PART II (Contd.)

CHAPTER 9
UTILIZATION OF AGRO-INDUSTRIAL BY-PRODUCTS IN LATIN AMERICA

by

C.F. Chicco and T.A. Shultz

Universidad Central de Venezuela - Facultad Ciencias Veterinarias
Maracay - Venezuela

Resumen

Se expone la elaboración, la composición química, los factores Limitantes y Los datos obtenidos en experimentos con animales rumiantes y no rumiantes respecto a 65 subproductos y residuos de cultivos encontrados en las regiones tropicales de América. De acuerdo con La información disponible, se indican los niveles máximos, tratamientos especiales y aditivos para la obtención de respuestas máximas.

Las tortas de semillas oleaginosas son, sin restricciones, fuentes suficientes de proteínas para los rumiantes. Cuando se ha sostituido la harina de soja por harinas de maíz, sésamo y girasol, suplementadas con aminoácidos limitantes, en la alimentación de animales no rumiantes se han obtenido resultados satisfactorios. La harina de algodón exige además sales de hierro y la de rícino un tratamiento de cocción. Los cerdos no comen la harina de palmera oleaginosa africana si se supera el 20 por ciento en la ración, mientras que las aves de corral aceptan la inclusión en ella de un 30 por ciento. La harina de coco fue satisfactoria hasta el 40 por ciento en aves de corral y en ganado porcino. Las partes superiores del algodón, sésamo y maní pueden utilizarse para los rumiantes, siempre que se someta a la primera de las plantas citadas a un tratamiento químico.

Los subproductos de grano y el afrecho y salvado “cilindro” de arroz dan en el ganado vacuno resultados comparables con el del grano descascarado. En la alimentación de los animales no rumiantes no se establecen limitaciones para la harina de gluten de grano, los subproductos de grano y el salvado “cilindro” de arroz si se suplementan con aminoácidos limitantes, mientras que el afrecho de arroz se limita al 25 por ciento en la ración de las aves de corral.

Entre los subproductos de las frutas, las bananas de desecho, las hojas de banana, la harina de mazorca de cacao, el salvado de piña y la pulpa de cítricos no tienen limitaciones importantes para la alimentación de ruminates en grandes cantidades (40 por ciento o más), mientras que la pulpa de café, en cuantía superior al 20 por ciento, tiene efectos depresivos sobre los animales. Se han obtenido resultados satisfactorios con bananas frescas y en polvo en el ganado porcino, habiéndose llegado a suministrar en raciones de engorde hasta un 75 por ciento de la últimas. El elevado contenido de fibra y de cafeina que tiene la pulpa de café limita su utilización por encima del 20 por ciento en la alimentación del ganado porcino. El salvado de piña y la pulpa de frutos cítricos tienen una utilización restringida cuando se destinan al ganado porcino y a las aves de corral, y las semillas de frutos cítricos son tóxicas para estas especies. La mezcla de frutos cítricos puede utilizarse en la alimentación del ganado porcino en sustitución de los cereales, pero en cantidades moderadas.

La melaza de caña se utiliza extensamente como alimento energético para los animales rumiantes o no rumiantes, oscilando la proporción de su uso entre el 5 por ciento, para reducir su carácter polvoriento o mejorar la sabrosidad, hasta el 80 por ciento de la energía metabolizable que es necesaria para el engorde del ganado vacuno para carne. La melaza ha recibido considerable atención como fuente de alimentación energética y vectora de urea para complementar el forraje de baja calidad particularmente durante la estación seca. La proporción utilizable en la alimentación del ganado porcino varía mucho, y los efectos laxantes que ocasionan las dosis superiores al 30 por ciento se corrigen con bagazo o con la adición de grasa. Las cantidades recomendadas en la alimentación de las aves de corral no superan el 15 por ciento. Para los rumiantes conviene utilizar una alimentación rica en melaza.

Entre los subproductos de la yuca, las partes superiores de la planta ricas en proteinas han dado un rendimiento aceptable a la producción de leche con una dosis del 35 por ciento, mientras que en la alimentación de las aves de corral ha dado resultados satisfactorios una dosis del 20 por ciento con adición de metionina y aceite vegetal. La raíz de yuca se ha ofrecido en diverses regímenes alimentarios a rumiantes y no rumiantes. La yuca se ha utilizado como fuente principal de alimentos energéticos para las raciones de destete de terneros, la producción de leche de vaca y el engorde intensivo de vacunos para carne. Se ha conseguido sustituir totalmente el grano con buenos resultados en la alimentación del ganado porcino y de las aves de corral cuando las raciones estaban debidamente equilibradas en cuanto a nutrientes. En la alimentación de los corderos se han obtenido buenos resultados con una dosis del 25 por ciento de resíduos de pulpa y cortezas. Una desintoxicación eficaz de la yuca permite la plena utilización de su valor alimentario.

Actualmente y en un futuro previsible, la función principal de los subproductos agroindustriales y de los resíduos de cultivos será aumentar el suministro, hoy día escaso, de piensos en los trópicos latinoamericanos. Sin embargo, hace falta seguir investigando para determinar major sus ventajas, especialmente cuando se emplean grandes cantidades en la alimentación.

1. INTRODUCTION

Successful animal production requires an adequate supply of feed throughout the year. In tropical America ruminants depend almost exclusively on forages, the dry season being limiting for beef and milk production unless conserved feeds are available. Meanwhile, large amounts of grains are imported to maintain local swine and poultry industries.

The increased future demand for cereals, soybeans and other feeds for direct human consumption dictates that animal industries must adjust to this by making changes in their feeding management and production programmes. This can be done by using higher ration levels of feeds such as forages, by-products, crop residues, wastes and other sources suitable for human consumption.

In tropical America the full utilization of by-products and crop residues would have a grain-saving effect and would notably increase the currently low feed supply for animals. However, full benefit is not at present derived from these feeds because limited information is available regarding their proper use.

Since the poor-quality roughages are dealt with elsewhere in this volume, this review will attempt to summarize the available information on the principal less fibrous agro-industrial by-products and crop residues, commonly found in tropical America, for animal feeding.

2. OILSEEDS

Numerous seeds and fruits are cultivated for their oil content in the Latin American tropics. Those yielding notable volumes of by-product material are cotton, sesame, groundnuts, coconuts, African palm, castor beans and sunflowers.

