The effects of dietary glutamine supplementation on growth performance and intestinal morphology of broiler chickens reared under hot conditions

Dietary supplementation effects of 0%, 0.25%, 0.5%, and 1% glutamine were investigated on the performance and development of the gastrointestinal tract in broilers reared under hot conditions. No significant differences were observed between the treatments for feed intake and feed conversion ratio during the starter period, grower period, or entire experiment (P > 0.05). During the grower period, only 0.5% glutamine-fed birds had higher body weight gain than others (P < 0.05). For the entire period, body weight gain of 0.5% glutamine-fed birds was greater than that of 0.00% and 0.25% glutamine-fed ones (P < 0.05). Furthermore, 0.5% glutamine-fed birds showed longer villus height than other birds (P < 0.05). In the jejunum, both 0.5% and 1% glutamine consumption caused longer villus height as compared to 0.00% and 0.25% glutamine (P < 0.05). Villus height of 0.25% glutamine-fed birds was higher than that of 0.00% glutamine-fed ones (P < 0.05). None of the ileum morphological parameters were affected by glutamine supplementation (P > 0.05). In conclusion, supplementation of 0.5% glutamine improved the intestinal morphology and body weight gain of broilers under heat stress. Higher dietary glutamine (1%) increased the villus height in the jejunum but did not change the performance.