Energy utilization and growth responses of broiler chickens on vegetable protein diets

Abstract

This study was undertaken to investigate the gross response and energy utilization of broiler chicks fed on vegetable protein or conventional diets. Two hundred and fifty-two day-old Cobb-500 male broiler chicks were randomly assigned to five experimental groups and raised on a control diet (containing tallow) or diets containing fish meal (SBM50 and Can50) or diets with no animal products (SBM75; Can75) (predominantly soybean or canola meal). Birds were reared mainly on litter under similar environmental and management conditions from 1 to 21 days on starter diets. Feed intake was highest (P<0.001) on the SBM50 and Can50 diets, and lowest on the SBM75 diet. Birds in the SBM50 and Can50 diet groups were heavier (P<0.001) than those in other groups, with SBM75 and Can75 diet groups being the lightest. Birds on SBM75 and Can50 achieved superior feed conversion ratio (FCR), while birds on Can75 diet were the poorest. The dietary apparent metabolisable energy (AME) contents were similar, but ME intake on the SBM50 and Can50 diets was higher (P<0.001) than in other groups. Heat production (HP) was similar, but net energy of production (NEp) was improved (P<0.05) in the birds on SBM50 and Can50. Birds on SBM50, Can50 and Control diet groups retained higher (P<0.05) energy as fat (REf), while energy retention as protein (REp) was highest (P<0.05) in the SBM50 and Can50 diet groups. The efficiencies of utilization of ME for energy (KRE), protein (KREp) and fat (KREf) retentions were unaffected. The results demonstrated that birds on the conventional diets (SBM50; Can50) utilized energy better, and grew faster than the birds on vegetable protein (SBM75; Can75) and Control diets.