The principal agro-industrial by-products of these crops are the aerial plant residues following harvest and the cakes remaining after oil removal.

2.1. Oilseed meals. Table 9.1 presents the chemical composition of oilseed meals. In general, all these meals have high protein levels, about 20% for the African palm and coconut and above 40% for the others. Sesame and groundnut meal have low fibre levels, while castor, coconut, African palm and sunflower vary in fibre content according to the oil extraction process and the amount of hulls included. These meals are the main protein sources for animals. Because of their high value for nun-ruminants, they are partially replaced in ruminant feeding by NPN sources.

2.1.1. Cottonseed meal

Cottonseed meal is considered an adequate protein supplement for ruminants and often represents from 20 to 30% of the total ration for lactating cows and fattening steers and lambs. It is also mixed exclusively with 20 to 30% salt as an ad libitum rangeland supplement.

While the gossypol content in the amounts of cottonseed meal fed to cattle has generally been considered non-toxic, observations (McNight, 1968) indicate that when up to 880 ppm gossypol were in the total diet, adding ferrous sulphate to provide an iron:gossypol ratio of 1:1 improved weight gains in cattle. Because of incomplete rumen and microflora development in young calves and lambs, only 10 to 15% is included in concentrate mixes.

Cottonseed meal is generally used safely in swine and poultry rations at levels of up to 10%. When laboratory analyses demonstrate free gossypol levels of less than 0.01%, up to 24% have been used in swine rations without iron additives, with lysine added to the diet (Noland et al., 1968). Higher levels, up to 27%, led to satisfactory swine performance when iron salts were added at an iron/total gossypol ratio of 1:1 (Jarquin et al., 1968).

¹ Feed Composition Tables of Latin America, Univ. of Florida, Gainesville, 1974.

² Göhl, 1975.

Poultry are more tolerant to gossypol than swine; however, 0.25% ferrous sulphate is routinely added in laying-hen rations containing 10% cottonseed meal to prevent mottled egg yolks. When free gossypol levels so dictate, up to a 4:1 iron/free gossypol ratio has been used in layer rations, while a 2:1 ratio is recommended for grower-broiler diets, since these birds are less tolerant to iron (McNight, 1968). With a molar iron/gossypol ratio of 8:1, adequate weight gains were registered in growing chicks on a diet containing 25% cottonseed meal (Armas and Chicco, 1972). At the 30% level, growth was depressed, with the appearance of leg deformities that were overcome by manganese supplementation. Up to a 95% reduction in free gossypol/unit protein has been obtained by cooking and hexane extraction of the seeds, thus improving their biological value for non-ruminant feeding (Bacigalupo et al., 1965). Cottonseed contains average amounts of the essential amino acids as compared with other oilseeds although the lysine content is 2 g/16 gN lower than soybean.

2.1.2. Sesame meal

Sesame meal has been used in various proportions as a protein supplement for both young and mature ruminants, particularly in countries where this crop represents a major source of edible oil. More than 3 kg daily of sesame meal for lactating cows has produced excessive unsaturated fatty acids in butter and disagreeable taste in milk (Göhl, 1975).

Sesame meal is used extensively as a protein supplement for poultry and swine in tropical regions where soybean production is limited. Sesame meal has nearly 1 g/16 gN more methionine and cystine than the average of other oilmeals but the lowest lysine content of any economically important oilmeal. The high phytic acid content of the cake appears to promote a natural chelation and lowering of diet calcium and zinc availability.

Although sesame meal may contain ample amounts of calcium and zinc, these elements have been added in chick diets containing 34% of this oilmeal to obtain optimum results (lease et al., 1966; Cuca and Sunde, 1967). Notable responses to zinc or calcium supplementation were not observed when sesame meal represented 20 to 25% of the ration (Lease and Williams, 1967; Armas and Chicco, 1970a). However, 0.2 to 0.5% lysine additions to all rations cited improved chick growth to comparable rates obtained with soybean meal.

Sesame meal is frequently used in some tropical areas as the principal protein source in both growing and fattening swine rations, representing up to 30% of the diet when a lysine-rich ingredient such as meat meal is incorporated at 5% of the ration (Braham et al., 1962); it has been combined at similar levels with various tropical energy feedstuffs (Chicco et al., 1972a; Chicco et al., 1974). Excessive use of sesame meal may produce soft pork, and when the meal is wetted a disagreeable taste in the meat may occur (Göhl, 1975).

2.1.3. Groundnut meal

The use of groundnut (peanut) meal has no general limitations in ruminant feeding. Replacing protein supplements with the undercorticated meal, relatively lower in protein and higher in fibre, has reduced gains in cattle grazing dry-season savanna, but this was overcome by compensatory response in the following rainy season (Quinn et al., 1966).

The low fibre and high protein contents of decorticated groundnut meal make it a very suitable ingredient for poultry rations. Increasing ration levels of groundnut meal from 8 to 24% for broilers (Chicco, 1976) with lysine and methionine supplementation, gave satisfactory results for both gains and feed conversion.

The low residual oil content of decorticated groundnut meal makes it preferable for swine feeding to minimize the softpork problem. The relatively lower methionine and cystine contents of groundnut meal dictate that other protein feeds rich in these amino acids be included at least at 5% of the ration. Groundnut meal has produced satisfactory swine responses when replacing soybean meal (Rodriguez et al., 1969) and sesame meal (Chicco, 1976) as one fifth of maize-based rations containing several units of sulphur amino acid-rich feedstuffs.

Mouldy groundnuts may contain toxic substances, the most dangerous being aflatoxin, produced by the fungus Aspergillus flavus.

2.1.4. Coconut meal

Coconut meal swells readily when moistened, and old meal has a tendency to become rancid. Coconut meal may increase milk fat and its saturation and improve flavour. Although more than 2 kg of this meal daily to dairy cows may result in tallowy butter, beef cattle can consume more without carcass quality impairment (Göhl, 1975).

Commercial coconut frequently having more than 15% crude fibre, it usually is not included beyond 25% in swine-fattening rations; however, up to 40% may be used, producing a firm fatted hog but at a lowered feed efficiency (Creswell and Brooks, 1971).

