Chapter 2
FEEDING ANIMAL WASTES

“Coprophagy… The feeding on or eating of dung or
excrement that is normal behavior among
many insects, birds, and other animals …”

(Webster's International Dictionary, 1890).

2.0 GENERAL

Recycling of animal wastes has always existed in Nature between the same or among diverse species. Rabbits, rats, poultry and pigs are the most typical examples because in specific nutritional situations they consume their own excreta in substantial quantities to meet their requirements of nutrients missing from their diets. Pigs freely roaming in villages leave hardly any poultry or cattle manure unutilized, even when they are fully fed on the “best balanced” diets according to man's view. This phenomenon is attributable to the animals instinct to search for nutrients created by the endogenous synthesis of the enteric microflora.

Eden (1940) found that rabbits produce two types of faeces: the familiar dry pellets during the day, and a soft, mucous type “rarely observed because the animal collects them directly from the anus and swallows them again” at night. A rabbit may eat from 54 to 82% of its own faecal production.

Southern (1940) conjectured that rabbits, by eating their faeces, have the ability to nourish themselves in feed scarcity, cold or danger for several days.

Many trace elements, vitamin K₂, most of the vitamins of the B group and other vitamins or provitamins are found in fresh animal wastes in larger quantities than in the original feed (Müller et al., 1968). In addition to vitamins, faecal wastes contain many unidentified nutritive (growth) factors (UGF) awaiting discovery and identification, as indicated by a wealth of literature of which only examples can be quoted in the context of this study. Thus, Lamoreux and Schumacher (1940) detected more riboflavin in chicken faeces than in their feed. Kennard et al. (1948) observed that the content of riboflavin in chicken faeces increased by 100% when the faeces were kept at room temperature for 24 hours, and by 300% in a week, as a result of bacterial synthesis of the vitamin.

Faecal excreta are considered by the author as a potential source of many supplementary dietary factors for poultry. Elam et al. (1954) reported that chick growth increased when 17.6 ml of a filtered suspension of their litter (autoclaved for 15 min at 15 psi and 121–125°C) was added per kg of their conventional feed. This effect was equivalent to the addition of fish solubles. Daft et al. (1963) reported that rats fed on a diet deficient in pantothenic acid and deprived of coprophagy developed acute clinical manifestations of pantothenic acid deficiency (retardation of growth, loss of weight, and finally death). Coprophagy appears to provide an essential exogenous supply of pantothenic acid and other vitamins synthesized by enteric flora.

The feeding of animal wastes has a history going back a century or more.

In the most recent report of the CAST (1978) it is stated that already in 1908, Henry reported on manure refeeding experiments of the late 1800s and that Henry and Morris in 1920 recommended feeding cattle manure to pigs.

The current trend toward animal waste recycling is motivated by both economic and environmental considerations. The economic potential of utilizing animal wastes as a new feed resource is already of tremendous importance. It will however increase in the near future, because of the rapid accumulation of scientific knowledge and practical results from commercial applications, which will make nutrient recovery from animal wastes attractive for farmers.

The key to the successful application of animal waste recycling at the farm level lies in the ability of extension services to modify technologies already commercially applied and to convince the farmer that he is only by-passing the traditional cycle (soil-plant-animal) for his greater benefit.

An ecologically closed, zero-pollution cycle is an ideal recycling system easy to establish among different animal species. There are many recently applied and prospering recycling systems utilizing animal wastes, most of them, surprisingly enough, in over-populated developing countries of Southeast Asia where population pressure creates the need for new solutions.

While waste recycling among different species is relatively simple to establish, refeeding wastes within the same species is most difficult. A hypothetical recycling situation within the same species and group of birds was demonstrated by Smith (1973); its results are presented in Table 37.

Smith predicted, subject to given assumptions, that within seven cycles the gradual accumulation of undigestibles (minerals, peptidoglycan, ligno-cellulose, etc.) would inevitably preclude the use of the manure in the diet. While the choice of ingredients (low in minerals and ligno-cellulosic constituents) and chemical and mechanical treatments of the manure can to some extent eliminate the undigestibles and theoretically postpone the inevitable trend, it is always more practical to employ an interspecies recycling system or an outlet to fish and/or cropping.

