 6.51 L. W. Smith et al. (1979) 7.95 7.99 Vijchulata et al. (1980) Mean 7.19 7.02 Feed/gain ratio 12.53 12.12 El-Sabban et al. (1970) 5.96 6.40 Meregalli et al. (1971) 5.78 5.61 Meregalli et al . (1973) 13.20 13.80 Pereira et al. (1972) 3.24 3.50 Tinnimit et al. (1972) 4.79 4.88 Oliphant (1974) 9 60 9.60 Clark et al. (1975) 3.77 3.78 Andersen et al. (1976)  7.28 7.90 Cullison et al. (1976) 7.94 8.00 Lamm et al. (1976) 14.18 10.32 Oltjen and Dinius (1976) 6.07 5.91 Koenig et al. (1978) 7.16 7.81 L. W. Smith et al. (1979) 7.85 8.45 Vijchulata et al. (1980) Mean 7.81 7.72

Animal Wastes 135 1973; Clark et al., 1975; Cullison et al., 1976; El-Sabban et al., 1970; Koenig et al., 1978; Lamm et al., 1976; Meregalli et al., 1971, 1973; Oliphant, 1974; Oltjen and Dinius, 1976; Pereira et al., 1972; Tinnimit et al., 1972; and Vijchulata et al., 19801. The means for waste-fed animals were obtained by averaging over all levels, though some of the levels (up to 50 percent of the dry matter) were probably excessive. Mean daily liveweight gain, daily feed dry-matter intake, and feed/gain ratio for an- imals fed control and waste diets were, respectively, 1.07 kg and 1.05, 7. l 9 kit and 7.02. and 7.81 kg and 7.72. These results indicate excellent performance with diets containing waste. , . · , , ~ ~e, ~ , ~ , The data obtained by Bucholtz et al. (1971) were not included with the above data because of the unusually low crude protein content ~ 17 percent) of the waste used and the anticipated poor performance obtained with a level of 32 percent waste in the diet. In addition these workers reported that the test animals selectively avoided the waste in the diet, with the result that the dry matter consumed had a low crude protein content. Generally, the inclusion of poultry waste did not affect feed intake ad- versely. However, Koenig et al. (1978) reported a reduction in intake from 9.35 to 7.43 kg dry matter daily when 10 percent of a formaldehyde- treated waste was fed. This was attributed to the waste diet's becoming stale quickly at the high environmental temperatures experienced. Such temperatures could also be expected to volatilize any residual formalde- hyde, with an adverse effect on intake. A waste used by Andersen et al. (1976) was Urimix, a commercial product available in Scandinavia, containing 90 percent dehydrated layer waste, 5 percent animal fat, and 5 percent molasses. Up to 45 percent was included in the diet of young bulls with no loss in performance until the content of Urimix in the diet exceeded 30 percent. The remainder of the diet was barley, oats, vitamins, and minerals, and in some cases soybean meal. Cullison et al. (1976) reported on the use of dehydrated broiler waste (DBW) in steer diets. Three diets based on corn were employed: control (soybean meal supplying the supplementary protein), half of the supple- mentary protein supplied by dehydrated broiler waste, and all of the sup- plementary protein supplied by DBW. Respective daily gains were 1.20, 1.18, and 1.11 kg; daily feed intake was 8.74, 8.89, and 8.77 kg; and feed/gain ratio was 7.28, 7.53, and 7.90. Milk-production data are summarized in Table 36 for dairy cows fed DEW at levels generally about 15 percent of the dietary dry matter (Bull and Reid, 1971; Kneale and Garstang, 1975; Kristensen et al., 1976; Silva et al., 1976; Smith et al., 1976; Thomas et al., 1972~. The means for waste-fed cows were obtained by averaging overall levels, though some

136 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS TABLE 36 Milk Production of Cows Fed Diets Containing Dehydrated Layer Waste (DLW) Dietary Treatment Performance Control Waste Reference Milk yield (kg/day) 21.2 17.8 Bull and Reid (1971) 19.6 20.6 Thomas et al. (1972) 14.8 15.2 Kneale and Garstang (1975) 20.0 19.8 Kristensen et al. (1976) 21.2 17.2 Silva et al. (1976) 17.1 15.4 Smith et al. (1976) Mean 19.0 17.7 Milk fat (%) 3.68 3.92 Bull and Reid (1971) 3.30 3.87 Thomas et al. (1972) 3.47 3.42 Kneale and Garstang (1975) 3.41 3.33 Silva et al. (1976) 3.70 3.60 Smith et al. (1976) Mean 3.51 3.63 Milk total solids (%) 12.40 12.56 Bull and Reid (1971) 11.80 11.85 Kneale and Garstang .(1975) 11.93 11.62 Silva et al. (1976) Mean 12.04 12.01 of the levels of waste fed were probably excessive. Mean daily milk yield with fat and total solids for cows fed control and waste diets were, re- spectively, 19 and 17.7 kg, 3.51 and 3.63 percent, and 12.04 and 12.01 percent. The overall trend was for daily milk yield to be reduced slightly, but the results are very encouraging since it is well known that milk production of dairy cows can easily be depressed by the use of inappro- priate diets. Mean fat content was slightly higher in waste-fed cows, possibly in response to the reduction in total milk yield. A waste product used by Kristensen et al. (1976) was Urimix similar to that used by Andersen et al. (19761. The highest level used was 40 percent of the concentrate portion of the diet, and in general, the differ- ences in milk production between cows fed that diet and a control diet were not significant. The beneficial effect on energy intake of including animal fat in the Urimix product probably explains why milk production

Animal Wastes 137 was not affected in the experiments conducted by Kristensen et al. (1976~? yet was lowered with the dehydrated layer waste at up to 32 percent in dairy concentrates in the experiments conducted by Kneale and Garstang 1975) and Smith et al. ~ 19761. Performance data for sheep fed diets containing dehydrated layer waste are summarized in Table 37 (Cuevas, 1969; Goering and Smith, 1977; Kazheka and Kozyr, 1975; Merwe et al., 1975; Smith and Calvert, 1976; Smith and Lindahl, 1977; Thomas et al., 1972; Tinnimit et al., 1972~. The means for waste-fed animals were obtained by averaging overall levels, though some of the levels (up to 50 percent of the dry matter) were probably excessive. Mean daily liveweight gain and feed/gain ratio for animals fed control and waste diets were, respectively, 0.19 and 0.18 kg, and 5.52 and 6.66. These results indicate excellent growth performance in growing sheep fed diets containing waste, though utilization of diets containing waste appears to be significantly lower than that of control diets. This may be a reflection of inadequate energy and/or excess ash for young growing lambs. TABLE 37 Performance of Sheep Fed Diets Containing Dehydrated Layer Waste (DLW) Dietary Treatment Performance Control Waste Daily gain (kg) 0.20 0.22 Cuevas (1969) 0.21 0.16 Thomas et al. (1972) 0.35 0.24 Tinnimit et al. (1972) 0.22 0.21 Berbeci et al. (1975) 0.18 0.17 Kazheka and Kozyr (1975) 0.20 0.12 Merwe et al. (1975) 0.05 0.13 Goering and Smith (1977) 0.19 0.18 Smith and Calvert (1976) 0.15 0.18 Smith and Lindahl (1977) Mean 0.19 0.18 Feed/gain ratio 7.14 11.11 Thomas et al. (1972) 4.16 4.52 Tinnimit et al. (1972) 4.50 3.41 Berbeci et al. (1975) 6.53 10.30 Merwe et al. (1975) 5.87 6.53 Smith and Calvert (1976) 4.94 4.08 Smith and Lindahl (1977) Mean 5.52 6.66

138 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS Pelleting of the feed appears to be beneficial in avoiding low intake. Smith and Calvert (1976) and Smith and Lindahl (1977) used complete pelleted diets and found that differences in performance criteria were not significant. Wet poultry wastes have been used in several trials. McNiven et al. (1976) mixed unprocessed layer waste containing 75 percent moisture in a diet diluted to 80 percent moisture for sheep. A control diet had either 10 or 80 percent moisture. With the two control and the waste diets, respectively, daily gain was 0.12, 0.14, and 0.13 kg, and intake of organic matter/kg gain was 6.93, 5.34, and 6.03 kg. Smith et al. (1978) included 0 or 22 percent fresh waste from caged layers in the diet of bull calves. The diet was based on corn silage and high-moisture corn, and was sup- plemented with soybean meal or waste. Daily gain was 1.29 and 1.03 kg, respectively, and daily dry-matter intake was 4.15 and 3.86 kg. In a subsequent investigation fresh cage layer waste was treated with a 0.5 percent wet weight acetic-propionic acid mixture, stockpiled and mixed at a 68 percent level (wet basis) into corn silage just prior to feeding. The diet was fed to growing/finishing Hereford steers, in comparison with diets based on soybean meal or urea. Daily gain, feed efficiency, and carcass and empty body gains were similar with all treatments. It was concluded that up to 22 percent waste (DM basis) was readily accepted by cattle. Only a few experiments on feeding dehydrated layer waste have in- volved swine, and performance data are summarized in Table 38 (Denisov et al., 1974, 1975b; Geri, 1968; Osterc, 19721. The means for waste-fed TABLE 38 Performance of Swine Fed Diets Containing Dehydrated Layer Waste (DLW) Dietary Treatment Performance Control Waste Reference Daily gain (kg) 0.55 0.49 Geri (1968) 0.65 0.5 1 Osterc ( 1972) 0.61 0.52 Denisov et al. (1974) 0.59 0.55 Denisov et al. (1975b) Mean 0.60 0.52 Feed/gain ratio 3.66 3.99 Geri (1968) 4.58 5.64 Denisov et al. (1974) Mean 4. 12 4.82

