BACKGROUND: Dietary chromium (Cr3+) supplementation reduces stress in livestock by lowering circulatory cortisol and potentiating the action of insulin. This study aimed to assess the stress-alleviating effects of supplemental Cr3+ as chromium picolinate in broilers.
RESULTS: The birds, which were heat stressed and had restricted feed intake between 31 and 40 days of age, were supplemented with 0 (control), 0.5 or 1 mg Cr3+ kg−1 diet from 10 to 40 days of age. Live weight gain, feed efficiency, utilisation efficiency of energy and protein and conversion efficiency of feed protein to muscle protein improved owing to Cr3+ supplementation (P < 0.05), especially during the period of feed restriction. Cr3+ supplementation increased hot and eviscerated carcass weights and breast weight (P < 0.05) and reduced ether extract content (P = 0.02, linear effect). Meat protein accretion improved owing to Cr3+ supplementation (P = 0.006, quadratic effect). Relative to its pre-supplementation value, serum cortisol increased by 2.3% in the control group and decreased by 7.6 and 14.3% in the 0.5 and 1 mg Cr3+-supplemented birds respectively (age × diet interaction P = 0.0001).
CONCLUSION: It was concluded that supplemental Cr3+ may ameliorate heat stress and augment growth in broilers during periods of physical feed restriction. However, increasing the inclusion of Cr3+ beyond the dose level of 0.5 mg kg−1 diet may not be substantially beneficial. Copyright © 2007 Society of Chemical Industry