Zinc-l-selenomethionine in diets of broiler chickens subjected to cyclic heat stress

Abstract Limited information exists on the effects of zinc-l-selenomethionine (Zn-L-SeMet) in broiler diets under cyclic heat stress. Hence, this study aimed to investigate its impact on broiler diets from 1 to 42 days of age reared under cyclic heat stress. A total of 1,000 male Cobb 500® broiler chicks were assigned to five treatments: 0, 0.15, 0.23, 0.47 and 1.30 mg/kg of Zn-L-SeMet. Each treatment consisted of 10 replicates with 20 birds each. Animals fed diets with 1.30 mg had reduced feed intake (FI) compared to the other treatments (p < 0.05) and lower feed conversion ratio (FCR) compared to animals that were fed 0.15, 0.47 mg, and control diets (p < 0.05). Both FI and FCR reduced linearly. Mortality was lower in broilers that were fed diets with 0.15 mg compared to the control (p < 0.05) diet. The inclusion of 0.71 mg was estimated to reduce bird mortality. Broilers fed diets with 0.47 mg had higher triglyceride (TRG) levels (p < 0.05) than those fed with 0.15, 0.23, and 1.30 mg diets. The inclusion of 0.97 mg was predicted to increase TRG levels. Broilers fed diets with 0.47 mg had reduced gamaglutamiltransferase (GGT) levels than those fed with the control diet. In addition, the inclusion of 1.19 mg was predicted to reduce GGT levels. There was no effect of the diets on insulin-like growth factor 1 and growth hormone receptor hormones gene expression. In conclusion, the inclusion of 1.30 mg/kg of Zn-L-SeMet in heat-stressed broiler diets is recommended to achieve the best growth performance from 1 to 42 days of age.