Animal Wastes 139 animals were obtained by averaging overall levels. Mean daily liveweight gain and feed/gain ratio for animals fed control and waste diets were, respectively, 0.60 and 0.52 kg, and 4.12 and 4.82 kg. These results are encouraging since levels of up to 35 percent waste were used and since the pig does not have a digestive system capable of utilizing crude fiber or nonprotein nitrogen efficiently. One interesting aspect of the experiments conducted by Geri (1968) is that the swine given dehydrated layer waste received no supplements of antibiotic or vitamin By. Also, the initial weights of the pigs involved were as low as 17 kg in some groups. Performance data for growing chickens fed diets containing dehydrated layer waste are summarized in Table 39 (Biely and Stapleton, 1976; Biely et al., 1972; Flegal and Zindel, 1971; Fookes, 1972; Lee and Blair, 1973; Lee and Yang, 1975; Stapleton and Biely, 1975~. The means for waste- fed chickens were obtained by averaging overall levels, although some of the levels (up to 30 percent) were excessive. Mean daily liveweight gain and feed/gain ratio for chickens fed control and waste diets were, re- spectively, 16.1 and 15.7 g, and 2.36 and 2.60 g. These results indicate that growth can be maintained with diets containing waste, but that feed efficiency is depressed. This can be attributed mainly to the low meta- bolizable energy value of the waste. Flegal and Zindel (1971) reported that growth and feed/growth ratio with diets containing waste could be improved by the addition of fat to the diet. Bhargava and O'Neil (1975) investigated the growth performance of broiler chickens fed diets containing up to 20 percent dried waste from caged broilers. Mean daily liveweight gain and feed/gain ratio for the control and waste-fed broilers were, respectively, 23.6 and 23.0 g, and 2.28 and 2.33 g. All levels above 5 percent waste reduced gain and feed efficiency significantly, but levels up to 20 percent had no significant effect on growth when the diets were equalized for energy and protein. The data of Trakulchang and Balloun (1975a,b) were not included in the above summary since the waste used was an air-dried product with a very low level of crude protein (21 percent). They found that the inclusion of broiler waste in the diet of growing chickens at a level of 10 or 20 percent resulted in a progressive decrease in growth rate and feed-conversion efficiency. Performance data for laying chickens fed diets containing dehydrated layer waste are summarized in Table 40 (Flegal and Zindel, 1971; Hod- getts, 1971; Lee and Bolton, 1977; Lee and Yang, 1976; Vogt, 1973~. The means for waste-fed birds were obtained by averaging overall levels, though some of the levels used (up to 40 percent) were excessive. Mean

140 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS TABLE 39 Performance of Growing Chickens Fed Diets Containing Dehydrated Layer Waste (DLW) Dietary Treatment Performance Control Waste Reference Daily gain (g) 15.6 15.4 Flegal and Zindel (1971) 16.9 15.8 Biely et al. (1972) 7.7 7.7 Fookes (1972) 29.3 30.3 Lee and Blair (1973) 24.6 24.5 Lee and Yang (1975) 10.1 8.8 Stapleton and Biely (1975) 8.7 7.7 Biely and Stapleton (1976) Mean 16.1 15.7 Feed/gain ratio 2.11 2.25 Flegal and Zindel (1971) 2.43 2.81 Biely et al. (1972) 2.87 3.23 Fookes (1972) 2.50 2.42 Lee and Blair (1973) 2.61 2.92 Lee and Yang (1975) 2.05 2.29 Stapleton and Biely (1975) 1.98 2.28 Biely and Stapleton (1976) Mean 2.36 2.60 egg production and feed/dozen eggs for the control and waste-fed birds were, respectively, 71.9 percent and 72.8 kg, and 1.90 percent and 1.90 kg. Flegal and Zindel (1971) reported that the inclusion of up to 20 percent waste did not influence egg production or feed efficiency, and that the inclusion of up to 40 percent did not adversely affect egg weight or shell thickness. Vogt (1973) concluded that 10 percent waste was unsuitable for inclusion in layer feed unless the energy content of the feed was raised. Lee et al. (1976) raised replacement layers on diets containing up to 5 percent dehydrated layer waste. No effects on weight at 18 weeks were noted, but feed consumption and feed efficiency were better with the control diet. Subsequent laying performance was not affected. Poultry Litter Performance data for cattle fed diets containing poultry litter are sum- marized in Table 41 (Batsman, 1973; Borgioli and Tocchini, 1969; Bos- man, 1973; Boubedja and Marx, 1974; Cross and Jenny, 1976; Cross et al., 1978; Cullison et al., 1976; Denis-ov et al., 1973; Fontenot et al.,

Animal Wastes 141 TABLE 40 Performance of Laying Hens Fed Diets Containing Dehydrated Layer Waste (DLW) Dietary Treatment Performance Control Waste Reference Egg production 64.7 61.1 Flegal and Zindel (1971) 78.9 79.6 Hodgetts (1971) 82.3 86.9 Vogt (1973) 73.8 72.4 Lee and Yang (1976) 59.6 64.0 Lee and Bolton (1977) Mean 71.9 72.8 Kg feed/dozen eggs 1.95 2.17 Flegal and Zindel (1971) 2.00 1.86 Hodgetts (1971) 1.63 1.51 Vogt (1973) 1.64 1.66 Lee and Yang (1976) 2.29 2.30 Lee and Bolton (1977) Mean 1.90 1.90 1966, 1971a; Kanev et al., 1971; Meregalli et al., 1973; Noland et al., 1955; Sommer and Pelech, 1971; Szelenyi et al., 1971; Velloso et al., 19701. The means for litter-fed animals were obtained by averaging over- all levels, though some of the levels used (up to 60 percent) were probably excessive. Mean daily gain and feed/gain ratio for control and litter-fed animals were 1.00 and 0.87 kg, and 10.18 and 11.58 kg, respectively. No significantly depressing effects on bull performance as a result of including up to 50 percent poultry litter were reported by Kanev et al. ~ 19711. Daily gain and feed/gain ratio with the control and test diets were, respectively, 1.12 kg and 5.49 feed units/kg gain, and 1.11 kg and 6.76 feed units/kg gain. Szelenyi et al. (1971) reported that cattle fed for 3 months on a standard grain mixture gained 1.25 kg daily, but that daily gain fell to 0.93 kg when 25 percent of the mixture was replaced by poultry litter. In a second trial the cattle gained 1.22 kg daily with a mixture containing 25 percent litter and adjusted levels of bran and peanut meal. Levels of 33 and 50 percent of the diet (dry-matter basis) were used successfully with Simmental bulls (Batsman, 19731. Daily gain with a control and with the two test diets was 0.87, and 0.90 and 0.87 kg, respectively. In a subsequent trial, bulls 7 months of age were fed a control diet or diets containing 20, 40, or 60 percent litter. Daily gain was 0.71, 0.75, 0.71, and 0.72 kg, respectively. No significant effects on carcass

142 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS TABLE 41 Performance of Cattle Fed Diets Containing Poultry Litter Dietary Treatment Performance Control Waste Reference Daily gain (kg) 0.92 0.77 Noland et al. (1955) 0.73 0.52 Fontenot et al. (1966) 1.32 1.24 Borgioli and Tocchini (1969) 0.90 0.77 Velloso et al. (1970) 0.73 0.52 Fontenot et al. (1971 a) 1.12 1.11 Kanev et al. (1971) 1.14 0.94 Sommer and Pelech (1971) 1.25 1.07 Szelenyi et al. (1971) 0.79 0.79 Batsman (1973) 1.61 1.01 Bosman (1973) 0.90 0.81 Denisov et al. (1973) 1.32 1.23 Meregalli et al . (1973) 0.96 0.70 Boubedja and Marx (1974) 0.42 0.51 Cross and Jenny (1976) 1.17 1.12 Cullison et al. (1976) 0.72 0.83 Cross et al. (1978) Mean 1.00 0.87 Feed/gain ratio 13.16 17.38 Noland et al. (1955) 13.10 15.60 Fontenot et al . (1966) 13.10 16.40 Fontenot et al. (1971 a) 5.49 6.76 Kanev et al. (1971) 6.48 7.30 Bosman (1973) 9.30 9.37 Denisov et al. (1973) 12.50 14.50 Cross and Jenny (1976) 7.18 7.73 Cullison et al. (1976) 11.30 9.20 Cross et al. (1978) Mean 10.18 11.58 quality were noted. The litter used by Batsman had been dehydrated at 800°C. Denisov et al. (1973) used up to 40 percent litter waste with growing cattle and reported a resultant depression in daily gain from 0.89 to 0.6 kg, and intake of organic matter/kg gain rose from 9.1 to 12.3 kg. In a subsequent trial the cattle were fed diets containing 0, 15, 25, or 35 percent layer waste. Daily gains were 0.91, 1.02, 1.03, and 0.94 kg and intakes of organic matter/kg gain were 9.5, 8.2, 8.2, and 8.9 kg, respectively. Carcass yield was reported to be higher for the groups given 15 or 25 percent waste.  Meregalli et al. (1973) used ensiled litter with corn forage containing 7.0 percent crude protein, dry-matter basis. Daily gain with and without

Animal Wastes 143 litter in the silage was 1.32 and 1.23 kg, respectively. Other work on the use of silages containing litter was reported by Creger et al. (1973), Cross and Jenny ~ 1976), Cross et al. ~ 1978), McClure et al. ~ 1979), and Fontenot et al. ~ 1971 a). The results suggest that higher levels of litter can be utilized in ruminant diets by means of ensiling than by incorporating dehydrated waste into mixed diets. Fontenot et al. ~ 1971a) reported only an 8 percent drop in daily gain with 25 percent litter in a steer diet, yet Szelenyi et al. (1971) reported a 26 percent drop in gain when 25 percent of a feed mixture was replaced with nonensiled poultry litter. Cross and Jenny (1976) reported no depression in the gain of dairy heifers fed high-corn silage diets containing 0, 15, 30, or 45 percent turkey litter silage, and gain was improved significantly from 0.42 to 0.58 kg/day by the inclusion of 15 percent litter silage in the diet. Although gains were not affected by the level of litter silage in the diet, feed/gain ratio increased from 12.5 at the 0 percent level to 16.7 at the 45 percent level. The results of Cross et al. ~ 1978) tend to confirm their earlier findings (Cross and Jenny, 19761. Steers were fed 30 percent concentrate and 70 percent corn silage, or diets with 0, 10, 30, or 50 percent of the corn silage replaced with broiler litter silage. Daily gain was 0.72, 0.90, 0.94, and 0.63 kg, indicating a sig- nificant increase due to the inclusion of litter silage at up to 30 percent and a drop in performance only above that level. Feed/gain ratio showed the same trend and was, respectively, 11.3, 9.9, 9.7 and 10.6. At the 30 percent level, it was estimated that feed costs/kg gain were reduced by 23 percent. Processed poultry litter has been used in dairy diets. Muftic et al. ~ 1968) reported on the use of broiler litter dried at 60° to 70°C and fed to culled dairy cows in a mixture of 79 percent litter, 20 percent corn, and 1 percent minerals. During 4 months the diet was sufficient for maintaining or increasing body weight of the cows and for maintaining a milk yield of 4 to 6 liters/day. In a later study the same workers found that a similar mixture supplied the requirements for maintenance plus 10 to 20 liters of milk (Muftic et al., 19681. A large experiment by the same group (Muftic et al., 1974) involved two groups of 40 Black Pied cows over 2 years. The experimental group was fed a mixture of 77 percent broiler litter, 20 percent corn, and 3 percent vitamins and minerals, given at the rate of 12 leg daily along with 2 kg hay. Average milk yield with the control and waste diets was 10 and 10.4 kg/day, respectively, and butterfat content of the milk was 4.4 and 3.78 percent. Mean birthweight of calves was heavier with the waste diet, 37.8 versus 36.3 kg. It was reported that there was a higher incidence of reproductive disorders, such as retained placenta, related to the waste diet, possibly because the diet had not been adjusted correctly to ensure fertility. Mello et al. (1973) fed Brown Swiss

