The feeding value of cassava in commercial poultry diets

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Studies were conducted to determine the effect of cassava inclusion in broiler and layer diets on growth and laying performance, respectively. In the broiler studies, 600 2-week old unsexed chicks from each of four selected farms were randomly allocated to three dietary treatments, namely: T1 — control or the farmer’s own diet, i.e. the normal diet used in the respective farms, T2 — which contained milled cassava mixed with palm oil and T3 - milled cassava with no palm oil. The birds were fed a broiler grower diet from 2 to 6 weeks of age and a finisher diet, 6 to 8 weeks of age. The amount of cassava included in the diets were 150g kg-1 between weeks 3 and 4, 250g kg-1 between 4 and 6 and 300g kg’ during the 7th and 8th weeks. The parameters measured in the broiler trial included mean daily weight gain, mean daily feed intake, feed: gain ratio, feed cost, mortality, and carcass (dressing percentage). Similarly, in the layer feeding trial 720 pullets at the point of lay from each of the four farms were randomly allocated to three dietary treatments as in the broiler trial, with cassava replacing 150g kg-1 diet. Diets were formulated to contain between 160-l70g CP kg and metabolisable energy value of 12.5 MJkg-1. A completely randomised design was used and each treatment was replicated two times on the four farms (E, F, G and H). In the layer trial, the following parameters were studied: feed intake, feed gain ratio, mortality, hen-day production, hen-housed production, egg weight, shell thickness, internal quality of eggs and feed cost. In the broiler feeding trial, birds fed on diets containing cassava with oil and without oil at 250g kg-1 substitution of maize from weeks 4 to 6 registered significantly (P<0.05) lower weight gains compared to those fed on maize diet. Feed efficiency, during 2 to 4 and 4 to 6 weeks of age, by cassava inclusion in the diets of broilers were also significantly (P<0.05) affected by decreasing the conversion efficiency of the broiler birds fed on the cassava based diets. However, the overall feed intake, weight gain and feed efficiency were not significantly (P>0.05) affected by the various dietary treatments. The inclusion of cassava in the broiler diets, significantly (P<0.05) increased the fat pad and also brought about corresponding decrease in the protein content of the broiler meat. Feed costs were lower for cassava-based diets. This represented 9% reduction in broiler feed cost compared with the feed cost of the maize based diet. However, feed costs per kilogram live weight gain were unaffected by dietary treatments. In the laying trial, there was no significant impact on egg production with the inclusion of cassava in diets. The average number of days taken by birds to reach 5% egg production was similar for all experimental birds. Egg quality and feed conversion were unaffected (P>0.05). Feed cost, however, was lower for the cassava-based diets, representing 6.19% and 7.03% savings on feed cost for diets containing cassava plus oil and without oil respectively. Mortality values registered in both the broiler and layer studies were rather variable and showed no trends that could be attributed to the inclusion of cassava in the diet.
A thesis submitted to the Board of Postgraduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirement for the award of Master of Science Degree, 2000