The Effect of Dietary Supplementation of Some Antioxidants on Performance, Oxidative Stress, and Blood Parameters in Broilers under Natural Summer Conditions

The aim of the study was to evaluate the effects of dietary supplementation with some antioxidants (vitamins & minerals) against the deleterious impacts of heat stress on broilers. One hundred and twenty eight broiler chicks were randomly assigned into 4 dietary groups with 4 replicates (8 chicks each). The chicks were raised for 6 weeks under natural summer months (36 °C and 75% RH) during which the birds received either a basal diet only (control group), or the basal diet supplemented with either 250 mg vitamin C+ 250 mg vitamin E/ kg diet, or organic microminerals: 40 mg Zn + 0.30 mg Se/ kg diet, or with 0.50 mg Cr/kg diet. Another group of birds which consists of 32 broiler chicks (4 replicates, 8 birds each) was reared under natural autumn conditions (25 C° and 67% RH) and fed on the same control diet. This group was used to stand out the effects of heat stress per se through comparing its results with those of the previous control one. It was found that high ambient temperature severely reduced body weight, feed intake, and feed efficiency as well as increased abdominal fat and mortality rate. However the supplementation of antioxidants was able to alleviate many of these effects. The heat stress condition significantly increased serum cholesterol, glucose, and malondialdehyde and decreased protein and glutathione peroxidase. Even though, the used supplements improved the blood profile parameters and the oxidative status of birds. The present results indicate that the supplementation of diets with antioxidants, especially vitamins and chromium, is necessary to overcome the deleterious effects of heat stress on broilers’ performance.