144 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS crossed with Zebu cows on diets containing up to 36 percent poultry litter for 77 days, along with corn meal, corncob meal, and soybean silage. Milk yield or composition was not affected by diet. All diets were well accepted by the cows, although there was some weight loss, which was attributed to the poor quality of the soybean silage. Galmez et al. (1971a,b) investigated the use of poultry litter in the diet of growing and breeding sheep. Lambs weighing about 28 kg initially were fed for 60 days on diets containing up to 68 percent broiler litter. Daily gain was better with the waste than with alfalfa hay alone. Ewes were fed a control diet or a diet with 63 percent broiler litter for 36 days before and 90 days after lambing. Mean birthweights of single lambs were 4.39 and 4.78 kg and their mean daily gain for 90 days was 146 and 171 g, respectively; the difference was not significant. Perez-Aleman et al. (1971) reported on the use of dried poultry waste (sterilized broiler litter) in growing swine diets. Levels of 0, 9, 17, or 23 percent were used. Daily gains were 576, 549, 426, and 513 g, and feed/ gain ratios were 3.48, 3.72, 4.07, and 4.20, respectively. There was no measurable effect on feed intake. Blair and Herron (1982) investigated the effects of including 10 percent dehydrated broiler litter in broiler diets. Liveweights at 8 weeks for the control and waste diets were 1,966 and 2,100 g, and feed/gain ratios were 2.14 and 2.13, respectively. Miscellaneous Flachowsky and Lohnert (1974) fed adult Merino wethers a control diet or a diet containing 44 percent dried rabbit waste. Intake was not affected, but only the protein was well digested (78 percent). Cereco protein produced by a patented process was fed at a level of 14 percent in a pelleted diet to rainbow trout (Post and Ward, 19751. No significant difference in gain was noted between the test group and a control group over a 20-week period. Ochoa et al. (1972) reported on the performance of sheep fed diets containing 0, 10, 20, or 40 percent of a waste mixture (equal proportions of poultry and swine waste). Daily gain was 178, 179, 187, 205, and 175 g, respectively. PROCESSING Among the procedures that have been used to process animal wastes prior to feeding are ensiling, dehydration, pelleting, preparation for liquid feed- ing, oxidation-ditch aerobic processing, commercial (patented) systems, and the use of wastes as substrates for single-cell protein production.

Animal Wastes 145 Ensiling Ensiling is a controlled anaerobic fermentation process during which car- bohydrates in the mixture are converted to lactic and other acids. Once sufficient acids are produced, bacterial action ceases and the ensilage is then stable. Heat is generated during the process, and an internal tem- perature of at least 25°C is usually achieved. Processing wastes by ensiling is economical; it has the further advantage that the process diminishes the hn~nrr1~ from ~.~.rtain notentialiv pathogenic organisms and renders the 44~^~ - rid -J rib o waste mixture more palatable. Feasibility of mixing cattle waste with grass hay and ensiling the mix- ture was explored by Anthony (19714. The mixture consisted of 57 parts waste and 43 Darts crass hay, and the ensiled mixture was termed wast ~v~~ r~~~~ =- elage. It appears that the addition of animal waste to corn forage before ensiling leads to an improvement in nutritive value. Harmon et al. (1975a) found that the addition of broiler litter to corn forage at 15, 30, or 45 percent of dry matter increased the crude protein content of the silage up to about 18 percent, dry-matter basis. Addition of waste increased final pH values and concentrations of lactic and acetic acids. Dry-matter content of silage was also increased when waste was included at the higher levels. Residues from medicinal drugs and mineral supplements are probably affected differently by ensiling. Caswell et al. ( 1978) found that amprolium was present at 10 mg/kg in broiler litter and was unaffected by fermen- tation. Zinc bacitracin was present at 0.78 units/g in broiler litter and was largely removed by fermentation. Although the broilers had been fed both ethopabate and monensin sodium, no detectable levels were found in the litter either before or after ensiling. Arsenic was present at 6.2 mg/kg in the litter and was not affected by ensiling. Dehydration Until the recent escalation in energy costs, dehydration was an attractive processing system. The high temperatures in dehydrators (370° to 700°C) reduced pathogens to low levels and frequently eliminated them entirely. In addition the odor was much reduced or removed. A typical waste dehydrator has been described by Surbrook et al. (1971~. Because path- ogens are killed in commercial dehydrators, dried poultry waste was the first animal waste product to be accepted by the American Association of Feed Control Officials. Air- or sun-dried waste has been investigated by some workers. This product is more likely to harbor viable organisms because of the relatively low temperatures employed in drying.

146 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS One disadvantage of dehydration is that a considerable loss of nitrogen and of other nutrients can occur with dry heat. For instance, Shannon and Brown ~ 1969) reported a 10.6 percent loss in nitrogen at 120°C. Caldertone and Wilson (1976) reported a 20.8 percent loss of nitrogen and a 5.9 percent loss of phosphorus on heating to dryness at 45°C. Silva et al. (1976) reported a 50 percent loss of organic components during drying. Smith and Calvert (1976) reported a 20 percent loss of nitrogen on drying broiler waste. Harmon et al. ~ 1974) have shown that the loss can be reduced by acidification prior to heating. The dehydrated material does not appear to undergo further change on storage for lengthy periods (Chang et al., 19741. This is in contrast to the fresh material as voided: For instance, Feldhofer et al. (1975) reported that crude protein dropped from 34 to 20 percent of dry matter on storage for 21 days. This work indicates that waste as voided (75 percent moisture content in the case of caged layers) should be dehydrated quickly after collection. At present the main disadvantage of dehydration is the high energy cost. Reduction of moisture content from 75 to 15 percent requires removal of 2,825 kg water/ton dry solids. Additional energy is required to operate the afterburner, found necessary to eliminate odors from flue gases. Esmay et al. (1975) reported that an oil-fired dehydrator and afterburner required 2,220 to 2,770 kcal (9.3 to 11.6 million J) of energy to remove l kg water. This indicates a thermal efficiency of 20 to 25 percent. Muller ~ 1976) estimated the cost of dehydrating at $25-$50 per ton of dehydrated material. Shannon et al. (1973) conducted a bacteriological survey on eight sam- ples of commercial dehydrated poultry waste used for animal feeding. The samples were not sterile and the organisms found were anthracoid bacilli, paracolon bacilli, Staphylococci, and E. colt. When voided, layer waste contains about 75 percent water (and gen- erally more if excessive water spillage occurs). An obvious solution to the reduction in dehydration costs is to predry the material before dehy- dration. Bressler and Bergman ~ 1971 ~ developed a two-stage drying system using mechanical stirring of the waste in the storage pits and high-velocity fans to remove up to 83 percent of the moisture before the waste was put into the dryer. Ostrander (1975) described a high-rise layer battery design in which waste is allowed to build up in the form of cones on slats under flat-deck cages. A design involving a drying tunnel in the barn was de- scribed by Sheppard et al. (19751. Waste predryed in this way may contain 14 to 40 percent moisture (Blair and Herron, 1982; Ostrander, 1975) and would be much less costly to dehydrate. It can be concluded that dehydration results in a product that can be used successfully in livestock feeding, but the process may not be eco- nomically feasible due to high energy costs.

Animal Wastes 147 Other Processes Pelleting Pelleting animal wastes prior to feeding was investigated by Hull and Dobie (1973), Smith and Lindahl (1977), and Smith et al. (19761. This system has the advantage that ingredient-sorting by animals is prevented; in addition the heat of pelleting is probably beneficial. However, a dis- advantage is that the waste has to be dried or dehydrated before it will pellet successfully. Liquid Feeding A liquid feeding system for layer waste was investigated for ruminants by Evans et al. ~ 1978a,b) and Smith et al. (19781. The addition of 2 percent molasses or l percent propionate was found to increase feed intake when the waste was fed along with corn silage. Intakes of nitrogen and minerals were sufficiently high with this system, suggesting that it merits further attention. One probable disadvantage of this type of system is its potential for transmitting disease. Smith et al. (1978) reported that 38 percent of the samples of waste were positive for salmonellae. Oxidation Ditch Aerobic digestion of swine waste using an oxidation ditch has been de- scribed by Day and Harmon (1974) to produce a nutrient-rich drinking water. As a result of single-cell protein production in the waste liquor during the digestion process, the protein content of the diet fed to swine could be reduced by 15 percent. This system should be directed toward nonruminants because they cannot utilize the nonprotein nitrogen present in the waste unless converted into protein through the mediation of mi- croorganisms. Several potential health problems exist with this system. Buildup of intestinal worm eggs has been noted, and there can be an increase in nitrate concentration in the ditch liquor. The survival time of Salmonella typhimurium in a model oxidation ditch was 17 days at summer temperatures and 47 days at winter temperatures (Will et al., 19731. Patented Systems Several commercial (patented) systems have been developed for process- ing animal wastes for feeding. Techniques involved include ensiling and fractionation (Cereco process) and chemical treatment (Grazon and Corral systems).

148 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS Substrates for Protein Production The use of wastes as substrates for protein production has been described by Calvert (19761. Among the organisms grown on these substrates were algae, yeasts, fungi, bacteria, house-fly larvae, and earthworms. Accord- ing to Calvert (1979), none of the systems involving algae, yeasts, bac- teria, fungi, insects, or earthworms contribute greatly to the supply of protein supplements for livestock feeds. Algal systems have been tested more adequately and appear to yield the most promising results. In the algal systems the amount of nitrogen converted to protein is as great or greater than that of any of the other systems, and the protein quality is high. Systems using yeasts, bacteria, and fungi all appear to show promise, but little published data critically evaluating the systems are available. Yields of protein were low when insects and earthworms were grown on waste as a substrate. These systems probably require a greater degree of technology than other systems, which may preclude their adoption as on- farm systems. UTILIZATION SYSTEMS Experimental A number of systems involving algae, yeasts, bacteria, fungi, insects, and earthworms for the conversion of animal wastes were reviewed recently by Calvert (19791. It was concluded that the algal systems had produced the most promising results. The algal system developed by Dugan et al. (1969, 1971) has the advantage that methane is produced during the pro- cess. In addition, it is claimed that after algal separation the water can be recycled. Potential algal yield in this system was estimated at 11 to 15 tons dry matter/ha/year. The system developed by Miner et al. (1975), which uses swine waste, was projected to yield 121.5 tons dry matter/ha/ year. Work is required to determine adequately the nutritional value of algae (Chlorella), but results to date suggest that algal protein may be comparable with protein from some conventional sources. The commercial feasibility of growing feed yeasts on hydrocarbon sub- strates suggests that work needs to be carried out on the use of animal wastes as substrates for yeast growth. Little work appears to have been done in this area (Calvert, 19794. In some systems bacterial cultures are used to digest animal wastes, and the digested material is of potential value as feed. The processed solid material has been fed successfully to cattle (Vetter, 1972) and to swine (Harmon et al., 1972) but problems appear to exist with the liquid (oxi