Table 37
EFFECT OF CONTINUOUS CLOSED RECYCLING OF MANURE
ON DIGESTIBILITY AND MANURE PRODUCTION
(% DM)

Assumptions: 1. Digestibility of conventional feed = 80% DM; 2. Digestibility of 1st cycle manure dry matter = 20%; 3. Digestibility of manure DM decreases at the rate of 75% per cycle.

Source: Smith, 1973.

A balanced system of this type should be circular, embracing wastes emanating from urban, livestock and agricultural activities. The schematic flow of such an integrated system is illustrated in Figure 1.

This integration of urban, agricultural and livestock wastes represents a complementary system which can be established on the periphery of urban centres in arid areas for the direct benefit of urban communities. It would enable them to have a supply of fresh animal products and vegetables without seasonal fluctuations because the feed would be based on cheap waste resources. Only a relatively small portion of traditional feed, such as grain, would be required. The system, making use of wastes, would thus release land being utilized for forage so that it could be cultivated for vegetables, horticulture, and field crops.

In view of the fact that feed usually represents 60–90% of total animal production cost, its substitution by processed waste inevitably leads to a significant reduction in the cost of all animal products. This is the key to the economics of feeding waste.

2.1 FEEDING POULTRY WASTE TO CATTLE

Feeding poultry waste (litter and manure) to ruminants is well documented in the literature and is now practised in many countries. The scope and extent of work which has been carried out in previous years is obvious from the volume of publications devoted to the subject in the past two decades.

Table 38
ESTIMATED PRODUCTION OF POULTRY WASTE
(g DM/bird/day)

The quantity of poultry waste produced daily by various classes of poultry is estimated in Table 38.

The nutritive value of these wastes, and hence the levels at which they can be incorporated into cattle rations, varies considerably. However, litter fed at the 40% level can cover almost completely the protein and mineral requirements of beef cattle. An example of the protein contribution of broiler litter containing 20, 25 or 30% crude protein and fed at the 20, 30 or 40% levels (on DM) is calculated in Table 39.

Table 39
BROILER LITTER CONTRIBUTION TO PROTEIN REQUIREMENTS OF BEEF CATTLE

¹ At 12% crude requirement in beef ration (i.e. 120 g/kg of diet).

The data show that even at lower feeding levels (20 and 30%) of broiler litter, the protein requirement will be covered by 33–50 % and at the highest level (40 % broiler litter in the beef ration) from 67–100 % depending upon the quantity of protein in the litter.

Figure 1 — Flow diagram of agro-industrial project

In addition, a significant level of energy and the total requirement of calcium, phosphorus and most other mineral nutrients are fully met when broiler litter is fed at the 20% level.

The ash content of broiler litter is however a factor limiting the level at which the litter can be fed. To incorporate broiler litter into complete rations at levels above 25%, in the mineral content of the litter and counterpart feed ingredients must be carefully regulated so as not to exceed the critical level of ash in the diet. This is even more important in feeding litter derived from replacement birds and particularly from layers. The latter is heavily unbalanced in calcium and phosphorus, and excessive mineral matter in cattle diets, even if otherwise balanced, interferes with digestion, adds to the accumulaton of undigestibles (cell walls, lignin, silica, etc.) and may, particularly in warm climates, suppress the feed intake.

Much however depends upon the counterpart ingredients balancing the ration. Feeds high in ash (rice bran, molasses, etc.) are not good balancing ingredients, and preference should be given to feeds low in ash (sugar, cassava and other tubers, cereal grain, fruit wastes, etc.).

A rough guide for the level of litter incorporation into ruminant diets is as follows:

Several experiments carried out (1969–1974) in Singapore proved that cassava root meal is an excellent donor of feed energy (in place of expensive grain) in dried or ensiled poultry litter-based rations for beef cattle (Müller, 1974). A similar potential exists for sago (Müller, 1976a). In Malaysia, pineapple cannery waste (Müller, 1978a) is used as the most economic source of energy for cattle fed poultry litter as the main protein source.

2.1.1 Energy-rich wastes as potential counterpart ingredients of poultry waste

Fruit wastes, being rich in digestible energy, sugars in particular, are excellent counterpart ingredients for poultry waste, because of their complementary nutritive properties:

Integrating fruit and vegetable wastes with poultry wastes therefore offers great economic potential for ruminant feeding. Recommended combinations, directly related to energy levels, are shown in Table 40. In these diets the requirements for basic nutrients, protein, energy, calcium and phosphorus are usually met for optimum performance. However, additional energy in the form of molasses and starchy feeds has a great impact on palatability, feed intake and maximum utilization of the NPN fraction of poultry waste.