Coconut meal is low in lysine, isoleucine, leucine and methionine. This, coupled with its high fibre content, limits its use in poultry rations. Up to 40% have been used in poultry diets when a high energy source and the amino acids mentioned are included. As high as 50% have been used successfully in broiler rations (Chicco, 1976).

2.1.5. Palm kernel meal

Although palm kernel meal may have appreciable oil content, this by-product is usually dry and unpalatable unless mixed with other feedstuffs such as molasses. There are no nutritional limitations to its use in ruminant feeding when it is blended with palatable feeds. In this manner 2 to 3 kg per day have given satisfactory results in adult cattle.

Generally, 20 to 30% palm kernel meal are used in swine rations. Diarrhea may occur with higher amounts, but satisfactory swine-fattening rations have been reported using 62.4% palm kernel meal, 35.1% maize and 2.5% blood meal and produced average daily gains of 643 grams (Göhl, 1975).

Firm pork of good quality has resulted from feeding this meal. In young pig feeding a palatability problem was encountered, as manifested by unacceptable results in swine growing rations including 22% kernel cake (Cardozo and Bateman, 1961).

Palm kernel meal is palatable in poultry rations and is generally used at up to 20% in the diet. Recent observations (Chicco, 1976) indicate acceptable results with 30% in the rations for chicks but reduced gains at a 45% level.

Palm kernel meal is lower in nearly all of the essential amino acids, particularly the sulphur acids, as compared with other oilseed meals found in the Latin American tropics (Roberts, 1974).

2.1.6. Sunflower seed meal

The undecorticated sunflower oilseed meal has been used extensively in ruminant feeding in temperate countries, but only recently has it received attention in the tropics. Although the percentage of fibre is high in the intact seed and the undecorticated oilseed meal, they have been fed to laying hens during the moulting period and to swine. The decorticated meal is highly digestible, with a high-quality protein, and is used freely in balanced feeds owing to the absence of toxic compounds. When the oil content of the meal is high, the keeping quality is relatively poor. High amounts of the meal can cause soft pork.

Sunflower seed meal has been reported more effective than groundnut meal in replacing two thirds of the fishmeal in swine rations (Dorsi et al., 1965). Replacing 50 and 100% of soybean meal or meat by sunflower seed meal gave nearly equal gains over a 108-day growing-fattening swine trial. Sunflower seed has the highest sulphur amino acid content of the major oilseeds and is near or above the average content of other essential amino acids from oilseed sources, except for lysine and leucine (Roberts, 1974).

2.1.7. Castor seed meal

Both the seeds and hulls of castor contain various toxic compounds, among which ricin, a protein, is the principal. They also contain a strong allergen which causes hypersensitivity in humans in contact with the product but apparently not in animals. Ricin can be destroyed by autoclaving or cooking.

Castor seed has less than the average oilseed content of many of the essential amino acids (Roberts, 1974).

Undetoxified castor meal is generally restricted to 5% of the total ration for ruminants. Detoxified castor meal has been fed to lactating dairy cows over a 14-month period (Robb et al., 1974). Diets containing 10 and 20% castor meal, with or without 0.5% added castor oil, were compared with control diets containing 10% cottonseed meal and 0.5% cottonseed oil. No abnormal production or reproduction conditions were noted in test cows, nor was there a notable transfer milk level of ricinine, ricin and antigens. Calves and rats fed milk from test cows showed no apparent muscle residue accumulation nor abnormalities of internal organs.

Poultry appear to be more resistant to the toxins than mammals, and up to 40% castor meal have been used in chick rations (Vilhjalmsdottir and Fisher, 1971). In this trial, boiling four times proved to be the most effective toxin removal method; lysine was determined to be the first limiting amino acid, while tryptophan was the second. This hot-water extraction and amino acid supplementation permitted gains comparable to those produced in isolated soy protein and methionine controls.

2.2 Perspective and Potential. The increased production of synthetic textiles for clothing has reduced cotton production in some tropical areas; however, it still remains an important cash crop and would appear to continue so in the accelerated development of arable lands programmed by the governments of various tropical countries. The tendency to a partial replacement of cottonseed meal for ruminants by non-protein nitrogen will most likely increase, in the light of developments in processing designed to prepare this feed-stuff for non-ruminant consumption. Nonetheless, cottonseed meal will continue to be a major protein supplement for ruminants, owing to the ample inclusion of the fibrous hulls in the commercial meal preparations.

The production pace of sesame oil in certain tropical and sub-tropical countries suggests that the meal by-product will continue to be a primary protein source for non-ruminants in these and adjacent countries. Owing to the competitive use of this meal by non-ruminants, the cost factor will further diminish its use in ruminant rations. Particular attention may be necessary in classifying sesame meal by origin and process method, to clarify mineral imbalances reported in poultry rations based on sesame meal.

Groundnuts are becoming one of the more important annual legumes in the subtropical and tropical zones of Latin America, as well as in other tropical areas of the world. Channelling decorticated meal to non-ruminants and the undecorticated to ruminants would appear to meet both economic and nutritional criteria and therefore is likely to be continued.

Although African palm kernel meal is relatively low in some essential amino acids it is a comparatively safe feedstuff in comparison with other oilseed meals, whose content in toxic compounds calls for additional processes to render them usable. Palm kernel meal may therefore have a more ready usage in areas where additional processing is not available.

Because of the unique properties of castor oil in the field of plastics and nylon, the seed residue will remain a potential feed protein source. Future plant breeding to reduce toxins, or improved detoxification methods, or both, could further increase the value of this feedstuff.

Sunflower seed has been recently introduced in the Latin American tropics. The extent to which its by-products will be used as feedstuffs depends on the adaptability of this crop to tropical environmental and agronomic conditions.

The aerial plant field residues have heretofore been little used as a roughage source for ruminants but this would be an alternative means of utilizing increased amounts of residues in the future.