Animal Wastes 149 cation-ditch mixed liquor). Johnson et al. (1977) supplied this liquor as drinking water to laying hens and reported a rapid drop in egg production from 64.7 to 1 percent. The loss was attributed to increases in the levels of dissolved oxygen and nitrate from 4.7 to 6 and 210 to 1,300 mg/kg, respectively, suggesting that monitoring of these and perhaps other con- stituents would be necessary. Umstadter (1980) described a unique system for the treatment and uti- lization of cattle waste. Lagoons were used to purify the liquid waste and promote algal growth. Subsequently, Tilapia fish were introduced to utilize the algae (the fish could then be harvested). The sludge remaining after methane production was stated to be acceptable by cattle as feed, which could possibly replace 50 percent of the protein supplement in the diet. Experimental systems involving the treatment of animal wastes for liquid feeding have been investigated by Evans et al. (1978b) and Smith et al. (19781. Other systems have involved ensiling alone or with other feeds. For instance, Harmon et al. (1975b) found that the nutritive value of corn silage was improved by the addition of broiler litter. Acceptability of waste was also improved by ensiling. Anthony ~ 1969) reported satisfactory results from feeding ensiled cattle waste and grass hay. Saylor and Long (1974) showed that a satisfactory silage could be made from 60 percent poultry waste and 40 percent grass hay. Industrial Successful industrial systems involving dehydration, ensiling, liquid-solid separation, and chemical treatment have been developed. Dehydration involves passing the raw waste through a heat chamber which removes volatile material and exhausts it with the flue gases. As a result, an afterburner is now generally added to most dehydrators. A wide variety of dehydrators are in use commercially, and considerable use, especially, is made of dehydrated poultry waste in animal feeding. Ensiling is used extensively for feeding wastes to livestock and has the advantage that it is an on-farm system. A further advantage is that it is inexpensive. One disadvantage is that it may be seasonal in use. Various liquid-solid separation systems are being used to process wastes (Ward et al., 1975~. These systems have the advantage that they are mechanized and that the processed fractions have good animal accepta- bility. However, they are presently justified only in large feeding oper- ations. Chemical treatment of poultry wastes for incorporation into cattle diets is being practiced in the southern United States (Masters, 1977~. Advan

150 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS sages of this system are that no storage is required and that the treated waste can be used directly after treatment. Potential Utilization Animal wastes represent a very large but almost untapped resource for use as animal feed. Methods of utilizing this resource will vary, and they depend on a variety of factors. For example, minimum processing will be needed for poultry litter or cattle waste from the dry areas of the country, but considerable processing will be required for materials such as cattle waste from the humid east, swine waste, and caged layer waste. Because of their relatively low energy and their high level of nonprotein nitrogen, some of these wastes are best suited for use as feed for ruminants. Such high protein wastes as those from poultry production would be best suited for use in limited quantities as protein and mineral supplements. None of the wastes is high in available energy. The low-protein wastes will likely be used in substantial quantities in low-producing animals or in limited amounts in high producers. A variety of technically feasible processing methods is available. Un- fortunately, not all of these are economically feasible. Some of the more important processing methods are dehydration, ensiling, solid-liquid sep- aration, chemical treatment, and autoclave. It is likely that the methods that have a low requirement for fossil fuel will be the methods of choice. The most feasible processing method appears to be ensiling, alone or in combination with other ingredients. Combining high-moisture waste with low-moisture ingredients and low-moisture waste with high-moisture in ,_',, ,.__ --~ - ''ED - - gredients offers the most potential for high-quality silage. For example, caged waste could be ensiled with crop residues, and broiler litter with wastes from fruit or vegetable processing. The value of animal wastes will depend on their nutritional value and the price of other feeds. The wastes have been shown to be quite valuable when compared with other feedstuffs (Smith and Wheeler, 19791. It is also likely that the animal wastes will be used for production of fossil fuels, such as methane, ethanol, and fatty acids, and the residue used as feedstuffs. In fact, these energy-generating processes probably will not be economically feasible unless considerable value is recovered in the residue as a feedstuff. ANIMAL AND HUMAN HEALTH Human and animal health aspects of feeding livestock wastes have been reviewed by Fontenot and Webb (1975) and McCaskey and Anthony (19794.

Animal Wastes 151 Pathogenic Organisms There is no doubt that raw animal waste may contain pathogenic organ- isms. However, adequate processing renders the waste free of pathogens or with a much reduced profile of organisms capable of causing disease. One documented disease outbreak has apparently been linked to the feeding of animal waste, and it was attributed to faulty processing. Egyed et al. (1978a,b) described a disease outbreak in over 1,000 cattle and sheep in Israel, involving 25 farms in which feed containing 10 percent poultry litter was used. A diagnosis of botulism was suggested (Cohen and Ta- marin, 1978), although the toxin and organism could only be isolated from one animal. The botulism organism (Type D) appears to be endemic to Israel, since outbreaks have occurred in animals fed other feeds (Fon- tenot and Jurubescu, 19801. Total bacterial colonies were significantly increased in the silages containing 45 percent waste, but coliforms were not significantly different nor significantly lower in litter silage than in unsupplemented forage silage. No disease problems have been reported with poultry wastes in practical diets for beef cattle, dairy cattle, or sheep (Bucholtz et al., 1971; Bull and Reid, 1971; Drake et al., 1965; El-Sabban et al., 1970; Fontenot et al., 1966; Johnson et al., 1975; Liebholz, 1969; Noland et al., 1955; Southwell et al., 19584. Even calves, which are well known to be sus- ceptible to digestive upsets, remained healthy when fed diets containing wet cage layer waste (Smith et al., 19784. Feedlot cattle also remained healthy when fed diets containing cage layer waste treated with organic acids (O. B. Smith et al., 1979), and the researchers concluded that po- tential health problems were no more serious than with conventional feeds. Similarly, no disease problems were encountered when cattle waste was fed to cattle and poultry (Anthony, 1966, 1971; Durham et al., 1966), cage layer waste to layers (Flegal and Zindel, 1971), or swine waste to swine (Harmon, 19741. Nevertheless, animal wastes commonly contain pathogenic organisms (Alexander et al., 1968; Caldertone and Wilson, 1976; Carriere et al., 1968; Caswell et al., 1978; Knight et al., 1977; Kraft et al., 1969; O. B. Smith et al., 1978, 1979) and should be processed before being fed. Alexander et al. (1968) examined 44 field samples of poultry litter and found that 13 were negative for pathogenic bacteria. The other samples tested positive for 10 different species of Clostridium; 2 of Cornebacte- rium; 3 types of Salmonella; and various actinobacilli, Mycobacteria, Enterobacteriaceae, Bacilli, Staphylococci, Streptococci, and yeasts (Ta- ble 42~. Three Clostridia were regarded as pathogenic types (C. chauvoei, novyi, and perfringens) but were not harmful when injected intramuscu- larly into guinea pigs. Many of the organisms found were regarded as

152 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS TABLE 42 Results of Bacteriological Analysis of 44 Samples of Poultry Litter Types Isolated Number Isolated Clostridium perfringens Clostridium chauvoei Clostridium novyi Clostridium sordellii Clostridium butyricum Clostridium cochlearium Clostridium multiform en tans Clostridium carnis Clostridium tetanomorphum Clostridium histolyticum Corynebacterium pyogenes Corynebacterium equi Salmonella blockley Salmonella saint-paul Salmonella typhimurium var. Copenhagen Actinobacillus spp. Yeast Mycobacterium spp. Enterobacter~aceae (other than Salmonellae) Bacillus spp. Staphylococcus spp. Streptococcus spp. 2 All samples All samples All samples All samples SOURCE: Alexander et al. (1968). normal inhabitants of the intestinal tract of animals. Litter that was negative for Salmonella choleraesuis was inoculated with this serotype and re- mained contaminated for 29 days. Carriere et al. (1968) reported finding mycobacteria in 8 out of 29 samples of poultry litter. They concluded that  cattle fed poultry litter might be infected or sensitized to Mycobacterium avium and/or atypical types of mycobacteria, leading to false positive reactions and incorrect diagnosis of tuberculosis. Kraft et al. (1969) tested composite samples of freshly voided excrete from 91 poultry houses and found that 29 percent were positive for salmonellae. The houses were located on 36 farms, 18 of which yielded one or more positive samples. Smith et al. (1978) found that the rate of Salmonellae contamination in fresh layer waste was 38 percent. Diets containing waste were also found to be contaminated. Fungi also may be present in animal and poultry wastes (Lovett, 1972; Lovett et al., 1971; Singh, 19741. However, they have been isolated from

Animal Wastes 153 poultry feeds also (Lovett, 1972; Singh, 19741. The types found in litter by Lovett ~ 1972) and Lovett et al. ~ 1971 ~ were Penicillium, Scopulariop- sis, and Candida, mainly, and in feeds were mainly Penicillium, Asper- gillus, Fusarium, and Mucor. The data indicate that processing has a marked pasteurizing effect. Harmon et al. ~ 1975a) harvested corn forage at 30 or 40 percent dry matter and ensiled it with litter from broilers kept on wood shavings to supply 15, 30, or 45 percent of the dry matter. Total bacterial counts/g were significantly increased in the silages containing 45 percent waste, but coliforms were not significantly increased or were significantly decreased in the litter silages, compared with the control silage. McCaskey and Anthony (1975) investigated the survival of organisms in a mixture of 45 parts ground shelled corn, 15 parts corn silage, and 40 parts cattle waste, which was blended and then ensiled. A total of 27 salmonellae types was added to the mixture prior to ensiling to obtain recovery data. Ninety-two percent were recovered in the fresh waste when tests were carried out prior to ensiling. None were recovered after ensiling three days at 25°C (see Table 431. After ensiling for 4 days, 78 percent were recovered when the temperature was 5°C and 93 percent were recovered when the tem- perature was 15°C. When the ensiling temperature was 25°C, 4 percent were recovered; none was recovered when the temperature was 35°C. The minimum acid level for the growth of salmonellae was found to be pH 4.6 to 5.0. At pH 4, growth was completely inhibited. These workers also investigated the effect of a 4-day ensiling period on the growth of a variety of organisms at increasing temperatures. Yeasts and molds were greatly reduced, coliforms eliminated, and acid-producing bacteria in- creased by low temperatures then decreased greatly at the higher temper- atures (see Table 441. Spore-forming bacteria were fairly stable in number regardless of temperature, although anaerobic spore-formers were reduced TABLE 43 Survival of Salmonellae in Cattle Waste and in an Ensiled Waste-Feed Mixturea Waste Mixture Percentage recovery 92 0 pH, initial 6.8 6.5 pH, 3 days 6.0 4.5 aRecovery after 3 days incubation at 25°C. SOURCE: McCaskey and Anthony (1975).

