VARIABILITY OF NUTRITIVE VALUE OF SHEA NUT (VITELLARIA PARADOXA) MEAL FOR POULTRY

Abstract

Shea nut meal is an agro-industrial by-product obta ined from the processing of the nuts of the shea tree ( Vitellaria paradoxa , Gaertn.) for fat. It is available for use by the poultry feed industry. There is a dearth of information on its n utritive value for poultry. The objective of this study was to evaluate the chemical and nutritive va lue of six samples of Ghanaian shea nut meal, which were produced by either expeller or tradition al method in 2004 and 2005. Ross 308 male broiler chicks were placed in metabolism cages (30 x 30 x 36 cm) singly and fed one of the 17 experimental diets (10 replicates) from 12 to 20 da ys of age. Each shea nut meal sample including defatted sample was substituted at levels of 20 and 40 g kg -1 in a basal diet that was composed of maize, dehulled soya bean meal, fishmea l and wheat feed. During the last 4 days, the amounts of feed eaten and droppings voided were recorded. Samples of the shea nut meal, diets, and droppings were analysed for their nutrie nt and gross energy contents using AOAC (2000) methods. There was no significant difference (P>0.05) in the dry matter contents of the samples, which ranged between 907.6 and 946.2 g kg -1 . The mean ether extract (EE) of the expeller samples (145.0 g kg -1 DM) was lower (P<0.01) than that of traditionally-e xtracted samples (379.0 g kg -1 DM) due to efficiency of fat extraction. The free f atty acid content of the residual fat in the samples was lower (P<0.05) in t he expeller samples (89.0 g kg -1 EE) than the traditionally-extracted samples (364.0 g kg -1 EE). The mean crude protein level of the traditionally-extracted samples (110.8) was lower ( P<0.05) than that of expeller samples (134.5g kg -1 DM). There were significant differences in the leve ls of the mean lysine (P<0.05), methionine+cystine (P<0.01) and tryptophan (P<0.05) , which were 40.1 versus 33.1, 39.1 versus 34.3, and 14.1 versus 13.2 g kg -1 CP in the expeller and traditionally-extracted samp les respectively. However, there was a strong and consi stent relationship between the crude protein level and lysine (r 2 =0.8825), methionine+cystine (r 2 = 0.9728) and tryptophan (r 2 = 0.8322) in the samples. Mean total dietary fibre in the expeller s amples (445.4 g/kg DM) was lower (P<0.05) than that of traditionally-extracted samples (507.5 g/kg DM). Mean gross energy content of the expeller samples (23.7 MJ/kg DM) was lower (P=0.01) than that of traditionally-extracted samples (26.7 MJ/kg DM). No significant differences (P>0.05) were observed in mean digestibility coefficients of expeller and traditio nally-extracted samples in terms of dry matter (0.645 vs 0.638), crude protein (0.584 vs 0.582) an d crude fat (0.664 vs 0.660), but differed (P<0.05) in gross energy utilisation (0.668 vs 0.66 4). The defatted samples gave similar nutrient digestibility as their corresponding intact samples . The variation observed among samples strongly indicates that industrial source of shea n ut meal should be preferred, but requires improvement for use in poultry rations.