Dietary glutamine improves meat quality, skeletal muscle antioxidant capacity and glutamine metabolism in broilers under acute heat stress

This study investigated the effects of glutamine (Gln) on meat quality, skeletal muscle antioxidant capacity and Gln metabolism in heat-stressed broilers. Three hundred 42-day-old broilers were randomly divided into five groups: a control group (23 +/- 1 degrees C), which was fed basal diet, and four experimental groups (34 +/- 1 degrees C), supplemented with 0, 5, 10, and 20g Gln/kg of basal diet. The experiment lasted for 24h. Compared with the control group, acute heat stress caused a significant reduction (p<.05) in meat pH, water-holding capacity (WHC), gumminess and hardness, and a significant increase (p<.05) in cooking loss (CL) and lightness (L*) values. However, dietary Gln (20 g/kg) increased (p<.05) meat pH, WHC, gumminess and hardness, but decreased (p<.05) meat CL and L* values in the acute heat-stressed group. In breast and thigh muscles, the acute heat stress group exhibited significantly (p<.05) higher concentrations of malondialdehyde (MDA), but significantly (p<.05) lower levels of Gln, glutamate and glutaminase than the control group; dietary 20 g/kg Gln significantly decreased (p<.05) MDA concentrations, while it increased (p<.05) glutathione, glutathione peroxidas, T-AOC, Gln, glutamate, and glutaminase levels in acute heat-stressed groups. Gln could increase meat quality by improving antioxidative capacity and Gln metabolism in heat-stressed broilers.