Influence of dietary vitamin E and zinc on performance, oxidative stability and some blood measures of broiler chickens reared under heat stress (35 °C)

This study was conducted to determine the effects of vitamin E (αTA; dL-α-Tocopheryl acetate) and zinc (Zn; ZnCl2) on performance, oxidative stability and some blood measures of broiler chickens under normal and hot temperatures. One hundred sixty 10-day-old male chicks were assigned to four groups in four replicates. The birds received two diets, control and enriched with two levels of vitamin E and Zn (100 and 50 mg/kg of diet, respectively) under two ambient temperatures (22 °C and 35 °C). Although the diets enriched with the antioxidant vitamin and element compared with un-enriched diets resulted in the better performance of the birds, significant differences were related to temperature conditions, as the lowest feed conversion ratio (FCR) and the highest body weight (BW) were observed in the group fed the enriched diet under normal temperature. The serum malondialdehyde (MDA), cholesterol (C), triglycerides (TG), glucose (G), total protein (TP), and hematocrit and heterophil: lymphocyte ratio levels were significantly lower in birds reared under 22 °C compared with the group under 35 °C but the hematocrit was not significantly lower in groups fed enriched diets and exposed to normal conditions (P>0.05). It was concluded that a combination of 100 mg of vitamin E and 50 mg of Zn provides the better performance and the least blood C and TG levels accompanying the better oxidative stability in male broilers under normal temperature (22 °C) and that this combination can be considered as a protective strategy in broiler diets for reducing the negative effects of heat stress.