Dietary chromium-methionine supplementation and broiler (22-43 days) responses during heat stress. 1. Growth performance and carcass yield, metabolisable energy and serum biochemistry

Abstract

Context: Chromium (Cr) is considered a beneficial trace element. It has been reported that supplementation with Cr in the diet promotes improvements in the productive variables of broilers reared under heat stress (HS). Aim: The study aimed to evaluate dose response of Cr as chromium-methionine (CrMet) supplementation on metabolisable energy, serum biochemistry, growth performance and carcass yield of broilers. Methods: Three hundred and thirty-six 22-day-old male broiler chickens were randomly assigned to four blocks, six treatments (0, 0.10, 0.20, 0.40, 0.80 and 1.20 mg/kg dry matter (DM) Cr as CrMet), eight repetitions with seven birds per experimental unit, subjected to HS (33°C for 12h/day) from 22 to 43 days. The supplemented CrMet level for each variable studied was estimated using linear and quadratic regressions. Key results: The bodyweight was quadratically affected at 35 and 43 days (P < 0.01), as well as bodyweight gain (P = 0.02) and feed conversion ratio (P = 0.01) from 22 to 43 days. A linear improvement (P = 0.03) was observed in the feed conversion ratio from 22 to 28 days and bodyweight gain for 22 to 35 days (P = 0.02). The nitrogen-corrected apparent metabolisable energy and the coefficient of metabolisation of energy were quadratically affected (P < 0.01 and P < 0.01, respectively) by CrMet levels in the diet. A quadratic response was observed on total serum cholesterol (P < 0.01), serum glucose (P = 0.07) and triacylglycerol (P < 0.01). The abdominal fat deposition was quadratically affected (P < 0.01) by CrMet levels in the diet. Conclusions: The supplementation of 0.77 mg/kg DM Cr as CrMet improves performance, carcass characteristics and serum biochemistry parameters of broiler chickens reared under heat stress. Implications: The results indicate that CrMet can be supplemented in the diet for broilers reared under heat stress to improve productivity of broiler chickens.