154 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS TABLE 44 Effect of Temperature on Survival of salmoMellae in an Ensiled Waste-Feed Mixture Temperature (°C) Survival After 4 Days Ensiling 5 15 25 35 Number of culturesU 21 25 1 0 Percent of cultures 78 93 4 0 pH, initial 4.8 4.8 4.8 4.8 pH, 4 days 4.6 4.4 4.0 4.1 a27 salmonella cultures were used. SOURCE: McCaskey and Anthony (1975). at higher temperatures (15°C or above). At 5°C the numbers of aerobic spore-formers increased. Knight et al. (1977) investigated microbial population changes and fermentation characteristics of ensiled, bovine-waste blended diets. The mixtures contained up to 60 percent waste and were ensiled at 25°C for 10 days. Coliforms were eliminated in mixtures with 40 and 60 percent waste after 5 days of ensiling and after 10 days in the 20 percent mixture. Salmonellae were isolated twice prior to ensiling but were not isolated after 3 days of ensiling. Spore-forming bacteria survived but did not proliferate in the ensiled mixtures. Reduction in bacterial contamination was related to a reduction in pH to around 4.5. Yeasts and molds were reduced from around 106/g to around 104/g after ensiling for 10 days. Caswell et al. (1978) found that coliform bacteria in broiler litter were eliminated by ensiling at 25 to 50 percent moisture. Proteus organisms were destroyed by ensiling at all moisture levels tested. These studies indicate that the beneficial effects of ensiling can be attributed to two causes, heating and the development of acid. Ensiling also has a beneficial effect on contamination with parasitic nematode larvae. Ciordia and An- thony (1969) found that feedlot waste contained viable larvae, but none was present in the silage made from waste and dry hay. Farquar et al. (1979) reported that sporulation of bovine coccidia was prevented by ensiling a waste-blended diet. A number of reports indicate the beneficial effects of heat processing. Fontenot et al. (1970) found no adverse effects in sheep fed for 80 days on diets containing up to 75 percent poultry litter that had been sterilized by dry heat at 150°C for 4 hours. Parameters included physiological observations during the growth period, detailed necropsies, and histolog- ical investigations. Johnson et al. (1975) reported a 91-day test involving

Animal Wastes 155 24 yearling beef calves fed diets containing 0, 10, or 15 percent dehydrated feedlot waste. All animals were necropsied. Gross and histological ex- aminations of rumen, abomasum, small intestine, liver, lung, kidney, trachea, heart, and gall bladder did not indicate any causal relationship between incidence of pathological lesions and waste feeding. Shannon et al. ( 1973) reported on the bacteriological status of 8 samples of dehydrated poultry waste. None was sterile, but the numbers of organisms were low. Found were Anthracoid and Paracolon bacilli, Staphylococci, and Es- cherischia colt. Salmonellae were absent. Caswell et al. (1975) tested four methods of processing broiler litter that was heavily contaminated with bacteria: 1. Dry heating litter 0.6 cm deep at 150°C for 10 to 20 minutes 2. Autoclaving at 5.0 cm deep at 121°C and 105 kg/cm2 pressure for 5 to 30 minutes 3. Dry heating at 150°C for 15 minutes at depths of 0.6 or 2.5 cm after addition of paraformaldehyde at 0 to 5 g/100 g litter 4. Fumigation with ethylene oxide at 22°C at 1 aim for 30 to 120 minutes They found that coliforms were eliminated by all treatments except 30 minutes fumigation. Total bacterial counts were acceptable (20,000/g) after treatment 1 for 20 minutes, treatment 2 for 10 minutes, treatment 3 with 1 to 4 g paraformaldehyde/100 g litter, and treatment 4 for over 30 minutes. Chang et al. (1975) reported the results of a microbiological survey (see Table 45) on dehydrated poultry waste. They found an inverse re- lationship between the temperature of the dehydrator and the number of organisms and between the moisture content of the dehydrated waste and the number of organisms (see Table 464. Below 11 percent moisture the number of organisms was reduced drastically. Only four groups of bacteria were recovered when the dehydration temperature was set at 260°C or above. Blair and Herron (1982? reported that dehydrated broiler litter and layer wastes showed low to scant contamination with E. colt, and no salmonellae. IJnder the California quality control standards for processed waste prod- ucts, the criteria for effectiveness of pasteurization require not more than 20,000 bacteria and 10 coliform organisms/g dried product, and freedom from salmonellae (Helmer, 19801. In assessing the risk of pathogenic organisms associated with processed wastes, it is fair to point out that regular feed ingredients are commonly contaminated. Singh (1974) found that all ingredients tested contained a minimum total microbial count of 12 x 103/g and a mold count of at

156 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS least 3 x 103/g. An average incidence of 4 to 5 percent salmonella contamination of various animal feeds was reported by Allred et al. (1967) and Hauge and Bovre (1958), and outbreaks of salmonellosis in farm stock have been traced to feed and feed ingredients (Boyer et al., 1958, 1962; McClarin et al., 1959; Pomeroy and Grady, 19601. Other possible health hazards associated with feed ingredients include molds and mold toxins (McCaskey and Anthony, 19791. It may be concluded that the health risks from pathogenic organisms associated with the feeding of adequately processed animal wastes are probably no greater than those associated with the feeding of meat meal tankage, blood meal, poultry by-products meal, hydrolyzed poultry feath- ers, offal meal, or processed paunch product, all of which are approved for use in feed. Harmful Substances Minerals The mineral content of animal wastes could lead to at least two potential problems, toxicity and accumulation in tissues or in the environment. However, the data suggest that only the copper content of wastes fed to sheep is of real concern (Fontenot et al., 197 lb). This could be anticipated since it is well known that sheep are very sensitive to the copper level of TABLE 45 Microorganisms Recovered From Samples of Poultry Waste Microorganisms Note Aerobacter aerogenes Alkaligenes faecales Bacillus spp. Clostridium spp. Corynebacterium spp. Enterobacter spp. Escherichia cold Lactobacillus spp. Proteus spp. Streptococcus spp., fecal a a a b a  aBacteria recovered only when dehydration temperature was 260°C or higher. bRecovered only in high moisture samples. SOURCE: Chang et al. ( 1975).

Animal Wastes 157 TABLE 46 Effect of Temperature and Moisture on Microbial Counts of Dehydrated Poultry Waste Sample Dehydration Moisture Microbes Temperature (%)Average Microbial Count/g Aerobic 260°C > 1020,281,666 <10710,000 Over 260°C >106,719,520 <10183,396 Anaerobic 260°C > 106,958,333 ~ 10730,000 Over 260°C >101,360,530 < 1046,241 SOURCE: Chang et al. (1975). the diet. Other elements of concern are mercury, cadmium, lead, arsenic, and selenium. The copper content of animal wastes will vary with the amount added to the diet of the host animal. For instance, copper may be added in the form of copper sulfate as a mold-control agent, in addition to its require- ments as an essential nutrient. The analytical data presented in Appendix Table 4 suggest that the mean content of copper in cattle, swine, and poultry wastes (dry-matter basis) is, respectively, 31.0, 114.2, and 70.3 mg/kg. The range is probably considerable, being 62.8 to 249 mg/kg for swine waste and 31.4 to 300 mg/kg for caged layer waste, according to the values used to derive the means shown in Table 4. Blair (1974) quoted a range of 28 to 109 mg/kg dry matter in dehydrated layer waste. Berryman (1970) reported 675 mg copper/kg dry matter in slurry from swine units in the United Kingdom, where copper was used as a growth stimulant. The dietary level of copper that can be expected to cause problems with sheep is around 15 mg/kg dry matter (Suttle and Price, 19761. Most of the copper in dehydrated waste has been shown to be chemically available; therefore the recycling of animal wastes through sheep constitutes a real hazard unless steps are taken to keep the total dietary copper content at a safe level for this species. Increasing the sulfur and/or molybdenum contents of the diet could be worthwhile to reduce the uptake of copper (Suttle and Price, 19761. Thomas et al. (1972) found that the inclusion of 0, 25, or 50 percent dehydrated poultry waste in diets for growing sheep resulted in normal copper values in the liver and kidney. Other species of farm livestock appear to be much less sensitive to dietary copper level. Webb et al. (1979) wintered cows over 4 years on a diet of 80 percent broiler litter containing up to 160 mg/kg added copper

158 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS and found that performance was unaffected although liver copper value increased from 58.8 mg/kg with a control diet to 561.3 mg/kg with the test diets. They also found that liver copper decreased during the summer when the cows were not receiving litter. Elements other than copper are probably of much less significance in terms of likely hazards in any recycling system. Westing and Brandenberg (1974) fed steers for 184 days on a control diet containing 2.6 mg/kg lead or on a diet containing 14 percent composted feedlot waste that contained 3.6 mg/kg lead. Concentrations of cadmium and lead in the liver of control and test animals were, respectively, 0.062 and 0.567 mg/kg, and 0.041 and 0.460 mg/kg. Thomas et al. (1972) reported that calcium, phosphorus, sodium, po- tassium, magnesium, zinc, iron, copper, and manganese levels in liver and kidney of sheep fed diets containing 0, 25, or 50 percent dehydrated poultry waste were within a normal range. Webb and Fontenot ~ 1975) reported that the inclusion of 25 or 50 percent broiler litter containing copper at a concentration of 230 mg/kg tended to increase liver copper in finishing steers after a 5-day withdrawal period. In a subsequent trial, the feeding of diets with litter containing copper at a concentration of 289 mg/kg increased the level of copper in the liver. Muscle copper tended to be higher in the cattle fed broiler litter in both trials. Westing et al. (1977) fed diets based on 70 percent ensiled corn and 30 percent broiler litter (dry-matter basis) to fattening heifers. Con- centrations of bromine, arsenic, cadmium, copper, mercury, molybdenum, vanadium, and zinc were higher in the litter than in the other feedstuffs. Only liver copper was increased in the cattle fed the corn-litter silage. None of the mineral concentrations were elevated in muscle. Calvert and Smith (1976) conducted a trial in which steers were fed a control diet or a diet containing 12.1 percent dehydrated poultry waste for 400 days. The concentrations of various mineral elements in the test and control diets, respectively, were copper, 17.06 and 4.90 mg/kg; zinc, 62.31 and 30.11 mg/kg; iron, 458.4 and 127.6 mg/kg; cadmium, 0.082 and 0.092 mg/kg; and lead, 0.18 and 0.34 mg/kg. Mineral concentrations in the tissues of animals fed the test and control diets were, respectively, liver copper, 332.5 and 157.7 mg/kg; kidney iron, 261.4 and 243.4 mg/kg; and kidney cadmium, 1.7 and 5.0 mg/kg (dry-matter basis). Several organic arsenicals have been approved for use in poultry and swine diets; therefore attention has to be given to possible arsenical res- idues. The arsenic content of wastes may range from 0.43 to 44 mg/kg (see Appendix Table 51. The current food standards allow up to 1 or 2 mg/kg arsenic in meats, which is much higher than any level found in tissue following the inclusion of waste in the diet. El-Sabban et al. (1970) found that the inclusion of

