6. Supplementary feeding based on agro-industrial byproducts

Sugar cane
Cocoa
Oil seeds
Coffee

Agro-industrial byproducts in the humid tropics are abundant and varied and represent a substantial resource for increasing animal production. The use of these byproducts for supplementary livestock feeding is justified when the forage supply is inadequate for the animals' needs, either in terms of quantity or quality, or when the cost of the supplementation is less than the value of increased animal production achieved. Supplementary feeding is also justified in times of drought or other feed shortages when the importance of providing the animals' immediate nutrient requirements to keep them alive sometimes outweighs other considerations, including the cost of the feed. Concentrate supplements are crucial in such crisis situations, though their quality need not be high. One consideration in the use of supplementary feeds for livestock, however, is possible competition with alternative uses for human consumption, particularly in the case of high-quality feeds.

In the West Indies, strategic supplementary feeding of small ruminants in times of fodder shortage is common, particularly during the dry season. The ingredients used are the byproducts from citrus and coconut cultivation, citrus meal and copra cake, usually in equal proportions (Devendra, 1977d, 1978b). McIntosh et al. (1976) have shown that feeding cottonseed cake at a rate of 0.43 kg per day to Virgin Islands × Persian Blackhead × Barbados Blackbelly sheep is justified economically.

A few trials have been carried out in West Africa to study the effect of supplementation on the main production parameters under field conditions. Ginistry (in CNRZ, 1977) studied the performance of 161 West African Dwarf ewes over a period of 18 months. Out of this group, 53 animals were grazed on natural pasture only throughout the period, 55 received 200 g of rice bran and molasses daily in addition to grazing, and 54 received this supplementation plus a further 400 g of concentrates during the flushing and steaming-up periods in addition to grazing. Half the ewes in each group were also given regular anthelmintic treatment.

The results indicated that the ewes on the most intensive feeding system gained 2.2 kg more during the trial period than the other two groups. They were also more fertile, with a 118% lambing rate compared with 88% for the other two groups. The most intensively fed group produced ten twin births during the period, compared with seven for the intermediate group and six for the group on grazing only, resulting in net lambing percentages of 128.3, 88.3 and 93.3% for the three groups respectively. The increased concentrate feeding during flushing and steaming up did not reduce ewe mortality, but reduced stillbirths and increased the number of pregnancies carried to full term. The anthelmintic treatment, on the other hand, did not appear to be effective: there were no clear differences in weight gain between the animals which were treated and those which were not.

Table 10 lists a number of agricultural byproducts which are used as animal feeds, along with their approximate extraction rates. This list is based on data from Asia: it is not complete and not entirely applicable to other parts of the world. However, a number of the byproducts listed in the table are widely available in Africa and are therefore of interest to this discussion.

Strategies for the effective utilization of various byproducts as animal feeds were recently discussed in depth by an FAO technical consultation on the subject (FAO, 1977). Useful reviews of the utilization of byproducts are presented in this report by Adegbola for Africa, by Chicco and Shultz for Latin America, by Skouri for the Near East and by Devendra for Asia, and the Far East. The general conclusion from these studies is that various widely available byproducts are potentially highly valuable as animal feeds and that considerable increases in goat and sheep production could be achieved on the basis of their more intensive utilization.

Table 10. Byproduct feeds from trees, field crops and animal sources in Asia, with approximate extraction rates

Crop	Byproduct Feed	Approximate Extraction Rate (%)
TREE CROPS
Cocoa beans	cocoa bean waste	5-10
	cocoa husk	70
Coconuts	coconut meal	35-40
Oil palm (fresh fruit bunches)	oil palm sludge (dry)	2
	palm press fibre	12
	palm kernel meal	2
Rubber seeds	rubber seed meal	55-60
Sago trunks	sago refuse	55
Mangoes	mango kernels	50-55
FIELD CROPS
Castor seeds	castor meal	45-50
Cotton seeds	cotton seed meal	40-45
Maize grains	maize bran	8-10
	maize germ meal	16-18
Rice (plants and grains)	broken rice	4-5
	rice bran	10
	rice husk	15-17
	rice straw	100a
Sugarcane plants	bagasse	12-15
	green tops	15-20
	molasses	3-4
Tapioca roots	tapioca waste	55-59
Wheat (plants and grains)	wheat bran	10
	wheat straw	100a
Groundnut (plants and beans)	groundnut vines (stems + leaves)	41-57
	groundnut meal	53-57
Pineapples	pineapple waste	60-80
Sesame seeds	sesame cake	60
Soya beans	soya bean meal	70-75
Sweet potatoes	sweet potato vines (stem + leaves)	24-34
ANIMAL PRODUCTS
Poultry	poultry litter (dry)	26.0b
Ruminants	blood meal	0.6c
	meat and bone meal (dry)	25-30d
	rumen contents (wet)	0.8c

a. Implies weight equivalent to the yield of grains.
b. Based on assumed daily faecal production of 110 g per adult bird.
c. Percentage of liveweight.
d. Percentage of the weight of wet offals.

Source: Devendra in FAO (1977).