3. CEREALS

There are few cereal grains suitable to the tropical climate. The principal grains grown in the Latin American tropics are maize and rice. Sorghum grains are also grown, but on a relatively smaller scale. While demands for human consumption consume most of the annual maize production, rice is sometimes in surplus in some tropical areas and is used extensively in animal rations. The major by-products of these cereals are the aerial crop residues, such as maize stover and rice straw, cobs following grain removal and rice hulls, while maize middlings and rice bran and polishings comprise the more nutritive feed by-products after grain processing. Although physical and chemical characteristics for these milling by-products have long been known, a lack of standardization in milling processes, the use of old or faulty milling equipment, and alteration of the by-product by the miller lead to a high variability of these feedstuffs between mills within a country or area of the Latin American tropics.

3.1. Grain-milling by-products. Table 9.2 presents the chemical composition of certain maize and rice by-products. Generally, these by-products have a moderate protein content, between 8 and 14%, and a variable level of fibre, about 6% for rice polish and maize middlings, and over 20% for bran and rice mill feed.

No general limitations are set for maize middlings in poultry feeding if supplemented with the limiting amino acids. When containing a high fat level they may cause soft fat in pigs if fed at more than 0.5 kg/animal/day.

The increasing human demands for maize in the Latin tropics and the increase of internal rice surpluses in some countries of this area have accelerated the use of rice and rice by-products for livestock feeding.

Paddy rice, off-coloured class III rice and broken rice are used without nutritional limitation for cattle feeding on farms and ranches near rice-growing areas. Rice bran and polishings are also used extensively in a wide range of cattle-feeding circumstances (Carnevali et al., 1970; Shultz et al., 1971; Shultz, 1976).

¹ Latin American Feed Tables, Univ. of Florida, Gainesville, 1974.

Replacing ground maize completely by dehulled ground rice has given comparable results in broiler rations (Armas and Chicco, 1970b), layer rations (Smith, 1948), turkey poult diets (Treat and Stephenson, 1959) and growing swine (Alvarado et al., 1972), when diets contained sufficient vegetable and animal protein supplements and/or lysine and methionine additions.

Rough or paddy rice has given good results in poultry diets at up to 20 or 30% of the total ration, while up to 50% has been advantageous in swine-fattening rations. Off-coloured and broken rice have been used with similar success.

Rice bran is a valuable by-product feed for non-ruminants, since it is a good source of B vitamins; however, its ether extract content can reach levels of 14 to 18% if it is not processed. This high-oil bran is subject to rancidity and is usually limited to 25% in poultry rations, and to 30 to 40 % in swine rations to avoid soft pork. Higher amounts of deoiled bran have been used successfully.

Rice polishings have a more ample usage in non-ruminant rations than bran, owing to their lower fibre content. Problems similar to these for bran apply to polishings, and more than 30% in the ration has caused scouring. On the other hand, up to 75% rice polishings have been used without problems in some swine-fattening rations (Sagar and Yadava, 1970; Chicco et al., 1974).

3.2. Perspective and Potential. Maize by-products such as gluten, middlings and germ meal will continue to be used primarily for non-ruminants, but competition by demands for human consumption will intensify the need to replace with other, less competitive, energy sources. Owing to their fibrous nature, cobs and stover will remain principally by-products for ruminant consumption. Full utilization of these roughage sources has not been achieved, and they could provide valuable dry matter for ruminants during periods of other roughage scarcities.

Increasing production of rice in the major agricultural areas of the tropics will ensure that its by-products remain a very important energy and moderate protein source for all classes of livestock. The present tendency to using the low-fibre rice grain and grain by-products for non-ruminants and the more fibrous mill feeds, hulls and straw for ruminants would appear likely to continue in the future. Local surpluses of rice grain in some tropical areas suggest that it may be used expediently for all types of livestock.

Physical and chemical treatment of hulls and straw, enabling their increased feeding to ruminants and thus improved residue utilization, should be developed, bearing in mind not only large-scale users of these feedstuffs but also practical methods at the ranch level.

4. FRUITS

A wide variety of tropical fruits and their by-products are available as potential animal feeds in the Latin American tropics, particularly on smaller individual farms. The principal crops grown on an agro-industrial basis are bananas, coffee, cocoa, pineapple and citrus fruits. Other fruits and by-products used to a lesser degree for animals feeds in some areas are mango, papaya and breed-fruit.

Cull or excess fruits, as well as their industrial processing by-products, are standard feedstuffs for animals in the tropics and in many instances may be fed fresh or dried. Owing to the high moisture content of most of them, it is a common practice to ensile them as a means of preservation. Fractional drying can be used to separate by-products from the same source having different nutritive value, such as leaf and stem or pulp and seed separation.

4.1. Fibrous by-products. Table 9.3 presents the chemical composition of the principal fibrous by-products of bananas, coffee, cocoa, pineapple and citrus. The chemical composition of plantain aerial parts are similar to that of bananas.

¹ Göhal, 1975 (Various sources cited)

The protein content is about 2–3% for banana stem and pineapple bran, 6–7% for cocoa pod and citrus pulp and 9–10% for banana leaves, coffee pulp and pineapple leaves. The fibre level, with the exception of citrus pulp and pineapple bran, is above 20%. While the aerial residues of banana and pineapple as well as pineapple bran and citrus pulp are used primarily for ruminant feeding, coffee pulp and cocoa pods are incorporated in both ruminant and non-ruminant rations.

Banana leaves as a roughage source have led to acceptable milk yields (Garcia and De Alba, 1950) and did not appreciably lower calf gains when fed dried and ground to represent up to 60% of the total ration (Garcia et al., 1973). However, these authors suggest that the relatively low palatability, combined with problems in harvesting leaf material, may limit the practicality of using this by-product.

The high moisture content (at least 90%) tends to limit the usefulness of stems or trunks, although they are highly palatable for ruminants.

Up to 20% coffee pulp has been used economically in cattle-fattening and lactating-cow rations for several years on various central Latin American farms. The results generally tend to indicate that feed intake and daily gains are inverse to increased pulp levels in the ration (Jarquin et al., 1973). Results with ensiled or dehydrated pulp have not apparently altered this adverse effect (Braham et al., 1973). The relatively large amount of caffeine (2.4%) in coffee pulp appears responsible for reduced animal performance, while tannins apparently have no effect (Estrada, 1973). Adaptation studies using 30% coffee pulp in steer rations indicate that overall performance can be subsequently improved as compared to animals not previously adapted to the pulp (Cabezas et al., 1974).