Animal Wastes 159 poultry litter containing 17 mg/kg arsenic in the diet of sheep resulted in a significant increase in the arsenic content of liver, but not above 0.015 mg/kg. The presence of arsenical residues has been reported in the milk and blood of cows (Calvert and Smith, 1972) and in the tissues of cattle (Webb and Fontenot, 1975) and sheep (Calvert, 1973, 1975) following the feeding of poultry litter. The levels reported by Webb and Fontenot (1975) after a 5-day withdrawal were 0.2 mg/kg (dry-matter basis) at the highest. Polidori et al. (1972) reported on\ the use of dehydrated layer waste containing 0.98 mg/kg arsenic (dry-matter basis). When included in the diet of laying hens at a level of 10 percent, the resultant eggs had 0.32 and 0.37 mg arsenic/kg and control eggs had 0.28 mg/kg, but the dif- ference was not significant. Calvert (1973) studied the retention of arsenic in sheep fed diets con- taining 0, 7, or 14 percent dried broiler waste. The broiler diet contained 3-nitro-4-hydroxyphenyl arsenic acid at 50 mg/kg and resulted in an ar- senic concentration of 42 mg/kg in the waste. About 87 percent of the arsenic was excreted, mainly (76 percent) in the feces. About 2.4 mg arsenic was retained by the sheep, resulting in a tissue concentration of about 0.08 mg/kg. When sheep were given diets containing up to 300 mg/kg arsenic they accumulated amounts proportional to the amounts ingested, mainly in the liver and kidney, though no toxicity symptoms were noted. Concentrations in blood, liver, kidney, urine, and feces fell rapidly after withdrawal of the mineral. Blair and Herron (1982) included poultry waste containing 4 to 31 ma/ kg arsenic at a 10 percent level in broiler diets and recorded the arsenic in liver, leg muscle, and breast muscle. The highest level recorded was 0.25 mg/kg (fresh-weight basis), and there was no correlation between tissue level and treatment. Withdrawal had no obvious effect on arsenic concentration in tissue, possibly because of the 1QW concentrations found. Calvert (1973), however, reported that a withdrawal period of 5 days was efficacious after animals had been fed a high level of arsenic in the diet (273.3 mg/kg as arsanilic acid for 28 days). The concentration of arsenic with no withdrawal was 29.2 mg/kg (dry-weight basis) and 5.0 mg/kg following withdrawal. A withdrawal period of 7 days was required with dairy cows. Vijchulata et al. (1980) reported that tissue mineral levels were altered somewhat in steers fed diets containing un to 25 percent cane layer waste. ~ . . . .. . . ~ (tanner level In liver Increased from 155 to 490 mY/kY and magnesium ~ r _ rat A . 1~ ~-r 1 ~ ~ 1 ~ , ~ ~ 1 ~ and phosphorus in Hackney increased from /Y4 tO bl/ and a,~1: IO ~,~1v mg/kg (dry-matter basis), respectively. Arsenic level in kidney and muscle increased from 0.11 to 0.33 and 0.1 to 0.25 mg/kg (dry-matter basis), respectively, but the levels remained below the safety level of 2 mg/kg

160 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS in liver and 0.5 mg/kg in edible meat established by the Food and Drug Administration . Medicinal Drug Residues and Metabolites Various drugs are used in animal production for medicinal purposes and to improve growth and feed efficiency. Many require a withdrawal period before slaughter to avoid harmful residues in the carcass. It is reasonable to expect that during the period of feeding these drugs will be excreted in the feces and/or urine. Elmund et al. (1971) reported that up to 75 percent of the chlortetracycline in the diet of beef animals was excreted. Bacitracin is not absorbed, and therefore none is expected to appear in edible tissues. According to Donoho (1975), 75 percent of the monensin fed to steers is excreted in the feces as the parent compound. Dehydrated waste from poultry fed the compound contained monensin at a concentration of 10 to 15 mg/kg. Bevill et al. (1978) found that feces and urine from swine fed a diet containing sulfamethazine at a concentration of 100 mg/kg served as a source of the drug for other animals having access to the excrete. Con- centrations of sulfamethazine in the blood of swine having access to the excrete were of sufficient magnitude to result in tissue concentrations exceeding 0.1 mg/kg, the maximum amount allowed in pork according to the Feed and Drug regulations. Zero tolerance of sulfamethazine in pork is allowed under the Canadian regulations. Only limited research has been conducted on medicinal drug residues in animal waste and in the edible products of animals fed the waste. El- Sabban et al. (1970) reported that in steers fed processed poultry waste, chlorinated hydrocarbon compounds in back-fat and arsenic in liver were found in amounts of less than 1 mg/kg. Cregar et al. (1973) reported findings with heifers fed a silage based on broiler wood shavings litter. The birds had been fed diets containing amprolium and ethopabate as coccidiostats, and zinc bacitracin and 3-nitro-4-hydroxyphenyl arsenic acid as growth promoters. Zinc bacitracin at 1.53 and arsenic at 68.52 mg/kg dry matter were detected in the silage, but the other drugs were not detected. No residue of any drug was found in muscle, liver, or fat. Furazolidone levels of 10.2 to 25.1 mg/kg and nitrofurazone levels from 4.5 to 26.7 mg/kg were reported in samples of poultry litter by Messer et al. (19711. Levels of drugs in broiler litter from Virginia are shown in Table 47 (Webb and Fontenot, 1975~. No residues of amprolium or arsenic were detected in the heart, spleen, 12th rib (edible tissue), kidney, kidney fat, liver, or brain of lambs fed poultry litter containing amprolium and 3-nitro-phenyl arsonic acid with

Animal Wastes 161 TABLE 47 Drug Residues in Broiler Litter Concentrationa Number of Drug Average Range Samples Oxytetracycline (mg/kg) 10.9 5.5 - 29.1 12 Chlortetracycline (mglkg)b 12.5 0.8 - 26.3 26 Chlortetracycline (mg/kg)C 0.75 0.1 - 2.8 19 Penicillin (units/g) 12.5 0 - 25.0 2 Neomycin (mg/kg) 0 0 12 Zinc bacitracin (units/8)4 7.2 0.8 - 36.0 6 Zinc bacitracin (units/g)e 12.3 0.16- 36.0 5 Amprolium (mg/kg) 27.3 0 - 77.0 29 Nicarbazin (mg/kg) 81.2 35.1 -152.1 25 aDry-matter basis. Chlortetracycline used continuously in broiler diets. CChlortetracycline used intermittently in broiler diets. Zinc bacitracin used in broiler diets. eZinc bacitracin not used in broiler diets. SOURCE: Webb and Fontenot (1975). and without additional drugs (Brugman et al., 19671. Webb and Fontenot (1975) investigated tissue levels of nicarbazin, amprolium, and chlorte- tracycline in finishing cattle fed diets with 0, 25, and 50 percent broiler litter after a 5-day withdrawal. Chlortetracycline was detected at an average concentration of 41 mg/g in kidney fat from two steers fed 50 percent litter and at a concentration of 34 mg/g in kidney fat from one steer fed 25 percent litter. The Chlortetracycline content of the litter was 12.5 ma/ kg dry matter. No Chlortetracycline was detected in kidney fat from four other steers fed 50 percent litter and from five other steers fed 25 percent litter. No residues of nicarbazin or amprolium were found in any of the tissues of 24 cattle fed litter containing amprolium at a concentration of 42.3 or 51.3 mg/kg. Helmer (1980) reported that monitoring of processed animal wastes in California has suggested that drug residues have not yet posed a problem. These data suggest that drug residues in tissues of animals fed wastes are very low, provided a withdrawal period is allowed before slaughter. Other Mycotoxins are metabolites of fungi and are produced by a variety of species. Many have been found in animal feeds due to the presence of fungi. They are now known to be of importance since they can cause problems in poultry and livestock. Some are also known to be carcino- gen~c.

162 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS Little research has been done on the occurrence or formation of my- cotoxins in animal wastes, although formation of aflatoxins under labo- ratory conditions was demonstrated by Hendrickson and Grant (1971~. Lovett (1972) suggested that poultry litter may be no more of a problem than feed. Blair and Herron (1982) tested dehydrated broiler litter, in- house dried layer waste, and dehydrated layer waste for mycotoxins and were unable to detect aflatoxin, ochratoxin, or zearalenone. Hesseltine (1976) advocated the prevention of mycotoxin formation in foods and feeds rather than detoxification once the toxins had been formed. It would seem sensible to apply the same principle to animal wastes. Since the fungi do not grow on dry substrates, the wastes should be dehydrated rapidly after collection. Another reason for advocating rapid dehydration is that Aspergillus flavus does not produce aflatoxins for 48 hours after spore germination under the most favorable conditions. Residues from chlorinated hydrocarbon pesticide residues and industrial contaminants do not appear to be a problem with the feeding of dehydrated poultry waste according to Smith et al. (19761. Chickens were given feed containing 20 mg/kg PCBs, which was 100 times the U.S. Food and Drug Administration guideline of 0.2 mg/kg for complete animal feeds. When the dehydrated poultry waste was included in a dairy concentrate at 32 percent, the highest PCB residue found in milk fat was 5 mg/kg, which was only twice the guideline of 2.5 mg/kg. Residues dropped rapidly within the first 10 to 15 days after PCB feeding stopped. The behavior of PCBs in the animal is regarded as being similar to that of chlorinated hydrocarbon pesticides and industrial contaminants. A high incidence of abortion was reported in cows that were fed low levels of poultry litter in the wintering ration and were subsequently grazed in the summer on a pasture that had been fertilized with litter (Grief et al., 19694. The cause of the problem was not established. The litter contained estrogenic activity from feeding dienestrol acetate to the birds, a practice no longer approved. The authors suggested that a hormone imbalance was involved, but they pointed out that use of diethylstilbestrol in previous work at higher levels than the estrogenic residues in the waste had not caused abortion. Some producers have been feeding poultry litter to their cow herds for more than 10 years with no abortion problem (Council for Agricultural Science and Technology, 1978~. Quality of Products from Animals Fed Waste A very important question is whether the quality of food products is affected by feeding waste. This has been investigated by a number of workers, some of whom did not use a withdrawal period in their inves . . t~gat~ons.