2.1.2 Pineapple cannery waste/poultry waste cattle project

A project, operating in Malaysia (Müller, 1978a), was designed in 1975 to accommodate over 2,000 head of crossbred cattle on an area of 3.5 ha. Abandoned waste resources (pineapple pulp and poultry waste) are the principal feed ingredients. These are mixed and then fermented (or treated chemically), together with a few chemical supplements. The ration consists of 80% pineapple waste; 10 % poultry litter and poultry droppings; 3% oil-palm wastes; 5% molasses; 1% chemical nutrients; and 1% other chemicals and drugs with antimicrobial, growth promoting and preservative properties. Other formulas used by the project are shown in Table 41.

The ratio of the ingredients is very important to ensure a correct nutrient balance. For example, pineapple waste serves as an important source of readily available carbohydrates in the form of sugars; poultry litter and poultry manure are valuable sources of protein, calcium, phosphorus and other essential nutrients; oil-palm wastes are rich in fats, protein and fibre; molasses is rich in sugar and also increases palatability. Other ingredients are added for overall nutrient balance; this ensures that the nutrients in the wastes are utilized to the full extent.

Table 40
COMBINATION OF POULTRY WASTES WITH FRUIT/VEGETABLE
WASTES FOR RUMINANT RATIONS

¹ Or other energy-rich ingredients such as sugar, root crops, sago, grain, etc.

Table 41
CATTLE FORMULAS BASED ON PINEAPPLE PULPS AND POULTRY WASTE
(% DM)

¹ Or other locally available waste containing above 82% TDN (on DM).
² Urea, minerals, vitamins, etc.

Source: Müller, 1978a.

All these waste resources, by-products and chemicals are processed either in sealed silos or by chemical treatment. Both processes increase palatability, control the acidity of the ration and reduce the bacterial count well below minimum safety requirements. The flow of the process is depicted in Figure 2.

Source : Asia Research Pte. Ltd., Singapore.

Figure 2 — Schematic flow sheet for feed processing plants

The ration contains 14% crude protein and 70% total digestible nutrients (on DM) and an optimum balance of minerals and vitamins. The quantity of feed consumed by the cattle in the feedlot is higher than traditional forages or pastures because of greater palatability. The cost of feed using waste products is less than half the cost of feeding cattle intensively by traditional feed-grain methods.

A carcass evaluation of the feedlot cattle shows a 54–56% dressing percentage, which is unusually high for humid tropical areas and crossbred Bos indicus cattle, and can otherwise be achieved only by feeding expensive grain and other concentrated feedstuffs.

The feeding system can also be applied to breeding cattle and to dairy cows in particular.

2.1.3 Advantages of poultry litter ensiling with forage

The practical potential of ensiling broiler litter with forages or high-moisture grain was demonstrated in several experiments carried out by Virginia scientists (Caswell et al., 1977 and 1978; McClure et al., 1978).

Broiler litter ensiled with high-moisture (26.3%) maize grain was more palatable, measured by feed intake, and gave better performance than soybean used as protein supplement. Similar results were obtained ensiling broiler litter with forage maize. The palatability, live weight gain and carcass quality of finished cattle fed maize-forage broiler-litter silage were much better than that of cattle fed maize-forage silage plus soybean meal.

Dethrow et al. (1976) found that partial and total supplementation of forage-maize silage with soybean meal and dried poultry waste was effective, as demonstrated by satisfactory digestibility of nutrients in all groups, either with or without soybean-meal supplementation.

2.1.4 Feeding to beef cattle

2.1.4.1 Feeding broiler litter

Since the first published experiments of Noland et al. (1955), the use of broiler litter as a feed and forage substitute for beef cattle has been well established (see Table 42).

The estimated numbers of birds required to produce a sufficient quantity of litter per head of beef cattle (average live weight 200 kg), at 20, 30 and 40% litter feeding levels, are as follows:

The usual upper limit for the incorporation of poultry waste into ruminant diets is 40%, but when the level of undigestables (ash, structural carbohydrates) is low and low-cost energy-rich feeds are available (root crops, sugar, molasses, grain, fruit waste, etc.) then the litter level in the ration can be higher. A typical example of this potential is shown in experiments (Müller and Drevjany, 1968) with six groups of 15 Holstein steers of an average initial weight of 283 kg (see Table 43).

