| Livestock Research for Rural Development 17 (3) 2005 | Guidelines to authors | LRRD News | Citation of this paper |
Key words: broilers, Cameroon, feedstuffs, maize, protein concentrates
Commercial broiler feed in Cameroon is expensive and therefore out of the reach of small-holder farmers. Maize and protein concentrates traditionally comprise up to 80% of farm-made diets. This use of feedstuffs makes the situation of farm-made diets critical as well. The price of locally produced maize is increasing. Concentrates containing animal proteins used to be imported. However, as from February 2001 the use of meat meals in livestock feeds, including broilers, has been banned in Cameroon. Thus, feedstuffs alternative to maize and meat meals should be sought. Small-holder farmers control up to 72% of the national broiler production (Djoukam and Teguia 1991), but the efficiency of their production is low (Teguia and Beynen 2004). Thus, it is necessary to look for locally available, cheap, safe and nutritionally adequate substitutes for maize and meat meals in broiler feeds. Identification of such feedstuffs would help resource-poor farmers not only to cut down their production costs, but also to improve the efficiency of their production.
The rapid development of intensive broiler production in Cameroon has been accompanied by an increased competition between humans and animals for maize which is a major staple food in the main poultry production zones of the Centre, Littoral and West Provinces (Afrique Agriculture 2002). This competition could be alleviated by replacing maize in poultry feed by locally available agricultural by-products that are less exploited by humans. Two major agricultural by-products, cocoa pod husks and mango kernels, i.e. crop residues usually wasted, have been tested in trials with broilers (Teguia 1995; Teguia et al 2004). Leaves and forages traditionally used for other purposes or even wasted have also been tested, namely sweet potato leaves, bitter leaves, perennial peanuts and Desmodium spp. (Teguia et al 1993; Teguia et al 2002a). In the various studies, the dietary maize component was replaced on a weight basis. Thus, the nutrient composition and digestibility of the test diets differed from that of the control diet. Generally, the feedstuffs under study contained less energy and more protein than did maize. Clearly, the outcome of the studies cannot be unequivocally interpreted in terms of nutrients affecting growth performance. However, the results are important from a practical point of view.
Ground mango kernels (Mangifera indica L) could be used to replace up to 200 g of maize per kg of broiler starter diet, but with some adverse effect on weight gain and feed consumption (Teguia 1995). Increasing the amount of mango kernels in the diet induced a linear depression of feed consumption. Enhanced growth was seen in birds fed on a grower-finisher diet in which 65 g of maize/kg diet was replaced by cocoa husks (Teguia 1982). However, inclusion of 195 g cocoa husks/kg diet depressed performance. High inclusion levels of the two crop residues are contraindicated by the presence of anti-nutritional substances.
The presence of tannins in mango kernels has been reported by Göhl (1982). Tannins are responsible for an astringent taste of the feed that induces a lower feed intake due to reduced palatability (Butler et al 1984; 1986). Tannins may also combine with proteins, including enzymes in the digestive tract and thereby negatively affect the digestibility of proteins (Jansman et al 1995) and carbohydrates, thus reducing the chick's growth rate, the efficiency of feed utilisation and the availability of metabolisable energy of the diet (Rostango 1972). As reported by Laroussilhe (1980), boiling, roasting or soaking could eliminate the astringent taste of mango kernels, thus improving taste and acceptance by the growing birds. Bressani (1993), El-Tahey Shehata (1992) and Iyer et al(1980) also reported on the reduced concentration of tannins in grains treated with boiled water. Thus, it follows that the impact of either cocoa husks or mango kernels versus maize on growth performance of broilers may become beneficial if these crop residues are properly pre-treated to eliminate the influence of tannins.
It would thus appear that boiling of mango kernels and cocoa husks is a good method to get rid of tannins. However, cooking in water may denature protein thus making it unavailable, and may induce losses of vitamins and minerals as has been reported for legume grains (Augustin et al 1981; Bressani 1993). The major difficulty seems to be mastering the cooking conditions under farm conditions in order to obtain the most favourable effects on the animal.