Animal Wastes 163 No differences in meat quality as judged by chemical analysis or by studies of tenderness, juiciness, or flavor of meat from beef animals fed diets containing up to 50 percent waste were reported by Andersen et al. ~ 1976), Cross et al. ~ 1978), Fontenot et al. ~ 1971 a), Kanev et al. (1971), Vijchulata et al. (19801' and Ward et al. (19754. Cregar et al. (1973) reported that a taste panel of 50 people judged steaks from animals fed broiler litter silage at an average intake of 5.5 kg/day to be slightly less acceptable than steaks from control animals on the basis of tenderness, flavor, and juiciness. This might have been related to a lack of finish in the waste-fed animals. Rhodes (1972) concluded that the tenderness or juiciness of meat from beef animals was not significantly affected by waste feeding, although the flavor of beef from animals fed dehydrated layer waste was judged as being significantly poorer than that of animals fed a control diet or a diet containing litter waste. Five instances of off- flavors were noted but they were not related to treatment. Results with dairy cows fed diets containing up to 36 percent poultry waste suggest no significant effects on milk quality as judged by com- position and flavor (Denisov et al., 1975a; Kristensen et al., 1976; Mello et al., 1973; Silva et al., 19761. Kristensen et al. (1976) reported that after 14 days storage, the milk from cows fed waste had a stronger flavor than control milk. Waste feeding did not affect rennet coagulation of milk, the process of acidification, or the quality of cheese made from it. No deleterious effects as a result of waste feeding have been reported on egg quality (Faruga et al., 1974; Flegal and Zindel, 1971; Kienholz et al., 1975; Vogt, 19731. Biely et al. (1972) reported in one trial that with 20 or 30 percent waste in the diet, eggs had a slightly reduced albumen quality as judged by Haugh unit score. Lee and Bolton (1977) reported no effect on albumen quality or on incidence of shell cracking, but shell weight and shell thickness were poorer with dehydrated layer waste in the diet. Probably this effect could be related to an inadequate level of calcium in the diet. REGULATORY ASPECTS: FEDERAL AND STATE The U.S. Food and Drug Administration has the responsibility of regu- lating animal feeds under the Food, Drug and Cosmetic Act of 1958, which in general specifies the same standards for human food and animal feeds. In 1967 the FDA published a Statement of Policy and Interpretation on the use of poultry litter in animal feed (Title 21 of the Code of Federal Regulations, Section 500.401. This policy statement outlined the FDA position regarding the nonsanctioning of this waste as a feed component on the grounds of possible drug residues and the possible transfer of disease organisms. Subsequently, the regulation was interpreted by the FDA to

164 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS include other waste in addition to poultry litter. However, the agency also interpreted the regulations to mean that regulatory action would not be taken unless the animal waste intended for use in animal feed was found to be adulterated and was to be moved in interstate commerce. Since little animal feed is involved in interstate commerce, the FDA in practice left the responsibility for regulatory action to the states (Taylor and Geyer, 19791. In December 1980 the FDA published a document revoking its policy regarding feeding animal waste, leaving regulation of feeding an- imal waste to the states (Goyan, 19801. The Association of American Feed Control Officials (AAFCO) has developed and revised a model feed bill and model regulations (Association of American Feed Control Officials, 1982:631. These regulations include "AAFCO Official Feed Terms and Feed Ingredient Definitions." Some states have specific regulations providing for use of animal wastes as feed ingredients. These states include California, Colorado, Mississippi, Washington, Alabama, and Virginia. In addition, Georgia, Florida, Or- egon, and Iowa have registered animal wastes as permitted feed ingre- dients. Two categories of animal wastes have been recognized under the state regulations, those with and those without drug residues. In some states a 15- or 30-day withdrawal period is required with the former. The main legislation governing animal feeds in Canada is the Feeds Act ( 1967) which is currently under revision. The feeding of animal wastes is not allowed under this legislation (Jefferson, 1975) on the grounds of potential disease risk, possible mold and mycotoxin problems, and possible problems from residues. Related legislation governing animal products in Canada is the Food and Drugs Act, which specifies standards for drug and chemical residues in meat. Dried layer waste has been given a tentative listing under the Canadian Feeds Regulations. It is defined as undiluted poultry excrete from layer flocks not receiving medication. The proposed clearance is for beef cattle and broiler (roaster) feeds at a level not exceeding 20 or 10 percent, respectively, with a withdrawal period of 15 days before slaughter. RESEARCH NEEDS Variability in composition is a notable feature of animal wastes, and research aimed at improved uniformity is required. This should include studies on collecting and processing systems and on feeding programs for the animals from which the waste is to be collected. Research aimed at improving and maintaining the nutritional value of animal wastes is also required. An integrated animal systems approach should be taken in studies of utilization, for instance the housing of growing turkeys and beef animals

Animal Wastes 165 in adjacent lots. This would minimize handling and transport of wastes, . . . . . . . and maximize nutrient up. Baton. The high moisture content of animal waste needs to be reduced for most feeding systems, but dehydration may not be feasible in the future because of increased energy costs. Alternative ways of reducing dehydration re- quirements, such as predrying in the deep pits of poultry barns, need to be investigated. Research should also be conducted into the use of solar energy for dehydrators. This is distinct from the use of solar energy to produce sun-dried material, which has not had the benefit of pasteurization at a high temperature. Ensiling is an inexpensive and effective method of processing wastes 1 ~ r · ~ ^ 1ntenaec~ for animal feeding. Many organisms are killed by the process, but research needs to be carried out on methods aimed at preventing sporulation of spore-forming organisms. Risks from residues do not appear to be a demonstrable problem in animals fed animal wastes, but research aimed at defining the appropriate withdrawal periods to ensure freedom from residues needs to be conducted. Medicinal drug residues and metabolites, mycotoxins, and mineral ele- ments should be covered in this research. Further work also needs to be conducted on the potential for disease transmission by waste recycling, particularly botulism and related conditions. Further economic studies need to be conducted on the various systems of feeding animal wastes that are currently or potentially in use to deter- mine the overall economic benefits. SUMMARY Animal waste represents a feed resource that is presently not used to its nutritional and economic potential. These wastes are of relatively low energy content, mainly due to a high content of fiber and ash. Consequently, they should be considered for inclusion in diets in which a high energy level is not of primary importance. Another feature of these wastes is that much of the nitrogen is normally present in nonprotein form. This feature, and the presence of fiber, in- dicates that animal wastes are more suited to recycling through ruminants, since these animals possess a digestive tract capable of effectively utilizing both fiber and nonprotein nitrogen. However, it has been shown that swine and poultry are capable of utilizing the true protein and other nutrients present in animal wastes. Animal wastes are variable in composition, and research aimed at improved uniformity and quality is required. The wastes possessing the highest nutritive value are layer waste and broiler litter. They can be processed successfully by either dehydration or ensiling. These wastes contain as much true protein as the common feed

166 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS grains and in addition are useful sources of calcium and phosphorus. The metabolizable energy value of poultry wastes for poultry is about one- half to one-third that of the common feed grains. There appears to be no problem of acceptability. Animals best suited to utilize wastes are probably growing and finishing beef animals, beef breeding stock, growing dairy heifers, dry dairy cows, and sheep. Wet wastes can be utilized successfully in silage systems and to some extent in liquid-feed systems. Dehydrated wastes can be included successfully in high-dry-matter diets for a wide range of animals, and wastes processed in other ways can also be utilized successfully. For best results they should be formulated cor- rectly into diets to prevent imbalances. Several workers have shown that the inclusion of too high a level of waste results in an excessive level of fiber and/or minerals in the diet, with a resultant depression in animal performance. Because of this limitation, up to 10 or 20 percent waste can be included successfully in some animal diets, such as high-energy diets. On the other hand, much higher levels can be used in diets for beef cows (80 percent). Productivity of animals fed diets containing animal wastes is high, and when the diets are fed correctly, animals demonstrate growth rates and production of milk, meat, and eggs equal to those of animals fed traditional feed ingredients. There appears to be only a minimal disease risk with wastes that have been subjected to appropriate processing (dehydration or ensiling). One definable risk involves spore-forming bacteria, which are not destroyed by either process. Further research should be directed to this potential problem. Copper appears to present the only definable mineral problem with the recycling of animal wastes, and only with respect to sheep. This is a quality control problem that requires action on the part of the feeder. The problem of excess copper in sheep diets is well known and is not connected solely with waste feeding. Drug and chemical residues in tissues do not appear to present a major problem as a result of waste feeding' but more research should be con- ducted in this area. It is recommended that waste feeding should be fol- lowed by a withdrawal period of at least 15 days when the waste-fed animal is intended to provide milk, meat, or eggs for human consumption. Food quality does not appear to be affected by feeding waste. LITERATURE CITED Alexander, D. C., J. A. J. Carriere, and K. A. McKay. 1968. Bacteriological studies of poultry litter fed to livestock. Can. Vet. J. 9:127.