Such high levels of litter incorporation were possible only because the litter contained only 12.7% ash, and the ash level of complete diets did not exceed 10% through proper choice of other ingredients.

Based on the results of several other experiments, the industrial production of pelleted cattle ration, using 40% dried broiler litter of standard quality (from a three-million broiler farm), was established by the author (Müller et al., 1968) in 1967. The composition of the pelleted formula was as follows:

A large-scale application of this formula on the one hand and directly-fed dehydrated broiler litter on the other, was carried out as a part of a comprehensive extension programme of the Czechoslovak Ministry of Agriculture and Nutrition on 204 farms holding 21,065 head of cattle in 12 districts. Daily live weight gains ranged from 0.95 to 1.25 kg according to the farm, with a farm average of 1.12 kg (Anon., 1968).

2.1.4.2 Broiler litter for winter feeding of beef cows

Long-term field experiments with wintering beef cows on high levels of broiler litter by Virginia scientists (Webb et al., 1977) have been in course since 1972. In the first three years the feeding ration comprised 75%, and from the fourth year onwards, 80% broiler litter, the balance consisting of ground ear maize. There was almost no grazing. The purposes of the trails were to clarify the effect of long-term feeding of the litter, containing high levels of copper, on the performance of a breeding herd, and to develop simplified methods of management of winter feeding with maximum economic benefits.

Table 42
SUMMARY OF EXPERIMENTS WITH FEEDING POULTRY LITTER TO BEEF CATTLE

Table 44 gives the calving performance of beef cows for the first two years. The performance showed results that favoured the broiler-litter-based wintering ration, and an additional 160 ppm of copper had no negative effect on the number of calves born on birth or weaning weights. The reason for copper supplementation was to ascertain its toxic effect on reproductive performance. Liver samples collected before and after the wintering period indicated that during the summer, when the cows were placed on pasture, the level of copper returned almost to normal, while at the end of the winter period it was very high. The experiment continues.

Table 43
EFFECT OF FEEDING BROILER LITTER ON PERFORMANCE OF FINISHING STEERS

Source: Müller and Dřevjaný, 1968.

¹ Broiler litter analysis (% DM): crude protein = 22.4; true protein 12.2; ether extract = 2.7; crude fibre = 18.9; ash = 12.7;Ca = 1.82; P = 1.57; Moisture of litter = 16.9%‰. All broiler—litter—based rations were pelleted (8 mm pellets).
² Balancing ingredients: wheat flour, feed grade; dry potato flakes; sugar, sugarbeet molasses. Urea was used to make up crude protein to 15% in rations with 30, 40 and 50%. Barley straw was used as a source of “long fibre” as libitum.
³ Control was fed green forage ad libitum and 1.5 kg of conventional feed concentrate with limited access to pasture; feed efficiency data for the control were therefore not established.

Feeding high levels of poultry litter to heifers during the wintering period has been reported by Thornberry et al. (1972). They fed heifers, during the wintering period on a mixture of 72% broiler litter, 22% ground milo and 6% molasses, fortified with vitamin A; the heifers had free-choice salt, bone meal and hay. They gained 550 g/head/day at a daily cost of $0.32/kg live weight gain. The researchers found them in excellent condition prior to their release onto spring pasture.

Table 44
BEEF COWS: CALVING PERFORMANCE

Source: Webb et al., 1977.

2.1.4.3 Feeding litter from replacement birds

This litter usually contains about 20% crude protein and 45% TDN, and when fed at 40% level it can substitute about 70% of crude protein, 25% TDN and total requirements for calcium and phosphorus. In feeding litter derived from replacement birds, it is necessary to bear in mind that these birds are fed on more economic rations than broilers, and that their diet therefore comprises milling by-products and other cheaper ingredients with a higher level of ash and fibre. This is inevitably reflected in the higher level of indigestibles (structural carbohydrates, lignin, cutin, silica and total ash) than that found in broiler litter. When formulating beef rations utilizing litter from replacement birds, it is therefore necessary to supplement them with high-caloric feed ingredients to meet the optimum energy requirements.