Theobromin present in cocoa husks could be responsible for the declining growth rate of broiler chickens when the husks are fed at high inclusion levels. Alternatively, increasing the proportion of cocoa husks may result in deterioration of the amino acid profile of the diet. Indeed, adding synthetic amino acids to diets containing cocoa husks improved animal production efficiency (Branckaert et al 1967; 1973). The negative effect of cocoa husks on poultry growth may also be explained by the high fibre content of the diets when it has a high inclusion level. An increase in dietary fibre lowers the metabolisable energy content of the diet and may depress the efficiency of feed utilisation. More feed is then required to cover the energy requirement of the bird, thus increasing the cost of feeding.
In general, the replacement of maize with leaves or forages has been more successful in grower-finisher diets of broiler chickens than in the starter phase (Teguia et al 1993; 1996; 2002a). The substitution rate in grower-finisher diets varied from 100 to 300 g/kg diet for Desmodium spp, sweet potato and Vernonia spp leaves, respectively. However, up to 60 g maize/ kg starter diet could be replaced by Desmodium leaves without a significant, detrimental effect on weight gain, feed consumption and feed conversion ratio (Teguia et al 2002a). The major negative factor in these plants was the high fibre content associated with a lower metabolisable energy concentration. On the other hand, the diets containing the leaf meals had a higher protein content. The high fibre level will have induced a poor digestibility of the diets associated with a higher feed consumption and poorer efficiency of feed utilisation. The use of young leaves could alleviate the negative effect of fibre and allow higher inclusion levels. It would therefore be important to determine the optimum harvesting time for each of the leaves so as to obtain optimum nutritional characteristics. This also holds for the tannin content of bitter leaves (Vernonia spp) which is known to affect protein digestion in chickens (Rostango 1972). It may be noted that in addition to its potential as feedstuff for broilers, Desmodium leaves meal may also influence carcass quality. The feeding of Desmodium leaves instead of maize induced a lower amount of abdominal fat, but the effect was not statistically significant (Teguia et al 2002a).
Broiler production in Cameroon has always been dependent on imported sources of protein such as fish meal, soybean meal and animal protein concentrates. These feedstuffs represented a considerable proportion of the production costs, which in turn keeps chicken meat out of the reach of the average consumer. Now, it is prohibited to incorporate animal meals into broiler feeds. Thus, finding locally available protein sources for broilers will contribute to cut down import expenditure at the national level and to deal with legislation.
House fly maggot meal was successfully used to replace up to 6.75 g fish meal/kg starter diet and 20 g/kg grower-finisher diet (Teguia et al 2002b). Maggot meal improved the growth rate and feed consumption of broilers. The overall positive effect of maggot meal on production variables could be due to improved availability of nutrients, possibly essential amino acids. In any event, published feeding studies have shown that dried larvae, which are rich in protein (Sheppard 2002) are a good substitute for soybean or meat meal in the diet of poultry (Calvert et al 1969), swine, and fish (Teotia and Miller 1974 as cited by Sheppard 2002; Gawaad and Brune 1979 and Poluektova et al 1980). The cost of producing broiler meat using a diet containing maggot meal was on average lower than when the diet contained fish meal (Teguia et al 2002b). This result is consistent with reports by Sheppard (2002) and Sheppard and Newton (1999). It should be noted however that so far maggot production was only done under experimental conditions.
In chickens fed on maggot-meal diets there was increase in liver and gizzard size, but no signs of toxicity were observed (Teguia et al 2002b). Indeed, none of the numerous studies on maggots as animal feed has revealed any health problems (Sheppard and Newton 1999). Carcass quality of birds fed maggot meal was similar to that of the controls (Teguia et al 2002b). It can be concluded that maggot meal has potential as a protein source in broiler production, but further research is necessary, including the production of maggots on a large scale.
