Effects of glutamine supplementation on performance, carcass traits, and oxidative stress markers in native crossbred chickens under heat stress conditions

Glutamine is a conditionally essential amino acid known to support energy metabolism, immune function, and antioxidant capacity in poultry. This study aimed to evaluate the effects of dietary glutamine supplementation on growth performance, carcass characteristics, meat quality, and oxidative stress indicators in Pradu Hang dam native crossbred chickens raised in open-sided housing during hot weather conditions. A total of 750 day-old male chicks were allocated to three dietary treatments: control (0% glutamine), 1% glutamine, and 2% glutamine, in a completely randomized design with five replicates per treatment (50 birds/replicate). The trial lasted 12 weeks, from May to July 2024, during which ambient temperature averaged 33.25 °C with relative humidity at 62.5%. Results showed that glutamine supplementation significantly improved final body weight (P = 0.002), average daily gain (P < 0.001), and feed conversion ratio (P = 0.021). Mortality rates decreased in a dose-dependent manner (P < 0.001). Carcass traits such as wing, breast, and drumstick weights were significantly increased (P < 0.05), while meat protein content was higher in the supplemented groups (P < 0.05). Glutamine reduced malondialdehyde (MDA) levels (P < 0.05) and increased glutathione (GSH) and glutathione peroxidase (GPx) activity (P < 0.05), indicating reduced oxidative stress. No significant differences were observed in cortisol levels. The 1% glutamine level was identified as the optimal dose, offering improved performance with minimal increase in feed cost.