To use these byproducts more effectively, their nutritive value can in many instances be enhanced by chemical or physical processing. For instance, possibilities now exist for chemical treatment, particularly of cereal straws, at the commercial and farm level (Homb et al. in FAO, 1977). In India, these processes have been shown to be justifiable economically (Jackson, 1977).

Some of the more important byproducts available in Africa, which could potentially contribute to improved small ruminant feeding programmes, will be discussed in more detail.

Sugar cane

The main byproducts of sugar cane production which are potentially of value as animal feeds are sugar cane tops or leaves, molasses, bagasse and filterpress mud. Sugar cane leaves, if not burnt at harvest time, can be cut and fed to animals. O'Donovan (1970) conducted a feeding trial giving chopped sugar cane leaves to a herd of commercial dairy and beef cattle. The leaves provided enough nutrients to meet the maintenance requirements of all the animals and produce 2 kg of milk daily per dairy cow and 0.25 kg liveweight gain daily per beef animal. Production was further increased when more energy and protein were supplied. Donefer et al. (1975) found in the West Indies that ensiled sugar cane tops fed together with sugar pith produced significantly greater weight gains in cattle than those achieved by feeding sugar pith or pangola grass alone.

Molasses has traditionally been used to supply energy or to increase the palatability of feeds, especially mixed with course roughages. Lofgreen and Otagaki (1960a, 1960b), however, found that net energy was reduced in mixed diets containing more than 10 to 15% molasses, though this varied with the overall feed ration composition. Hatch and Beeson (1972) reported that replacing 5% rolled maize with molasses had no apparent effect, but replacing 10 to 15% increased nitrogen retention, energy and dry matter digestibility and the level of butyric acid in the rumen.

Large quantities of molasses are now available in many tropical countries, and recent advances in its effective utilization have increased the potential importance of this byproduct. In Cuba, reports indicate that molasses may provide up to 80% of the metabolizable energy supplied to beef cattle, and daily liveweight gains of 700 to 900 g were recorded under specific conditions where forage supply was restricted and additional protein was provided by fish meal (Preston et al., 1967; Elias et al., 1968). In Malaysia, Devendra (1975b) investigated molasses-urea diets fed to sheep, with molasses levels ranging from 65 to 78%. He found the optimum rice straw content for maximum digestibility on this regimen was 30% of the feed.

Sugar cane bagasse consists of an outer portion, called the rind, and a finer inner part, known as pith. This is a low-quality feed because of its high ligno-cellulose content. However, Davis and Kirk (1958) reported an increased intake of bagasse with the addition of up to 55% molasses in concentrate diets. Since bagasse is a good carrier of molasses, it can be useful when fed at an optimum level of about 20 to 30% of the diet (Kirk et al., 1962). The nutritive value of bagasse can also be improved by alkali and possibly heat treatment. This has the effect of rendering the complex carbohydrates contained in bagasse more digestible.

Filterpress mud is the product which results from the sugar clarification process. It is composed of the first broth of boiled cane juice plus fine bagasse or pith, and has a relatively high phosphorus content. De Sainte Antoine and Vignes (1962) reported from studies in Mauritius that the inclusion of 20% filterpress mud in the diet of dairy cows gave comparable increases in milk production.

Cocoa

Three cocoa byproducts are useful for animal feeding: cocoa husk, cocoa meal, which is composed of bean fragments, beans and shells, and discarded cocoa bean meal. Of these, cocoa husk is by far the most important.

In Ghana, Owusu-Domfeh et al. (1970) suggested that cocoa husk is a good roughage and a good source of vitamin D (28 IU/g). In Nigeria, it has been proven useful in maintenance diets of sheep and goats (Adeyanju and Ogutuga, 1974), with the optimum portion in the diet of sheep recently estimated at around 30%. The use of cocoa and coconut byproducts in livestock diets has recently been reviewed by Devendra (1978b).

Oil seeds

Byproducts from cotton, coconut, groundnut, soya bean and palm oil production are potentially useful as animal feeds. Of these, the most important are probably cotton and oil palm byproducts. Ogunfowora (1975) reports using up to 30% cottonseed hull for fattening animals in Nigeria, and this byproduct is widely used as a supplementary feed during droughts.

The byproducts of palm oil cultivation are much less widely used, but may become more important in future in view of the significance of this crop in West Africa. Three main palm oil byproducts can be used as animal feed: palm press fibre, palm kernel cake and palm oil sludge. Devendra (1977c) reported from a study conducted in Malaysia that the optimum levels in feed rations were 30% palm press fibre and 40% oil sludge. Palm kernel cake was shown to be a medium-quality source of protein in studies on the utilization of rice straw by sheep (Devendra, 1977c).

Coffee

Ledger and Tillman (1972) showed that the addition of 10 to 20% coffee hulls to the diet of Boran steers did not affect feed intake, conversion or liveweight gains, but performance was reduced when the proportion of coffee hulls was increased to 30%. Coffee pulp has been ensiled with grass and molasses for periods of up to four months, and was proposed by Ogunfowora (1975) as a useful animal feed during the dry season.