Influence of diet and management system on growth and carcass characteristics of Ugandan local chickens
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The effect of feeding regime and management system on growth performance and carcass characteristics of local chicken cockerels was assessed using two experiments. In the first experiment, cockerels were assigned to six dietary treatments in a 2x3 factorial arrangement with two protein levels (18 and 20% CP) and three energy levels (2800, 2900 and 3000kcal/kg ME). Each treatment comprised of three replicates with ten birds each. The birds were reared in a deep litter house. Feed and water were provided ad libitum. In the second experiment, cockerels were randomly allotted to three management systems (deep litter, run and free range systems). Each system was replicated six times with ten birds each. In all the management systems, birds accessed a diet of 20% CP and 3032kcal/kg ME. In both experiments, birds were individually weighed after every two weeks. At the end of each experiment, four cockerels from each replicate were randomly selected and slaughtered. Dressing percentage, cold carcass weight, relative weights of carcass portions and organs; and physical, chemical and organoleptic properties of meat were assessed. Body weight gain, feed intake, feed conversion ratio and energy efficiency of cockerels were not significantly (P>0.05) affected by the dietary regimes. However, at the 2800 kcal/kg ME energy level, an increase in CP from 18% to 20% resulted in a significant decline (P<0.05) in body weight gain. An increase in dietary energy from 2800 kcal/kg to 3000kcal/kg did not significantly affect weight gain. Varying dietary energy and protein had no significant effect (P>0.05) on carcass yield, slaughter characteristics and physical characteristics of meat. Birds reared under the free range system had the lowest body weight gain (P<0.05), whereas those reared under the run and deep litter systems showed similar body weight gains. Birds in the deep litter system had the heaviest breasts (P<0.05), while birds reared in the free range system developed heavier thighs (P<0.05). Management system neither had any significant effect on the physical characteristics of the meat nor on sensory evaluation of breast meat. Birds from the free range system had the least tender and least juicy drumstick meat. The data suggests that the 2800 kcal/kg ME and 18% CP diet was sufficient for intensively reared young Ugandan local chicken cockerels. Cockerels reared under the free range system require more time to attain market weight and their meat possesses attributes that are concomitant with tastes and preferences of many chicken consumers in Uganda.