Effects of β-glucan on the performance and gut integrity of broilers under acute heat stress conditions.

Heat stress (HS) has negative impacts on farm animals. Many studies have been conducted to ameliorate the effects of HS in farm animals. The current project investigated the effects of β-glucan (BG) supplementation under thermo-neutral and HS conditions on the production, physiological, and histological parameters in broiler chickens. Three-hundred and twenty chicks were randomly assigned into four treatments (10 replicates/treatment; 8 chicks/replicate). The treatments were: 1) a basal diet (Ctrl); 2) a diet containing 1 g/kg of β-glucan (BG1); 3) a diet containing 2 g/kg of β-glucan (BG2); 4) a diet containing 3 g/kg of β-glucan (BG3). All treatments were reared under thermo-neutral (TN) conditions from day 0-30 days of age then exposed to cyclical HS at the age of 31 days for 3 consecutive days (4 hours/day). During HS conditions, BG3 has increased feed intake (FI; 23 %; P < 0.01), and decreased rectal temperature (Tr) relative to the control treatment (0.5 °C; P <0.01). Besides, supplementing BG has improved average daily gain under HS conditions. In addition, BG supplementation had a positive effect on intestinal morphometric parameters (villous height, width, depth, and surface area) under HS conditions. In conclusion, feeding BG improved FI, average daily gain (ADG), and intestinal health in heat-stressed broiler chickens.