Evaluation of performance of broiler chicken fed on cassava flour as a direct substitute of maize

Maize (Zea mays) plays a key role in the poultry industry in Zimbabwe. Because maize is increasingly becoming expensive, it is imperative that alternative ingredients are sought in order to bolster this industry. One hundred and eighty (180) Cobb-500 day-old chicks were used to assess the opportunity of reducing the cost of maize-based diets for broiler production. Effects of incorporating cassava (Manihot esculenta) flour into diets at proportions of 0, 25, 50, 75 and 100% on the performance and carcass composition were investigated under natural conditions in Zimbabwe. Live-weight, feed intake and mortality were recorded and feed conversion efficiency calculated. At 6-week age, carcass samples were analysed for dry matter, ash, crude protein, crude fibre and ether extractable fat. Increased proportion of cassava flour in the diet resulted in a decrease in weight gain, feed conversion efficiency and dressed weight. Crude fibre content of chicken mince increased as maize content decreased in the diets. It is viable to substitute maize for cassava though profit margins fall. Cassava's nutritive value limits its inclusion level and maize will continue to be the major proportion of broiler diets. Key Words: Carcass quality, Manihot esculenta, visceral organs, Zea mays, Zimbabwe RÉSUMÉ Le maïs (Zea mays) joue un rôle important dans l'industrie des poules au Zimbabwe. Comme le prix du maïs augmente avec le temps, il est impératif que les ingrédients alternatifs soient fournies pour stimuler cet industrie. Cent quatre vingts épis, et les poussins vieux de 500 jours étaient utilizés pour évaluer l'opportunuité de réduire le coût de la diète sur base du maïs pour la production des poulets. Les effets de l'incorporation de la farine du manioc (Manihot esculenta) dans la diète avec la proportion de 0, 25, 50, 75 et 100% sur la performance et la composition de la carcasse étaient évaluées dans des conditions naturelles au Zimbabwe. Le poids du poulet vivant, la ratio alimentaire et la mortalité étaient enregistrées et l'efficacité de conversion était calculée. A l'âge de 6-semaines, des échantillons de carcasses étaient analysés pour la matière sèche, le cendre, les protéines brutes, des fibres bruts, et l'efficacité de l'ether à extraire de la graisse. L'augmentation de la farine de manioc dans la diète entraina une réduction du poids du gain, l'efficacité de la conversion de la ratio alimentaire, et le poids de la volaille parée. Le contenu en fibre brut du poulet haché augmenta avec la réduction de la farine de maïs dans la diète. Il est viable de substituer le maïs par le manioc malgré que la marge de profit décroit. La valeur nutritive du manioc limite son niveau d'inclusion, par consequent, le maïs restera la proportion major dans la diète des poulets. Mots clés: Qualité carcasse, Manihot esculenta, organes visceraux, Zea mays, Zimbabwe African Crop Science Journal Vol.12(3) 2004: 267-27

EFFECT OF MAIZE DENSITY, BEAN CULTIVAR AND BEAN SPATIAL ARRANGEMENT ON INTERCROP PERFORMANCE

On-farm trials to determine the optimum combination of maize (Zea mays   L.) density, bean (Phaseolus vulgaris   L.) cultivar and bean spatial arrangement to produce high yields of the intercrop combination were conducted in Chinyika Resettlement Area (CRA) and at Domboshava Training Centre (DTC) during the 1996/97 and 1997/98 rainy seasons. The effects of maize at 37, 000 and 24, 000 plants ha-1, bean cultivars 'Natal Sugar' and 'Carioca', and bean arranged in one or two rows between rows of maize or bean planted in the same row as maize were evaluated in a completed factorial arrangement. Maize density, bean cultivar, bean spatial arrangement and their interactions significantly (P<0.01) affected maize and bean grain yields at both locations for the two seasons. Changing the maize density from 90 x 45 cm (24000 plants ha-1) to 90 x 30 cm (37000 plants ha-1) increased maize yield by 28 and 39% and reduced bean yields by 11 and 18% in the respective seasons. Maize yield was 19% less when intercropped with Natal Sugar than with Carioca. Same row and one row bean cultivar arrangements produced similar maize yields. Land equivalent ratios (LER) were greater than one for all but one intercrop arrangements at CRA but less frequently at DTC. The maize density of 90 x 30 cm with Carioca in the same row as maize produced the highest LER value at all sites, 1.73 at Chinyudze, and 1.53 at Domboshava. The same treatment gave the highest gross return ofZ$12 649 ha-1 at CRA. Carioca planted in the same row as maize at the maize density of 37,000 plants ha-1 is the most ideal approach to dryland maize/bean intercropping since it achieved high yields and allows easy weeding