The Grain Replacement Value of Processed Cassava in Broiler Finisher Rations

Abstract

EIGHT hundred Starbrow day-old broiler chicks were raised on deep litter on a commercial broiler starter ration. At the end of seven weeks the chicks were randomly and equally alloted to five experimental broiler finisher rations in which maize and gari constituted the main carbohydrate source in the proportions 58:0, 39:16, 29:24.5, 19:33 and 0.49% of ration, respectively. The protein source, groundnut cake, was varied accordingly such that the five rations were isonitrogenous and isocaloric. All other ingredients were mixed in the same amounts for all five rations which were balanced for essential nutrients. All chicks received ad libitum intake of feed and water from the eight week to the thirteenth week when the experiment was concluded. Feed consumption, growth rate, feed efficiency, dressed carcass percentage, liver Weight and abdominal fat percentage were used as parameters to evaluate the relative efficacy of the five ration treatments. 
 Birds on gari rations consumed 3.2% less feed on the average, than those on the Control maize ration, for nearly identical gains. Feed/gain ratio was, therefore, slightly lower for the gari treatments, the lowest value coming from the ration in which maize/gari ratio was 29%:24.5%. Average body weights, rate of gain and feed gain ratio were not significantly different. Variations in carcass and organoleptic measurements indicated no significant differences from dressed carcass percentage, liver weight percentage, tenderness, juiciness, colour or general acceptability. However, abdominal fat percentage was significantly [P<0.001] larger in the gari rations than the control maize ration. This value was highest in the ration that contained only gari as the major carbohydrate source. There was no significant difference in the iodine number of the abdominal fat of the five treatments. 
 The results of this study suggest that gari can replace all the maize in broiler finisher rations or constitute up to 49% of the whole ration, without any decrease in growth rate or carcass quality of broilers, provided such a ration is balanced for protein and amino acids. The best substitution level from this study appears to be at 50%, or 29% of the whole ration.