There has always been interest in legume grains as protein source for broilers as an alternative to soybean meal which traditionally is the staple protein source in poultry diets (Robinson and Singh 2001). As mentioned above, in Cameroon the use of meat meals in animal feeds has been banned recently. Thus, there now is even more interest in legume grains. The replacement of meat meal in the starter diet of broiler chickens by meals of common black bean (Phaseolusvulgaris), Bambara groundnut (Voandzeia subterranean) and/or cowpea (Vigna unguiculata) induced deteriorating effects on growth rate. Only the birds fed on diets with small-grained cowpea (Vignaunguiculata) meal recorded growth rates and feed consumption that were comparable to those of the control group of birds (Teguia et al 2003). During the finishing period however, the groups of broiler birds fed either Bambara groundnut or a 1:1 mixture of Bambara groundnut and large-grained cowpea(Vignaunguiculata L Walp) meal had growth rates comparable to those of the controls, but the control birds consumed significantly more feed than did the groups fed legume grain meal. No significant differences were detected among the treatment groups at the finishing stage with respect to the cost of producing 1 kg of live broiler, whereas during the starter phase, cowpea and a 1:1 mixture of cowpea and common black bean produced significantly cheaper meat than did meat meal (Teguia et al 2003).
In our studies only up to 6% of either cowpea or Bambara groundnut was included in the broiler diets (Teguia et al 2003). Higher inclusion levels would limit the utilisation of legume grains due to the presence of anti-nutritional factors. This statement is supported by previous reports showing that legume seeds may contain variable amounts of the protease inhibitors, trypsin, chymotrypsin and phytohaemagglutinins (D'Mello 1995; Wiseman 1995). The presence of protease inhibitors could be responsible for the depression in growth as reported by Teguia et al (2003) as they interfere with the digestion of proteins. Body weight depression has been also reported in growing pullets and laying hens fed on diets containing untreated grain legumes, although bird performance other than body weight was unrelated to anti-nutritional factors in the grains (Robinson and Singh 2001). Furthermore, many legume seeds are deficient in sulphur containing amino acids. The feeding of diets with legume seeds without added synthetic methionine may further depress growth. Next to methionine, tryptophan is most limiting amino acid in legume grains and its supply deserves attention as well. Enzyme supplements that hydrolyse non-starch polysaccharides increase the metabolisable energy value of grain legumes (Wiryawan and Dingle 1999). It is thus important to assess the feasibility of using enzyme preparations under practical conditions in Cameroon.
All birds fed on diets with legume grains meal consumed significantly less feed than did the control birds (Teguia et al 2003). This could be related to the presence in the grains of condensed tannins (Butler et al 1984), which are known to give an astringent taste to the feed, thus negatively affecting its palatability. Robinson and Singh (2001) reported high levels of condensed tannins in cowpeas, faba beans and norbon beans whereas tannins were not detected in chickpeas or lablab. In addition to diminishing feed palatability, tannins also induce poor feed digestibility because they bind to proteins and reduce the utilisation of carbohydrates (Rostango 1972). Indeed, tannins and protease inhibitors usually raise the feed conversion ratio (Rostango 1972; Butler et al 1984).
To increase utilisation of legume grains by chickens, Robinson and Singh (2001) suggested that the grains should undergo treatment such as dehulling or supplementation of the diet with enzymes. Bressani (2002) reported that dehulling improved protein quality and digestibility of Phaseolus vulgaris and suggested that this could be due to the removal of the seed coat tannins which may cause decreased protein digestibility. Cooking and soaking methods have also been used and the stability of anti-nutritional factors could be reduced by up to 15% (Bressani 2002). Heat treatment has been widely used to improve the nutritional quality of grain legumes, but the major difficulty remains the choice of the type of heat, temperature and environmental conditions. The effect of heat may be specific for each legume and may depend on the concentration and location of the different heat-labile anti-nutritional factors. Thus, research should be carried out to define the proper treatment to enhance the nutritional value of specified legume grains for their use in broiler nutrition on small-holder farms.