2.1.4.4 Feeding layer litter

Layer-litter feeding to beef cattle can be recommended up to the 40% level. At this level about 46% crude protein (but only 18% energy) will be contributed by the waste, and therefore it is again important to supplement the ration with high-caloric feed ingredients such as molasses, grain, cassava, sweet potatoes, sago, fruit waste, etc. As layer litter usually contains 3.5–4.5% calcium, additional phosphorus (in the form of ammonium phosphates, sodium phosphates, phosphoric acid, etc.) has to be added to maintain a proper calcium:phosphorus balance. The alkaline nature of layer litter (pH 7.5 to 8.5) can be beneficial when feeding acid silage. It is estimated that about 30 laying birds kept on litter will meet requirements of one beef animal of an average weight of 200 kg.

Cattle farmers in Maine, USA, have successfully fed laying house litter (12–14 months old, containing 23% crude protein) or broiler litter (10 weeks old, containing 21% protein) in a mixture consisting of 75% litter and 25% energy feeds (potato pulp, high-fat hominy, ground maize). The ration was supplemented by dicalcium phosphate and vitamin A, and salt was provided ad libitum.

On free choice, cows consumed 11.4–12.7 kg of the litter mixture and 2.3–2.7 kg of hay. The feed cost was dramatically reduced by using layer litter.

2.1.4.5 Feeding turkey litter

The nutritive value of turkey litter varies considerably, because more bedding material usually reduces the ratio of faecal waste to bedding. Litter from growing turkey usually contains about 14% crude protein, with an estimated value of 40%. Feeding turkey litter at the 40% level contributes about 50% of the crude protein and 20% of the TDN requirements of beef cattle. Turkey litter is usually well balanced in calcium (1.7%) and phosphorus (1.4%). The production of turkey litter per bird/year amounts to about 32 kg (or 88 g per bird/day). Thus, about 22 turkeys reared on litter would meet the requirement of a beef animal but this may vary considerably with the nature of the bedding material, its quantity and overall management.

In the United States, turkey litter has a much higher nutritive value and can be almost equated with broiler litter, so that turkey litter is used there for feeding cattle in the same manner as other poultry litter. Cross and Jenny (1976) reported experiments on Holstein heifers (215 kg average weight) which were given four rations with 0, 15, 30 and 45% turkey litter. All rations contained 10% concentrate. The best daily gains were obtained with silage containing 15% turkey litter (580 g) and 30% litter (520 g), compared with the control without turkey litter (430 g) or the group fed on 45% turkey litter silage (410 g).

In Europe, from the author's experience, the feeding value of turkey litter is substantially lower, because more bedding material is usually added and because of the semi-intensive nature of turkey growing.

2.1.4.6 Feeding poultry manure

Broiler manure is an excellent protein concentrate containing above 30% crude protein and 60% or more TDN. Because the ash level is somewhat higher than in broiler litter, it is difficult to incorporate manure in cattle rations above the 30% level. That level will substitute about 75% of the total crude protein and 24% of the TDN requirements. One broiler produces about 4 kg (DM) droppings per year or about 11 g per day. About 105 broilers would be required to supply the requirement for one average head (200 kg) of beef animal.

Replacement bird manure (24% crude protein, 50% TDN) is also recommended at levels not exceeding 30%. This will cover about 60% of the protein and 20% of the TDN requirements. Replacement birds produce about 5 kg manure per year, or 13.7 g per day. The number of replacement birds required for one beef animal is estimated at 107.

Layer manure (25% crude protein, 40% TDN), when fresh and undecomposed, is an excellent source of protein, but it is low in energy and high in ash and calcium and this imposes limitations on its use. The maximum recommended level is 30%, but it is necessary to balance the phosphorus in the beef ration. At the 30% level, layer manure contributes about 63% of the protein but only 16% of the TDN requirements in beef rations. As a layer produces about 12 kg of manure (DM) per year or 33 g/day, the number of layers required for an average beef animal is approximately 45 birds.

A higher level of layer manure was fed to finishing cattle by German scientists (Felkl et al., 1972). The complete formula was as follows:

This formula contained 10.6% digestible protein and 18.1% crude fibre. In a 181-day finishing experiment, cattle of an initial live weight of 263 kg responded more favourably to this ration, and performance was better, than that of animals on a control ration containing conventional feed ingredients.