The relatively high crude-fibre content of coffee pulp notably reduces its potential as a feedstuff for non-ruminants. However, its essential amino acid content being similar to that of soybean suggests that limited use of this feedstuff could be of economic benefit. Results with growing swine ranging from 12 to 90 kg liveweight have shown that at various stages of growth, weight gains and feed efficiency were inversely related to coffee pulp level in the diet when pulp replaced soy and grain protein in rations having similar fibre contents (Rosales, 1973; Franco et al., 1973). Levels of 16 to 20% pulp in these rations were considered economically acceptable, while higher levels produced significantly inferior results (Jarquin and Bressani, 1976).

Coffee-pulp feeding in chick diets produced high mortality when fed as 30% of the ration. Various treatments, such as cooking, water and solvent extraction and fermentation did not alter these findings. Storage of the feed and progressive adaptation to the diet did however reduce toxicity problems (Bressani et al., 1971).

Fresh coffee pulp has been used as a substrate for torula yeast production and this has successfully replaced 75% of the fishmeal ration and 100% of Vitamin B-complex additives in broiler diets (Gómez, 1970). This could prove a valuable feedstuff if economic production techniques are developed.

Cocoa-pod meal appears similar to maize and cob meal and has maintained comparative milk production levels when representing from 35 to 50% of the ration for dairy cows (De Alba et al., 1954). Similarly, intensive steer gains have been observed when using cocoa-pod meal as 40 or 60% of rations when compared to maize-based fattening diets (Bateman and Larragam, 1966).

The relatively high fibre content limits cocoa-pod feeding to non-ruminants. Up to 50% of the ration has been fed to swine, producing responses slightly inferior to 73% of maize-fed performance (De Alba and Basadre, 1952).

Whole chopped pineapple plant without fruit, fed either as soliage or silage, was comparable to fresh chopped napier grass (Pennisetum purpureum) in both feeding value and milk production (Otagaki and Morita, 1959). From 40 to 60 % pineapple bran and 30% fruitless plant hay have maintained milk and butterfat production satisfactorily (Otagaki et al., 1961) when serving as the sole roughage source for dairy cows.

Sun-dried or ensiled bran has been used in a wide variety of mixtures for beef cattle (O'Donovan et al., 1972). Steers fed 9 kg daily per animal of a 70% sun-dried bran complete mix averaged daily gains of 950 grams. Similarly ensiled mixtures containing 10% molasses and 1% urea led to daily gains of 650 g per animal when fed at a rate of 16 to 18 kg fresh plus 1 kg protein supplement.

The aerial residues of pineapple plants are generally not considered suitable for non-ruminants feeding, owing to their fibre content. Bran has been used in adult swine maintenance rations at levels up to 50%. Pineapple bran and leaf meals adversely affected growth and feed conversion in chick diets (Ross, 1966).

Ruminant nutrient intake from fresh citrus pulp or pulp silage of low DM content may be lower than intensive beef-or milk-production requirements. Where economically feasible, dried citrus pulp has led to more accelerated cattle performance. Feedlot gains have been similar when dried citrus pulp has replaced maize and cob meal in supplements to represent 70% of the concentrate or from 1/3 to nearly 1/2 of the total ration (Shultz et al., 1971; Peacock and Kirk, 1959). Dried citrus pulp was equal to molasses but inferior to cassava meal for tropical lamb weight gains (Chicco et al., 1973). Observations with both finishing beef (Ammerman et al., 1967) and lactating cows (Wing, 1972) indicate that pelleted and unpelleted citrus pulp give similar results, although pelleted meal can provole rumen parakeratosis. Urinary calculi have been observed in steers fattened with rations containing more than 30%, particularly when the citrus pulp was prepared with calcium oxide (Hentges et al., 1966). Lastly, dried citrus pulp can also be used as poultry litter and subsequently fed to ruminants.

Levels of 10% of dried citrus pulp in complete poultry rations will reduce the growth rate markedly, and 2.5% in layer rations will off-colour egg yolks.

4.2. Non-fibrous fruit by-products. Table 9.4 presents the chemical composition of certain low-fibre fruit by-products. The protein content is low in banana pulp (4.2%) and peel (7.9%), and in citrus molasses (5.6%); it reaches 25.3% in cocoa oil cake and 40% in decorticated citrus seed meal. The fibre level is in all cases under 10%.

Bananas and plantains are grown largely for export and domestic human consumption; however, it is estimated that from 25 to 50% of total production within the Latin American tropical region, rejected for export for various reasons, are available as animal feed. Ripe bananas and plantains, fresh or dried, and cooked unripened material are consumed more readily than the unripened uncooked product because of the latter's astringent taste, partly due to the presence of tannins (Von Loesecke, 1950). It is suggested that free or active tannins impart the bitter taste to the unripened fruit and peel, while the bound or insoluble tannins in the ripe product presumably have no effect on palatability. The level of active tannin averages 5 times higher in the peel than in the fruit pulp. Changes in amounts of active tannin during the ripening process, in units per 100 grams of pulp and peel respectively, are 8 and 34 in one-day green material to 2 and 4.7 for nine-day ripe material (Von Loesecke, 1950). There is a similar change from nearly total starch to nearly total sugar during the ripening process of pulp and peel, the predominant sugar being sucrose This process may take an average of 10 days in bananas and several days longer in plantains.

Both green and ripe bananas are palatable to ruminants. They are low in fibre, protein and minerals, and are therefore usually fed with the proper supplements and some roughage source. Similar dairy-cow production has been observed in the use of banana meal and maize at 71% ration levels (Detering et al., 1976). Increasing daily green-banana supplements from 0 to 5 kg per steer led to rises in average daily gains from 460 to 590 grams when grazing guinea grass (Ruiz et al., 1974). Feeding grass or banana pseudo-stems at levels of 0 to 700 grams per 100 kg steer liveweight did not alter the ad libitum consumption of green bananas or the average daily gain, while increasing total protein in the diet from 0 to 600 grams per 100 kg liveweight was linearly beneficial (lsidor and Ruiz, 1975). Additional protein supplementation led to no further improvement. The high percentage of starch in green bananas is apparently a valuable energy source for urea feeding in ruminants. The incorporation of at least 25% bananas starch maximized cattle fattening in diets based on molasses where 60% of the total diet protein equivalent were provided by urea (Herrera and Ruiz, 1975).

