Impact of Reducing Finishing Feed Energy-Protein Level on Performance, Carcass Yield, and Grade of Broiler Chickens

Broiler chickens reared sex separate received finishing feeds that differed in energy-protein level from 34 to 53 days of age. Control rations (ca. 3200 kcal ME/kg) based on corn, soybean meal, and fat contained ca. 20 and 16% protein for the male and female, respectively. Treatments involved a 5 and 10% reduction of energy with protein from controls. Dietary components were changed so that amino acid availability and balance were constant, fat decreased, and fiber increased. Final body weight and feed efficiency decreased with energy-protein reduction. Carcass processing that emphasized abdominal fat removal led to yields that were improve d by a 5% nutrient decrease. The 10% energy-protein reduction led to a poorer yield with the male as compared to that obtained with the 5% level, while females exhibited no change. A lower finish grade was the only carcass feature altered by reducing finisher energy-protein level. Live weight and carcass changes could be accounted for more in terms of depot fat than in edible component.