Modulating the Growth Curve in Broiler Chicken through Varying Balanced Protein Regimen (All Step-up, Designed to Get Compensatory Responses)

Abstract

Background: Compensatory growth is a well-established characteristic even in broiler chicken having very short grow-out cycle. Feeding manipulations that take advantages of compensatory growth after a period of nutrient restriction might be beneficial to poultry industry. Methods: In total, 1400 one-day-old straight run broiler chicks (Hubbard) were allocated to 8 experimental treatments, replicated 7 times with 25 chicks in each, in a completely randomized design. The 3 isocaloric corn soybean meal experimental diets; a high BP (HBP) with 1.2% standardized ileal digestible lysine (SID Lys), a medium BP (MBP) with 1.1% SID Lys and a low BP (LBP) 1.0% SID Lys, were offered in starter, grower and finisher phases, as HML (conventional) and LHH, MHH, LMM, MMH, LLM, LLH and LMH as all steps-up. Result: Greater (P less than 0.05) BW and BWG were observed in HML groups during all phases. The MMH group had greater FI (P less than 0.05) during grower and finisher phases. The HML group had better FCR (P less than 0.05) during starter and grower phases. The LMM group had heavier (P less than 0.05) abdominal fat pad, whereas, MHH and HML groups had greater (P less than 0.05) dressed carcass, breast meat, drumstick and thigh yield. The MHH and HML groups, similarly, had higher (P less than 0.05) spleen, thymus, bursa weights, greater antibody titers against NDV and IBDV and total protein concentration. The LLH group had greater (P less than 0.05) blood glucose, urea and total cholesterol concentrations. It is, therefore, recommended that HBP (1.2% SID Lys) should be gradually step down to LBP (1.10% SID Lys) for efficient and sustainable production of broiler chicken.