¹ Göhl, 1975 (Various sources cited).

The very favourable digestible energy valuses of from 80 to 90% for both fresh green and ripe bananas make them an important energy source in swine diets. Feeding bananas ad libitum to pigs along with a substantial protein supplement to meet specific requirements has been practised for many years (De Alba and Basadre, 1952; Butterworth and Houghton, 1963). Fresh ripe bananas have been fed as the principal energy source to swine throughout their life cycle, with acceptable results when properly supplemented with protein, vitamins and minerals, except during lactation, when the sow, due to the limited gastrointestinal tract capacity, did not consume sufficient energy in the form of fresh bananas (Clavijo and Maner, 1974).

Summarizing various swine-feeding trials (Clavijo and Maner, 1974), it can be concluded that the bitter taste of green or unripe bananas does not permit maximum required consumption; cooking the green material may improve swine performance, but without equalling gains from ripe fruit. The same authors observed that for each increase in maize substitution by banana, there is a small but significant linear decrease in animal performance. This depression is not overcome by increasing protein concentration in the supplement, since the major limiting factor appears to be the 600 kcal/kg lower metabolizable energy from bananas as compared to maize. Although large amounts of ripe bananas may cause diarrhea in pigs, dry green-banana meal has been used at 75% and 50% levels for grower-fattening and gestiation-lactation rations respectively, with acceptable results (Clavijo and Maner, 1974).

Dehydrated green-banana flour has led to inferior poultry performance when exceeding 10% replacement of the grain portion in the ration (FAO, 1969).

Cocoa beans and shells contain the alkaloil theobromine, toxic to animals. The content is relatively quite low in the pods. Cocoa by-products, if cooked in water for about 1 1/2 hours and then filtred and dried, are safe for livestock consumption (Göhl, 1975). The detoxified cocoa oilcake meal received early attention as a feedstuff for swine (Braude and Foot, 1942); however, its higher economic value for human consumption has limited its use as an animal feedstuff.

It has been concluded from a series of observations (Chapman et al., 1972), that citrus molasses can be efficiently utilized in beef finishing rations at levels of 10 to 20% of the concentrate. It is recommended to limit voluntary intake of citrus molasses for grazing animals to about 3 kilos per animal daily, and it is advisable to include protein and phosphorus in the ration when pastures lack these nutrients. On the other hand, citrus molasses can be used satisfactorilly at moderate grain-replacement levels for swine.

The nutritive value of citrus seed meal, when supplying 88% of the total ration protein for lambs, is similar to that of soybean meal in apparent digestibility, net nitrogen retention and biological, value (Amerman et al., 1963). However, citrus by-products that contain seeds are toxic to both swine and poultry: the toxin limonin greatly limits their use for non-ruminants. At the 5% ration level reduced growth is observed in chicks, and mortality occurs at 20% of the ration. Laboratory extraction of the toxican is possible but not economically practical.

4.3. Perspective and Potential. Cull bananas, both green and ripe, obviously constitute an important energy source for tropical farm animals, particularly non-ruminants. Although both pulp and peel of banana and plantain have been used extensively as feedstuffs, considerable amounts of fruit rejected for exportation, are wasted since fruit production areas often do not have animal facilities. The cost of drying has limited the use of banana meal in livestock diets.

Leaf and stem by-product utilization is limited by collection and drying problems due to excess moisture. Fresh feeding or ensiling offers possibilities of partial utilization of this material. Increased use of dried and ground leaf meal, as well as of meal prepared from excess and/or rejected fruit, presents a valuable feed source for all classes of livestock.

In the Latin American tropics, pineapples are not grown extensively in relation to other tropical regions, but production is increasing, and use of these by-products will become more important in the future. Generally speaking, using fresh aerial parts or fruit peelings from the cannery involves materials of high moisture content, whose long-distance transport would be both difficult and expensive without sun- or artificial drying. Ensiling, on the other hand, would appear a useful method for feeding cattle if in the vicinity of the production area.

Many of the considerations relating to bananas and pineapple also apply to citrus by-product feedstuffs.

As with certain other agro-industrial by-products in the Latin tropics, feedstuffs that could be derived from cocoa are produced largely in areas where relatively few livestock are located and the practicality of processing and transportation limits their usage.

Coffee pulp is one of the most abundant agricultural by-products in the Latin tropic coffee-producing countries, which however generally have relatively few by-product processing industries or intensive livestock production systems. Whether the coffee fruit is depulped before bean processing as in Central America, or depulped later as in Brazil, feed preparation of this pulp could reduce a serious disposal problem and create a valuable new industry. Continued efforts are necessary to overcome the inhibitory factors in this feedstuff.

5. OTHER CROPS

Other crops that have notable use as animal feedstuffs in tropical America are sugarcane and cassava.

5.1. Sugarcane. Sugarcane is cultivated in the tropics primarily for sugar production. The harvested cane is pressed, sugar is extracted by water, leaving a nearly sugar-free residue, commonly called “bagasse”. The extract is condensed to a syrup and crystallized by boiling. Crystals and liquid are separated by centrifugation, giving A-molasses. Repeating this process yields B-molasses. When no more sugar can be crystallized, final or blackstrap molasses is obtained. The feeding of sugarcane by-products to ruminants in the Latin American tropics has received much attention, studies ranging from intensive (Prestion, 1974) to limited use of these feedstuffs (Chicco and Shultz, 1974), in diverse feeding circumstances.

5.1.1. Whole cane

Recent attention has been given to the feeding of whole sugarcane to ruminants because of the high vegetal yield per hectare. Comparative feeding tests in steers show that including cane tops with chopped and/or derinded stalks at the natural plant ratio of 30:70 improved voluntary intake and animal performance, though ration digestion was reduced (James, 1973; Ferrero and Preston, 1976). Feeding 14-month matured cane resulted in steer gains nearly double those obtained with immature, 8-month cane (Alvarez and Preston, 1976a). Limited observations suggest that there are no appreciable response differences between animals fed 2 cm coarsely chopped, 5 mm finely chopped, or derinded and pulverized cane (Montppellier and Preston, 1976).