Animal Wastes 167 Allred, J. N., J. W. Walker, V. C. Beat, and F. W. Germaine. 1967. A survey to determine the Salmonella contamination rate in livestock and poultry feeds. J. Am. Vet. Med. Assoc. 151:1857. Andersen, H. R., M. Sorensen, J. Lykkeaa, and K. Kousgaard. 1976. Feeding Dried Poultry Waste for Intensive Beef Production. 443. Beret. Forsoegslab., Statens Husdry- brugsudvalg. Anthony, W. B. 1966. Utilization of animal waste as feed for ruminants. Pp. 109-112 in Management of Farm Animal Wastes: Proceedings National Symposium. Publ. SP-0366. St. Joseph, Mich.: American Society of Agricultural Engineers. Anthony, W. B. 1969. Cattle manure: Reuse through wastelage feeding. Pp. 293-296 in Livestock Waste Management and Pollution Abatement: Proceedings International Sym- posium on Livestock Wastes, Columbus, Ohio. St. Joseph, Mich.: American Society of Agricultural Engineers. Anthony, W. B. 1970. Feeding value of cattle manure for cattle. J. Anim. Sci. 30:274. Anthony, W. B. 1971. Cattle manure as feed for cattle. ASAE Pub. Proc. 271:293. Anthony, W. B., and R. R. Nix. 1962. Feeding potential of reclaimed fecal residue. J. Dairy Sci. 45: 1538. Association of American Feed Control Officials. 1982. Model Regulation for Processed Animal Waste Products as Animal Feed Ingredients. Official Publication, Association of American Feed Control Officials. p. 63. Batsman, V. 1973. Dried poultry droppings in feed for cattle. Molochnoe-Myasn. Skotovod. (Kiev) 6:28. Berbeci, C., C. Rarinca, and D. Georgescu. 1975. Use of dried fowl droppings in the intensive fattening of lambs. Lucr. Stiint. Inst. Cercet. Nutr. Anim. 4:107. Berryman, C. 1970. The problem of disposal of farm wastes with particular reference to maintaining soil fertility. P. 19 in Proceedings Symposium on Farm Wastes. Institute of Water Pollution Control, University of Newcastle-upon-Tyne. Bevill, A. F., L. G. Biehl, M. Marshfield, and G. Koritz. 1978. Sulfonamide residues. Proceedings 27th Annual Texas A&M University Swine Shortcourse, April 3-5. Bhargava, K. K., and J. B. O'Neil. 1975. Evaluation of dehydrated poultry waste from cage reared broilers as a feed ingredient for broilers. Poult. Sci. 54:1506. Bhattacharya, A. N., and J. P. Fontenot. 1965. Utilization of different levels of poultry litter nitrogen by sheep. J. Anim. Sci. 24:1174. Bhattacharya, A. N., and J. P. Fontenot. 1966. Protein and energy value of peanut hull and wood shaving poultry litters. J. Anim. Sci. 25:367. Bhattacharya, A. N., and J. C. Taylor. 1975. Recycling animal waste as a feedstuff: A review. J. Anim. Sci. 41:1438. Biely, J., R. Soong, L. Seier, and W. H. Pope. 1972. Dehydrated poultry waste in poultry rations. Poult. Sci. 51:1502. Biely, J., and P. Stapleton. 1976. Recycled dried poultry waste in chick starter diets. Br. Poult. Sci. 17:5. Bjornhog, G., and L. Sjoblom. 1977. Demonstration of coprophagy in some rodents. Swed. Agric. Res. 7:105. Blair, R. 1974. Evaluation of dehydrated poultry waste as a feed ingredient for poultry. Fed. Proc. 33: 1934.  Blair, R., and K. M. Herron. 1982. Growth performance of broilers fed diets containing processed poultry wastes. Br. Poult. Sci. 23:279. Blair, R., and D. W. Knight. 1973` Recycling animal wastes. 1. The problems of disposal, and regulatory aspects of recycled wastes. 2. Feeding recycled wastes to poultry and livestock. Feedstuffs 45(10):32, 45(12):31.

168 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS Bohme, H. 1973. The possible use of dried poultry excrete in feeding. Landwirtsch. Forsch. 28:43. Bohstedt, G., R. H. Grummer, and O. B. Ross. 1943. Cattle manure and other carriers of B-complex vitamins in rations for pigs. J. Anim. Sci. 2:373. Borgioli, E., and M. Tocchini. 1969. Research on the use of sterilized poultry litter on beef-bullocks feeding. Aliment. Anim. 13:263. Bosman, S. W. 1973. Chicken litter in fattening rations for cattle and sheep. S. Afr. J. Anim. Sci. 3:57. Boubedja, M., and H. Marx. 1974. Studies on cattle fattening diets containing poultry litter. Food Sci. Technol. Abstr. 1975. 7 6S756. Boyer, C. I., Jr., D. W. Bruner, and J. A. Brown. 1958. Salmonella organisms isolated from poultry feed. Avian Dis. 2:396. Boyer, C. I., Jr., S. Narotsky, D. W. Bruner, and J. A. Brown. 1962. Salmonellosis in turkeys and chickens associated with contaminated feed. Avian Dis. 6:43. Bressler, G. O., and E. L. Bergman. 1971. Solving the poultry manure problem econom- ically through dehydration. ASAE Proc. 271:81. Brugman, H. H., H. C. Dickey, B. E. Plummer, and J. Gooten. 1967. Drug residues in lamb carcasses fed poultry litter. J. Anim. Sci. 26:915. (Abstr.) Bucholtz, H. F., H. E. Henderson, J. W. Thomas, and H. C. Zindel. 1971. Dried animal waste as a protein supplement for ruminants. ASAE Publ. PROC-271:308. Bull, L. S., and J. T. Reid. 1971. Nutritive value of chicken manure for cattle. ASAE Proc. 271:297. Caldertone, S. H., and H. A. Wilson. 1976. Some Microbial, Drying, and Odor Reduction Studies of Poultry Wastes. Bull. Agric. Exp. Stn., Univ. W. Va. No. 646T. Calvert, C. C. 1973. Feed additive residues in animal manure processed for feed. Feedstuffs 45(17):32. Calvert, C. C. 1975. Arsenicals in animal feeds and wastes. In Arsenical Pesticides. ACS Symp. Ser. No. 7:70. Calvert, C. C. 1976. Systems for the indirect recycling by using animal and municipal wastes as a substrate for protein production. P. 245 in M. Chenost, ed. Proceedings of the Technical Consultation on New Feed Resources. Rome: FAO. Calvert, C. C. 1979. Use of animal excrete for microbial and insect protein synthesis. J. Anim. Sci. 48:178. Calvert, C. C., and L. W. Smith. 1972. Arsenic in milk and blood of cows fed organic arsenic compounds. J. Dairy Sci. 55:706. (Abstr.) Calvert, C. C., and L. W. Smith. 1976. Heavy metal differences in tissues of dairy steers fed either cottonseed meal or dehydrated poultry excrete supplements. Proc. Annul Meet., Am. Dairy Sci. Assoc. 127. (Abstr.) Carriere, J. A. J., D. C. Alexander, and K. A. McKay. 1968. The possibility of producing tuberculin sensitivity by feeding poultry litter. Can. Vet. 9:178. Caswell~ L. F., J. P. FQntenot, and K. E. Webb, Jr. 1975. Effect of processing method · . - ~ . . ~ 1_ _ 1 _ 1 .. _ _ _ _ 1 ~ :, ~ ~: 1: _ ~ ~: ~ _ on pasteurlzatlon ana nitrogen componenls o~ Droller 1ltter anu ol1 11lLI-~eI1 ULlilt~LlU11 by sheep. J. Anim. Sci. 40:750. Caswell, L. F., J. P. Fontenot, and K. E. Webb, Jr. 1978. Fermentation and utilization  of broiler litter ensiled at different moisture levels. J. Anim. Sci. 46:547. Cenni, B., G. Jannella, and B. Colombani. 1969. Poultry litter for feeding table poultry. Ann. Fac. Med. Vet. Pisa, Univ. Studi Pisa 22:276. Chang, T. S., J. E. Dixon, M. L. Esmay, C. J. Flegal, J. B. Gerrish, C. C. Sheppard, and H. C. Zindel. 1975. Microbiological and chemical analyses of anaphage in a complete layer excrete in-house drying system. ASAE Proc. 275:206.

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170 UNDERUTILIZED RESOURCES AS ANIMAL FEEDSTUFFS Egyed, M. N., U. Klopfer, T. A. Nobel, A. Shlosberg, A. Tadmor, I. Zukerman, and J. Avidar. 1978b. Mass outbreaks of botulism in ruminants associated with ingestion of feed containing poultry waste. II. Experimental investigation. Refu. Vet. 35:100. Elmund, G. K., S. M. Morrison, D. W. Grant, and M. P. Nevins. 1971. Role of excreted chlortetracycline on modifying the decomposition process of feedlot waste. Bull. Environ. Contam. Toxicol. 6:129. El-Sabban, F. F., J. W. Bratzler, T. A. Long, D. E. H. Frear, and R. F. Gentry. 1970. Value of processed poultry waste as a feed for ruminants. J. Anim. Sci. 31:107. Esmay, M. L., C. J. Flegal, J. B. Gerrish, J. E. Dixon, C. C. Sheppard, H. C. Zindel, and T. S. Chang. 1975. Inhouse handling and dehydration of poultry manure from a caged layer operation: A project review. ASAE Publ. PROC-275:468. Evans, E., E. T. Moran, Jr., and J. P. Walker. 1978a. Laying hen excrete as a ruminant feedstuff. I. Influence of practical extremes in diet, waste management procedures and stage of production on composition. J. Anim. Sci. 46:520. Evans, E., E. T. Moran, Jr., G. K. Macleod, and E. M. Turner, Jr. 1978b. Laying hen excrete as a ruminant feedstuff. II. Preservation and acceptability of wet excrete by sheep. J. Anim. Sci. 46:527. Evvard, J. M., and K. K. Henness. 1925. An experiment to study on hogs following cattle. P. 55 in Proc. Am. Soc. Anim. Prod. Farquar, A. S., W. B. Anthony, and J. V. Ernst. 1979. Prevention of sporulation of bovine coccidia by the ensiling of a manure blended diet. J. Anim. Sci. 49:1331. Faruga, A., H. Puchajda, and T. Mazur. 1974. Cattle manure in feeds for hens. Zesz. Nauk. Akad. Roln.-Techn. Olsztynie, Technol. Zywn. 129:79. Feldhofer, S., E. Dumanovsky, M. Ostric, B. Rapic, D. Milosevic, B. Smalcelj, L. Milakovic-Novak, M. Lucic, A. Svalina, D. Haberstok, and A. Gjuric. 1975. Changes in poultry waste during processing and storage and its value in feeding ruminants. 2. Comparison of chemical analyses of fresh poultry waste kept for 7, 14 and 21 days. Stocarstvo 29:49. Flachowsky, G. 1975. Studies in the suitability of solid materials in pig feces for use in the feeding of fattening cattle. 1. Procedures and results of fattening trials. Arch. Tier- ernaehr. 25: 139. Flachowsky, G. 1977. Incorporation of decanted solids of pig feces in feed for fattening cattle. 2. Comparison of different types of ration. Arch. Tierernaehr. 27:57. Flachowsky, G., and H. J. Lohnert. 1974. Feeding value of the solids in rabbit feces. Arch. Tierernaehr. 24:611. Flegal, C. J., and H. C. Zindel. 1971. Dehydrated poultry waste (DPW) as a feedstuff in poultry rations. Pp. 305-307 in Livestock Waste Management and Pollution Abatement: Proceedings International Symposium on Livestock Wastes, Columbus, Ohio. St. Joseph, Mich.: American Society of Agricultural Engineers. Flipot, P., M. McNiven, and J. D. Summers. 1975. Poultry wastes as a feedstuff for sheep. Can. J. Anim. Sci. 55:291. Fontenot, J. P., and V. Jurubescu. 1980. Processing of animal waste by feeding to rum- inants. P. 641 in Proceedings of the 5th International Symposium on Ruminant Physi- ology. Lancaster, England: MTP Press. Fontenot, J. P., and K. E. Webb. 1975. Health aspects of recycling animal wastes by  feeding. J. Anim. Sci. 40:1267. Fontenot, J. P., A. N. Bhattacharya, C. L. Drake, and W. H. McClure. 1966. Value of broiler litter as a feed for ruminants. ASAE Publ. SPO 366:105. Fontenot, J. P., R. E. Tucker, B. W. Harmon, K. G. Libke, and W. E. Moore. 1970. Effects of feeding different levels of broiler litter to sheep. J. Anim. Sci. 30:319.

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