Layer manure is usually more palatable when ensiled with forages rich in fermentable carbohydrates (maize, sorghum, sugarcane) or when supplemented with 3% molasses or other sources of soluble carbohydrates to ensure proper lactic fermentation.

2.1.4.7 Effect of feeding poultry waste on carcass quality

Many studies have been carried out on the effect on beef quality when poultry waste is fed to beef cattle.

Fontenot et al. (1964) and Bosman (1973) found slightly lower carcass grades, while Aranjo and Pérez-Buriel (1976) reported a significant difference in dressing percentages in favour of steers fed poultry litter (control 49.9%; litter (maize cobs) 53.6%, litter (groundnut hulls) 55.6% and litter (rice hulls) 53.0%). Nevertheless, most experiments have not recorded significant differences in the carcass or its quality (Drake et al., 1965; Stonestre et al., 1966; Borgioli and Tocchini, 1969a, b; Sommer and Pelech, 1971; Batsman, 1973; and others).

A comprehensive study (Cullison et al., 1976) by the University of Georgia, USA, was designed to identify differences in the quality of carcasses from steers fed two different types of broiler litter and dried poultry manure. The experiment and its main results are summarized in Table 45. Since steers fed rations containing 20% broiler litter based on wood shavings performed in every observed parameter (with the exception of the feed/gain conversion factor) better than controls, economic considerations were obviously in favour of broiler-litter-based rations.

The effect of feeding poultry waste upon carcass quality after long storage of beef was studied by Wooden and Algeo (1976). They fed dried broiler litter to steers at the 0%, 5%, 10% and 15% levels. There were no significant differences among qualities of carcasses stored for 240 days. Neither the feeding level nor the length of time were related to levels of heavy metals, antibiotics or pesticide residues in the tissues.

Table 45
CATTLE FED ON POULTRY WASTES: CARCASS QUALITY

¹ Range 1 (minimum desirability) through 5 (maximum desirability).
² Crude protein content in poultry waste.

Source: Cullision et al., 1976.

2.1.4.8 Concluding remarks, on the feeding of poultry waste to beef cattle

Based on current knowledge, the following major conclusions can be drawn:

1. Poultry wastes can be incorporated in beef rations up to a maximum of 40% dry matter of the complete ration without affecting overall performance and carcass quality.
2. Higher levels of poultry waste—up to 70%—can be used for replacement herds, wintering beef cows and maintenance periods of cattle in general.
3. In feeding poultry wastes to beef cattle, the first limiting factor is energy. High-energy feeds such as grain, root crops, fruit waste and molasses should therefore be incorporated to balance poultry-waste based rations.
4. A secondary limiting factor in feeding poultry wastes, particularly layer wastes, is a high ash content which limits the level of poultry wastes that can be used.
5. Prior to feeding, poultry wastes must be processed by either drying, ensiling, chemical treatment or other processes to reduces the microbial count and eliminate pathogens.
6. Carcass yield and quality are not affected by rations containing poultry wastes, but rations have to be carefully balanced.
7. Incorporation of poultry waste into beef cattle rations has a great impact on the economics of beef production, provided the rations are properly balanced.

2.1.5 Feeding to dairy cattle

Poultry wastes (litter and manure) are good sources of protein and other nutrients for dairy cattle, particularly for low-yielding herds or semi-intensive production.

2.1.5.1 Feeding poultry litter

Poultry litter should not exceed 30 % of the total dry matter requirement in the ration. This level, as shown in Table 46, will supply a substantial portion of protein (31 to 66 %) but the contribution of energy will only be in the range of 16–31 %.

Table 46
CONTRIBUTION OF PROTEIN AND ENERGY FROM POULTRY LITTER
FED TO DAIRY COWS¹

¹ 500 kg live weight, 10 l milk, 3.5 % butterfat;
² at any time to supply 30 % DM of litter per cow;
³ calculated daily requirement per cow: DM est. 12 kg; crude protein 1.37 kg; TDN 6.45 kg.

A survey of experiments with feeding broiler litter to dairy cows appears in Table 47.

These experiments indicate that poultry litter can substitute expensive feed concentrates in dairy rations and thus reduce production costs considerably.

Poultry-based silages and formulas for dairy cattle applied by the author in Indonesia are summarized in Table 48.