Sugarcane has a protein content (9%) that does not meet ruminant requirements for accelerated growth or milk production. Urea supplementation to represent at least 50% of nitrogen in the ration has been advantageous in improving gains when cattle are fed chopped whole cane or derinded cane (Alvarez and Preston, 1976b; James, 1973). Performed protein supplements have been relatively ineffective with whole sugarcane (López and Preston, 1976), but have been useful with derinded cane (James, 1973). Limited amounts of energy supplements such as maize (James, 1973) or rice polishings (Alvarez and Preston, 1976b), have notably improved steer gains in derinded or whole chopped cane feeding.

Recent use of derinded sugarcane pith (James, 1973) has demonstrated that this feedstuff could effectively represent up to 35% of the ration (32% in the form of raw sugar and the remaining 3% as protein concentrate) to supply about 50% of the total energy for fattening swine. When the derinded cane pith represented 50% of the ration, or about 75% of dietary energy, liveweight gains were significantly reduced. Replacing half of the raw sugar with molasses in similar rations did not alter gains, but complete replacement of the raw sugar with molasses significantly lowered them. Acceptable responses have been observed with broiler rations consisting of 50% derinded cane pith plus sugar/molasses and protein concentrate.

5.1.2. Non-fibrous by-products

Table 9.5 presents the chemical composition of certain non-forage sugarcane by-products. Nitrogen-free extract is the major component, containing mainly sucrose and reducing sugars.

¹ Göhl, 1975

Sugarcane molasses is probably one of the most widely used agro-industrial by-product feedstuffs in the Latin tropics. Differences in sugar type and proportion between the various types of molasses are shown in Table 9.6.

Limited use of molasses in feeding includes the mixing of 5 to 10% in complete rations to reduce dustiness and improve palatability, or 5 to 10% as an additive to enhance silage fermentation and preservation. Molasses may also represent from 15 to 30% of the total ration with a wide range of cattle gains, depending on the digestibility of the ration base (Carrera et al., 1963; O'Donovan and Chen, 1972).

Molasses can be fed as liquid supplement for cattle fed on forage as the basic diet. The liquid supplement often contains phosphoric acid and about 3% urea or other dissolved non-protein nitrogen.

In the dry/wet tropics, molasses supplementation of rainy season pastures will primarily increase carrying capacity (Mott et al., 1967), rather than appreciably improving animal performance per se, because the animal replaces forage energy by the more readily fermentable energy from molasses (Vohnout, 1968; Chicco et al., 1972c; Vicente-Chandler, 1974). On the other hand, molasses and molasses-urea supplements have had a marked effect on cattle production (Mott et al., 1967; Roux and Rodriguez, 1971; Chicco et al., 1972b), and reproduction capabilities (Lesch et al., 1969), when forage and/or nutrient availability is reduced, as during the dry season.

Intensive molasses feeding to ruminants has received detailed attention in the last several years (Preston, 1972). It can effectively represent 80% of the metabolizable energy for fattening beef in the Latin tropic regions, where it is economically accessible. Earlier problems of molasses intoxication can be controlled by a 10-day adaptation of the animals to the diets that includes a limited amount of good-quality roughage.

¹ Göhl, 1975.

Daily animal gains of from 700 to 900 grams have been attained with high levels of molasses-urea (Preston et al., 1967; Elias et al., 1968). As compared with maize, high amounts of molasses (57% DM in the ration) have led to a 20% reduction in total milk yield and total non-fat in the milk (Rodriguez and Preston, 1969). When molasses was offered free-choice, milk yields have been significantly reduced by comparison with restricted molasses intake for cows given ad libitum forage (Sifuentes et al., 1971). Milk production has increased relatively when forage intake was restricted and molasses was the major energy source (Preston and Ugarte, 1971; Molina and Vohnout, 1976).

Limited information on molasses feeding in tropical sheep indicates results similar to those observed in bovines (Chicco et al., 1971; Chicco et al., 1972d; Chicco et al., 1973; Perozo and Vara, 1976).

The availability of molasses in the American tropics and a commercial value relatively lower than that of cereal grain has led to considerable interest in this feedstuff for non-ruminant feeding. Using final molasses at or above 30% in the ration for swine has frequently produced laxative problems and lowered feed efficiency, while high-test molasses has been used at much higher levels without notable problems (Velasquez et al., 1969). The incorporation of 20% sugar in the ration with 40 to 60% final molasses allowed satisfactory growing and finishing swine gains and reduced the laxative effect (Preston and Wills, 1970; Buitrago et al., 1976a). Also, including 13% bagasse (Brooks and Iwanaga, 1967), or 5% mixed fat (Brooks, 1972), or a combination of 5% bagasse pith and 5% anchovy fat (Quijandria and Goncalvez, 1976) has reduced the laxative effect in rations containing 50 to 60% of molasses.

Up to 30% of molasses has been used in poultry rations with acceptable weight gains; however, the liquid feces incidence from molasses levels beyond 10 to 15% may cause management problems (Alvarez et al., 1968; Marin et al., 1968).

Feeding sugar, most commonly unrefined or brown, has been successful at levels over 50% of the ration for swine (Buitrago, 1972) or poultry (Perez, 1971), without digestive problems such as that associated with high levels of final molasses. Combinations of 25% molasses and 75% sugar have yielded acceptable gains in poultry (Perez, 1971; Preston and Willis, 1970). The difference has been suggested to be due to the low mineral content in sugar as compared to that of molasses. Methionine has been indicated as the first limiting amino acid in high-sugar rations for poultry (Perez, 1971). Using 45 to 60% refined sugar for swine has improved gains and feed conversion over 30% or lower ration levels (Maner et al., 1969). Feeding 52% raw sugar to lactating sows did not alter their performance nor that of the litter (Moncada et al., 1975). This amount of sugar allowed protein levels to be dropped from 16% (with 40% sugar) to 10% (with 52% sugar) without altering gestating and lactating sow performance.

Sugarcane juice has been fed satisfactorily in balanced rations at levels of 22.5, 45 and 75% in starter, growing and fattening swine rations respectively, and at levels of 25% in broiler and layer poultry rations (Alexander, 1965; Lishman, 1966). Little information is available regarding molasses distillery by-product feeding.