(* When original paper is in French, the translated title is in italic.)
Afrique Agriculture 2002 Mensuel d'information sur l'agriculture, l'élevage, la pêche et la forêt en Afrique, Nº 301, Mars 2002, p66.
Augustin J, Beck C B, Kalbfleish G, Kagal L C and Mattews R H 1981 Variation in the vitamin and mineral content of raw and cooked commercial Phaseolus vulgaris classes. Journal of Food Science 46: 1701-1706.
Branckaert R, Vallerand F et Vincent J C 1967 La farine de cabosse de cacao dans l'alimentation des volailles. Rapport de recherche, EFSA, Yaoundé -Cameroun.
*Cocoa husk meal in poultry feeding. Research report.
Branckaert R, Vallerand F et Vincent J C 1973 La farine de cabosse de cacao dans l'alimentation du porc. In Cafe, Cacao, Thé, volume17,n°4, 313-320.
*Cocoa husk meal in pig feeding.
Bressani R 1993 Grain quality of common beans. Food Review International 9:217-297.
Bressani R 2002 Factors influencing nutritive value in food grain legumes: Mucuna in comparison to other grain legumes. In: Mucuna as a Food and Feed: Current Uses and the Way Forward. Edited by M Flores, M Eilittä, R Myhrman, L Carew and R Carsky. Workshop held April 26-29, 2000 in Tegucigalpa, Honduras. CIDICCO, Honduras. Pp. 164-188.
Butler LG, Riedl D J, Lebryk D G and Blytt H J 1984 Interaction of proteins with sorghum tannins: mechanical, specificity and significance. Journal of the American Oil Chemist Society, 61: 916-920.
Butler L G, Rogler J C, Mehansho H and Carlson D M 1986 Dietary effects of tannins. In Cooly V and E Middleton editors. Plant flavonoids in biology and medicine: biochemical pharmacological and structure activity relationship. P 141-157, New York, Wiley.
Calvert C C, Martin R D and Morgan N O 1969 House fly pupae as food for poultry. Journal of Economic Entomology 62: 938-939.
Djoukam J et Teguia A 1991 Filière des produits avicoles au Cameroun: Typologie des élevages avicoles semi-intensifs dans la Province de l'Ouest. Centre Universitaire de Dschang Cameroun., Juin 1991, 41 p.
* Poultry products parthway: Typology of semi-intensive poultry farms in the West Province.
D'Mello J P F 1995 Antinutritional substances in legumes seeds. In J P F D'Mello and C. Devendra, eds. Tropical legumes in animal nutrition. Waltingford, U.K., CAB International p. 135-172.
El Tabey Shehata A M 1992 Hard-to-cook phenomenon in legumes. Food Review International 8: 191-221.
Gawaad A A A and Brune H 1979 Insect protein as a possible source of protein to poultry. Z.. Tierphysiol., Tierernaehr. Futtermittelkde. 42: 216-222.
Göhl B 1982 Les aliments du bétail sous les tropiques: Données sommaires et valeurs nutritives. In FAO, Production et santé animale N° 12, Rome.
Iyer V, Salhunkhe D K, Sathe S K and Rockland L B 1980 Quick-cooking beans (Phaseolus vulgarisL.) . II. Phytate, oligosaccharides and anti enzymes. Plant Food Human Nutrition 30: 45-52.
Jansman A J, Verstegen M W A, Huisman J and Van den Berg J W 1995 Effects of hulls of faba beans (Vicia faba L.) with low or high content of condensed tannins on the apparent ileal and fecal digestibility of nutrients and the excretion of endogenous protein in ileal digesta and feces of pigs. Journal of Animal Science 73: 118-127.
