Dietary glutamine supplementation improves growth performance, meat quality and colour stability of broilers under heat stress.

1. The present study was conducted to investigate the effects of dietary glutamine (Gln) supplementation on growth performance, carcase characteristics and meat quality in broilers exposed to high ambient temperature. 2. A total of 240 35-d-old male Arbor Acres broilers were randomly assigned to 4 treatment groups (three replicates of 20 birds per cage). The broilers were kept in a temperature-controlled room at either 23 degrees C (no-stress groups, NS) or 28 degrees C (heat stress groups, HS). The broilers were fed either on a basal diet (control, NS) or on the basal diet supplemented with 0, 0.5 or 1.0% Gln (HS). 3. Compared with the NS, the HS (0% Gln) group gained less weight and consumed less feed, had lower final body weight, gain-to-feed ratio, and abdominal fat yield. Breast meat in HS (0% Gln) had lower pH, water-holding capacity (WHC), a* value, ether extract (EE) content and crude protein (CP) content, and had higher shear force (SF) and L* value. 4. Linear increase were found in groups supplemented with Gln (0, 0.5% and 1.0%) for final body weight, weight gain, feed consumption, gain-to-feed ratio and abdominal fat yield. Supplementation with Gln improved breast meat pH, WHC, SF, L* value, a* value, EE content and CP content in broilers exposed to heat stress. No significant difference was observed in all the indices determined between the HS (1% Gln) and the NS. 5. Heat stress caused obvious breast meat discoloration in L*, a* and b* values. However, dietary supplementation with Gln gave a better colour stability. 6. The results indicated that dietary supplementation with Gln may alleviate heat stress-caused deterioration in growth performance, carcase characteristics, meat quality and meat colour stability of broilers.