These silages, containing 14–15 % crude protein and 61–66 % TDN, can substitute 57–78 % of orages and feeds as shown in Table 49. These formulas meet the requirements of a 550-kg Holstein cow producing 15 l of milk (3.5% butterfat).

Table 47
SUMMARY OF FEEDING BROILER LITTER TO DAIRY COWS

Table 48
DAIRY COW FEEDS: POULTRY WASTE/CASSAVA-BASED SILAGES

Source: Müller, 1978b.

Table 49
DAIRY COW FEEDING: COMPLETE FORMULAS BASED ON POULTRY WASTE/CASSAVA SILAGE

Source: Müller, 1978b.

Cows usually adapt rapidly from fresh green forage or pasture to poultry waste/cassava silage and without any decline in milk production. Silage is quite readily accepted and does not resemble the original ingredients in structure, odour or appearance.

2.1.5.2 Feeding poultry manure

The 25% level of poultry manure in the ration is the optimum for dairy cows. The contribution of the main nutrients, by various classes of poultry manure, fed to dairy cows at that level, appears in Table 50.

Table 50
CONTRIBUTION OF PROTEIN AND ENERGY FROM POULTRY MANURES FED TO DAIRY COWS¹
(25% DM)

¹ 500 kg live weight, 10 l of milk, 3.5% butterfat; calculated requirement per cow/day: DM est. = 12 kg; crude protein 1.37 kg;
² To supply 25% DM of manure per cow.

In high-yielding cows, however, it appears necessary to reduce the level of poultry manure to 10–15% because of increased requirements of higher quality protein from conventional feeds and because an excessive intake of calcium could cause serious metabolic disturbances.

Experiments with feeding dried poultry manure to dairy cows were summarized by Smith (1977) (see Table 51). He concluded that milk production was not affected when 23% of the total dietary protein requirement of dairy cows was provided from dried poultry excreta (DPE). The decreased milk production observed in Thomas et al. (1972) experiments (using 20 to 32% DPE in feed concentrates) appeared to be attributable to the reduction of energy in the total dairy ration rather than to the direct effect of the waste. The quality of milk was not affected by poultry waste.

Table 51
MILK PRODUCTION OF COWS FED RATIONS CONTAINING DPE

¹ Supplemented with conventional feeds.

Source: Smith, 1977.

Van Horn and Silva (1976) fed dairy cows with an almost completely mineralized DPE (containing 60.3% ash and 14.4% calcium) incorporated at the 0, 10, 20 and 30% levels of the total ration. At the 10% level there was no difference in performance, but higher levels of DPE suppressed the performance in a linear manner.

The following conclusions can be drawn concerning the feeding of poultry wastes to dairy cattle:

1. Prior to feeding, poultry wastes should be treated by dehydration, ensiling, chemicals or other suitable processes to reduce the microbial count and totally eliminate pathogens.
2. Poultry wastes can be fed to dairy cattle up to the 25–30% level of DM in the ration, i.e. 4 to 6 kg DM per head/day.
3. The waste can replace more than 60% of the protein requirement, of which 72–85% is digested.
4. High-energy feed ingredients (molasses, sugar, root crops, grain, etc.) must be incorporated in the ration to balance the energy; feeding of larger quantities (above 25% DM) of poultry waste to dairy cows requires ingredients with various kinds of soluble carbohydrates (raffinose, sucrose, starch, etc.) to enhance the utilization of the NPN fraction of the waste to the maximum.
5. The critical constituent of poultry waste is ash, because it reduces the level of organic matter in the complete ration and adds to the total of undigestibles.
6. Poultry wastes from broilers, replacement birds or turkeys, when fed at the 20% level or above, usually supply all the requirements of dairy cows, for calcium and phosphorus, but layer manure or litter, being seriously imbalanced in Ca and P, requires the addition of P to balance the Ca:P ratio.
7. Palatability problems of poultry waste can best be overcome by ensiling or chemical treatment; in feeding dehydrated poultry waste it is necessary to reduce particle size by grinding to provide uniform mixing with other feed concentrates; molasses, despite some contrary views, has a great impact on the palatability and thus the intake of the waste; in addition, it prevents dustiness in the dry concentrate and thus the irritation of the respiratory system and eyes.
8. There is a wide range in the voluntary intake by individual cows, of larger (5 to 6 kg per day) quantities of poultry waste, but adaptation does not take more than 14 days and poultry waste is readily accepted by dairy cows.