Laroussilhe F 1980 Le manguier. Techniques et productions tropicales. Imprimerie A. Bontemps, Limoges, France, 312 pp.
Poluektova L S, Chaplinskaya K N, Dement'eva T A, Kozlova L S and Ganenkova NM 1980 Effect of adding into the diet of pigs a meal from house-fly larvae on metabolism, development, and meat quality of the pigs. Nauchnye Trudy Novosibirskogo Sel'skokhozyaistvennogo Instituta. 128: 24-27.
Robinson D and Singh D N 2001Alternative Protein Source for Laying. A report for the Rural Industries Research and Development Corporation, Queensland Poultry Research and Development Centre, March 2001, Publication N° DAQ-241A. http://www.rirdc.gov.au/reports/EGGS/00-144sum.html
Rostango H S 1972 Nutritive evaluation of sorghum grains in chicks. PhD thesis. Purdue University, West Lafayette, Indiana, USA.
Sheppard C 2002 Black Soldier Fly and Others for Value-Added Manure Management. http://www.virtualcentre.org/en/enl/vol1n2/article/ibs_conf.pdf
Sheppard C and Newton L 1999 Insect Digestion of Manure. In Lorimor J 2002. Manure management white paper written for the National Center for Manure and Animal Waste Management. AWARE v7.n1.
Teguia A 1982 Utilisation of agro-industrial by-products in animal feeding: Substitution of 0, 10, 20, 30 percents cocoa husks for maize in broiler rations. Final year memoir, National Advanced School of Agriculture, U.C.Ds., Yaoundé-Cameroon.
Teguia A 1995 Substituting mango kernels (Mangifera indica L) for maize in broiler starter diets. Animal Feed Science and Technology 56: 155-158.
Teguia A, Awah-Ndukum J and Puene C 2002a The effects of replacing maize with dried leaves of Desmodium spp on the growth performance of broiler chickens. Bulletin of Animal Health and Production in Africa 50:106-114
Teguia A and Beynen A C 2004 Nutritional aspect of broiler production in small-holder farms in Cameroon. Livestock Research for Rural Development, 16 (1) 2004 http://www.cipav.org.co/lrrd/lrrd16/1/tegu161.htm
Teguia A, Endeley H N L and Beynen A C 2004 Broiler performance upon dietary substitution of cocoa husks for maize. International Journal of Poultry Science 3 (12) : 779-782.
Teguia A , Japou I B and Kamsu E C 2003 Response of broiler chickens to Vigna unguiculat (L) Walp (cowpea), Phaseolus vulgaris (black bean) and Voandzeia subterranean (Bambara groundnut) as feed ingredients in replacement of meat meals. Submitted for publication to Journal of Animal and Feed Sciences.
Téguia A , Mpoame M and Okourou Mba J A 2002b The production performance of broiler birds as affected by the replacement of fish meal by maggot meal in the starter and finisher diets. Tropicultura 4: 187-192.
Teguia A Njwe R M and Nguekouo Foyette C 1996 Effects of replacement of maize with dried leaves of sweet potato (Hypomoea batatas) and perennial peanuts (Arachis glabrata Benth) on the growth performance of finishing broilers. Animal Feed Science and Technology 66: 283-287.
Teguia A, Tchoumboue J, Mayaka B T and Tankou C M 1993 The growth of broiler chickens as affected by the replacement of graded levels of maize by sweet potato leaves (Ipomoea batatas) or Ndole (Vernonia spp) in the finisher diet. Animal Feed Science and Technology 40: 233-237.
Wiryawan K G and Dingle J G 1999 Review: Recent research on improving the quality of grain legumes for chicken growth. Animal Feed Science and Technology 76: 185-193.
Wiseman J 1995 Assigning metabolisable energy values to high fat ingredients. Technical Bulletin, University of Nottingham, Faculty of Agricultural and Food Sciences.
Received 28 June 2004; Accepted 23 December 2004; Published 1 March 2005