Short communication. Dietary supplementation effects of zinc acetate and magnesium sulfate on performance and antioxidant status of broilers under continuous heat stress

Abstract

The aim of this study was to investigate the effects of different dietary levels of zinc acetate (Zn; 0, 30 and 60 mg kg-1) and of magnesium sulphate (Mg; 0, 300 and 600 mg kg-1) on performance and blood antioxidant status of broilers under continuous heat stress. For this purpose, four hundred and fifty one-day-old male chicks were used in a 3 × 3 factorial experiment from day 1 to day 42 of age. The inclusion of 30 mg Zn kg-1 increased the body weight gain and the average feed intake and declined the feed conversion ratio (FCR). Although there were no differences between the treatments for FCR, the supplementation with 30 and 60 mg Zn kg-1 decreased the FCR regardless the Mg level. The dietary supplementation with 30 mg Zn kg-1 decreased both blood glutathione peroxidase and superoxide dismutase activities regardless the Mg level. In addition, neither Zn nor Mg influenced the blood total antioxidant capacity content at the end of the experiment. Blood malondialdehyde (MDA) decreased as dietary Zn supplementation increased. The MDA reduction when diet was supplemented with Zn was not obvious at higher Mg level (interaction Zn × Mg, p<0.05). In conclusion, dietary addition of Mg does not significantly influence either the performance or the antioxidant status of broiler at 42 d of age under heat stress but supplementation of 30 mg Zn kg-1 decrease the blood MDA concentration and improves the performance.