Effect of different levels of energy and protein with constant ratio on performance and carcass characteristics in broiler chickens

ABSTRACT: The aim of this study was to determine the effect of different levels of energy and protein with constant ratio on performance and carcass characteristics in broiler chickens. Three experimental diets were formulated to have 3 levels of ME and CP, respectively in each phase: 23%, 21% and 20% CP with 3031.6, 2768 and 2636 kcal/kg in the starter phase; 22%, 20% and 19% CP with 3174.3, 2886 and 2742 kcal/kg in the grower phase; and 20%, 18% and 17% CP with 3224, 3063 and 2902 kcal/kg in the finisher phase; The ratio between CP and ME was maintained at 131.8, 144.3 and 161.2 in the starter, grower and finisher respectively. A total of 360 ROSS 308 strain reared for 42 days and were randomly divided into 30 experimental pens, 12 chickens in each pen, and each diet was offered to 10 replicates at random. Wight gain was linearly decreased (p < 0.05), whereas the feed intake and feed conversation ratio were increased (p < /0.05), linearly as dietary protein and energy decreased in grower, finisher and overall experimental periods. Protein efficiency ratio and Energy efficiency ratio were decreased (p < 0/05), when protein and energy reduced in grower, finisher and whole of experimental diets. But Use of different levels of energy and protein with constant ratio on carcass weight (CW), percentage of carcass, breast and thigh and other parameters of carcass such as liver, heart weight and abdominal fat had no significant effect (p > 0.05). Feeding broiler chickens low ME and low CP with ME:CP ratio has adversely affected the growth performance, but carcass parameter not affected without any increase in liver weights and abdominal fat content.