5.2. Perspective and Potential. The sugarcane industry makes one of the biggest contributions to the feeding of livestock in the Latin American tropics, through either its diverse by-products or the whole or derinded cane. The intensive and effective use of whole or derinded cane for ruminant feeding in some areas is not necessarily to be interpreted as the practice to be followed in other areas. It must be remembered that the molasses, sugar, alcohol and other materials produced from the same cane land could generate considerable employment and monetary benefits for the local economy. The structural insoluble portion of fresh cane is apparently not utilized to an appreciably greater extent than the residual bagasse fibre residue of industrial processing. The soluble carbohydrate fraction from the cane is utilized comparatively more efficiently by the non-ruminant animals. Feeding whole or derinded cane with non-protein nitrogen to ruminants would be advantageous when the soluble energy fraction is not otherwise immediately necessary. The replacement of forage by molasses for ruminants would seem justifiable only in tropical areas having an obvious shortage of forage or molasses excesses above local industrial capacity, or both.

5.3. Cassava. Among the roots and tubers grown in the Latin American tropics are arrowroot, yams, potatoes, cassava and various indigenous crops. Attention will be given to cassava by-products, including the whole root, because of the plant's relatively heavy starch yield per hectare.

Table 9.7 shows the chemical composition of the aerial parts, the cassava root and the principal by-products. While leaves are high in crude protein, N.F.E. is the major component of the cassava root. Cassava leaf protein is low in cystine and methionine, marginal in tryptophan and isoleucine but relatively high in lysine, as compared to soybean meal. The root and the aerial parts contain a water-soluble cyanogenic glucoside which can be destroyed by heat during the drying process.

The fresh roots are highly perishable and deteriorate within a couple of days after harvest if not dried or carefully stored.

5.3.1. Fibrous by-products

Cassava aerial-part feeding has received limited attention due to a lack of, or problems in, mechanical harvesting of the fragile stems and leaves.

Dehydrated cassava leaf and stem meal at the 35% level in dairy-cow concentrates led to an economical milk yield (Echandi, 1952). Although the HCN content varied with the variety of cassava used, no toxic symptoms were observed in ruminants fed hay from aerial parts of different cassava plant varieties (Juarez-Galindo, 1955).

After the starch has been extracted from the cassava root, nearly an equal amount of pulp and peel residue (pomace) remains. This by-product has received little attention as a feedstuff per se. Feeding lambs supplements containing 50% cassava peel and pulp residue, representing 25% of the total ration, has given acceptable results (Shultz, 1976). Replacing as little as 5% of alfalfa meal with cassava leaf meal significantly reduced bird weight gains (Ross and Enriquez, 1969). However, methionine and vegetal oil additives to rations having up to 20% of cassava leaf meal essentially eliminated response depression. Preliminary observations suggest that including cassava leaf meal up to 30% in broiler rations, replacing 75% of oilseed cake protein, promoted acceptable bird growth when the ration was pelleted rather than in mash form (Montilla et al., 1976).

¹ Latin American Feed Tables, Univ. of Florida, Gainesville, 1974.
² Shultz, 1976.

5.3.2. Root feeds

Dried cassava root is consumed by ruminants in different physical forms (sliced, chopped or ground) and has been offered under various feeding regimes. Dried cassava root has given satisfactory results when supplying the principal energy source for dairy-calf weaning rations (Valdivieso and De Alba, 1958), dairy-cow milk production (Assis et al., 1962) intensive beef fattening (Montilla et al., 1970) and lamb growth (Chicco et al., 1971; Chicco et al., 1973). Pressure-cooking cassava meal with urea has given favourable results as a slowed-ammonia release supplement for lambs fed low-quality dry-season tropical forage (Shultz et al., 1972).

Until recent years, diet levels of cassava root were limited to an average of 25 to 30% in the ration (Maner, 1972; Mueller et al., 1974), owing to early reports of cyanide toxicities and/or lowered animal response possibly due to sub-clinic intoxication. More recent observations indicate that much higher levels can be fed.

Feeding up to 58.5% of the ration as cassava root meal, representing a complete replacement of maize, gave similar results to that of maize when protein supplements were increased with the cassava to equalize the rations for swine grown from 40 to 85 kg (Chicco et al., 1972a). Significantly lower gains have been observed with 66% of cassava meal in isoproteic rations (Shimada et al., 1971), when compared to lower cassava or corn diets for younger pigs of 15 to 30 kg liveweight. It has been concluded that total cereal replacement can successfully be achieved with cassava meal when swine rations are properly balanced for other nutrients and a limited amount of molasses is used to enhance palatability (Maner, 1972). Offering cassava fresh or ensiled, either mixed with the protein supplement or fed separately, did not significantly change responses in swine having 20 kg initial weight (Buitrago et al., 1976b). Satisfactory results have been obtained with lactating and gestating sows when fed either fresh or ensiled cassava as compared with basic maize rations (Portela et al., 1976; Saffón et al., 1976).

Complete replacement of maize by cassava root meal has yielded similar egg production, although egg weight was significantly reduced (Pereira da Silva and Tardin, 1971), while in other observations (Enriquez and Ross, 1972), only appreciably less yolk colour was encountered. Replacing 50% of maize meal by cassava meal gave only a slight improvement in broiler gains when compared to a 100% substitution (Armas and Chicco, 1973). Similar broiler gains were observed with a 30 or 60% maize replacement by cassava meal in rations containing 24.5% crude protein (Montilla et al., 1969).

5.4. Perspective and Potential. Considerable attention has been given for many years to the use of surplus cassava-root meal to replace cereal grains in ruminant and, more particularly, non-ruminant feeding in the Latin American tropics. Interest has been focused on the fact that the relatively large production potential per hectare (interestingly on marginal-quality land) of the cassava root to yield energy makes it a very valuable crop to replace maize, in greater demand for human consumption. The fact that this starchy root is a staple of the human masses with modest economic resources in tropical Latin America, and the industrial usage of the starch from this plant raises the inevitable question of competition with direct human utilization. Development of marginal lands to increase cassava production is necessary. The use of the whole cassava plant, root, peel and aerial part, as a surplus by-product of the starch-producing agro-industry may be of some potential in certain areas of the Latin American tropics.

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