Pure glycerin supplementation by drinking water for broilers under heat stress and feed restriction

Glycerol is an energy-rich substance with an osmotic effect in the body, which can assist in the performance of birds subjected to high environmental temperatures. An experiment was conducted to study the effect of pure glycerin supplementation by drinking water for broilers subjected to heat stress and dietary restrictions. The water with 0%, 1%, or 2% glycerin levels was provided ad libitum. The feed was restricted for six hours daily. The experimental period was seven days. A total of 240 male broilers, Cobb lineage were used, aged 35 days and starting weight of 2158 ? 69 g. The birds were housed in two environments: thermoneutral (TN, 25?C), and cyclic heat stress (HS, environmental temperature varied during the day: 12h of 25?C, followed by 6h of 32?C, 3h of 25? to 32?C, and 3h of 32? to 25?C). The experimental design was randomized in a factorial arrangement of 2 x 3 + 2, with three GLIC levels, two environments and one control group fed ad libitum in each environment. Broilers receiving 2% of glycerin in HS increased (p < 0.05) weight gain (WG,) water consumption (WCg), feed intake (FI) and energy consumption (ECn). However, glycerin increments decreased (p < 0.05) those responses in TN environment. Feed restriction, regardless of glycerin levels, decreased FI (p < 0.05) but improved feed conversion ratio (p < 0.05) compared to control group in each environment. Restricted broilers receiving 2% of glycerin in HS showed higher WCg (p < 0.05) and similar WG compared to control. However, in the TN environment, restricted bird receiving 2% of glycerin showed lower (p < 0.05) WCg and WG than the control. The use of 2% pure glycerin, by drinking water, can compensate the drop in performance caused by feed restriction management in broilers subjected to heat stress.