Investigation of the zinc accumulation in the tissue and performance in broilers raised with high levels of zinc sulfate feed under heat stress

Abstract

The objectives of this study were to evaluate the effects of feeding zinc sulfate on the growth performance, Zn accumulation in the tissue, and the tibia quality. First day old of 100 chicks were randomly assigned to 10 experimental groups in a 5 (0 mg/kg Zn, 40 mg/kg ZnO, 40 mg/kg ZnSO$_{4}$.H$_{2}$O, 500 mg/kg ZnSO$_{}$, and 1000 mg/kg ZnSO$_{4}$) × 2 (high and low temperature) factorial arrangement under randomized complete block design (RCBD). Each experimental group was replicated with 10 birds. Birds were kept in individual cage until 42 days. The results showed that broilers receiving the zinc sulfate supplementation throughout the experiment period (weeks 1 - 6) could improve their average daily feed intake (ADFI) and average daily gain (ADG); however, there were no significant differences in the feed conversion ratio (FCR). Under the high ambient temperature, both zinc oxide (40 mg/kg) and zinc sulfate (40 mg/kg) supplementation improves the FCR throughout the experiment period. Furthermore, during weeks 5-6, supplementation of zinc sulfate with the zinc dose of 1000 mg/kg increased the ADG. Comparing the two levels of temperature showed that broilers kept under a low environmental temperature with a zinc supplementation of 1000 mg/kg experienced more adverse effects than broilers kept under a high environmental temperature. In addition, there were no interactions between the diet and temperature on the zinc accumulation in the meat (breast and thigh), feathers, and organs (liver), as well as tibia length and breaking strength. In conclusion, the zinc supplementation of 40 mg/kg in the diet was a suitable dose for broiler, which were reared under high ambient temperatures for long period.