Effect of free choice feeding as to protein levels on oxidative status in the broilers exposed to heat stress [Si{dotless}cakli{dotless}k stresine maruz broylerlerde protein yönünden seçmeli yemleme uygulamasi{dotless}ni{dotless}n oksidatif strese etkisi]

This study was conducted to evaluate the effects of free choice feeding on oxidative stress in broilers exposed to high temperature. at 21 days of age,24 male ross 308 strain chicks were divided into four groups of six with respect to feed composition and temperature regimen. broilers were evenly divided into two environmental rooms with temperatures set at 22°c (group 1 and 2) and 30°c (group 3 and 4). the experiment consisted of 2 dietary treatments per temperature. half of the birds in each room were feed according to traditional nutrition procedure (group 1 and 3) and the other half were feed according to free choice feeding system (group 2 and 4). for the free choice feeding systems,birds were allowed to choose between diets containing 18% or 23% crude protein. at the end of the 7th week,some oxidant (lipid hydroperoxide,total oxidant status and oxidative stress index) and antioxidant (total antioxidant capacity,total free sulfhydryl groups and ceruloplasmin) in the plasma and performance (feed consumption,body weight gain,feed convertion ratio and average daily protein intake) parameters were measured. high temperature treatment disrupted performance and oxidative status by elevated lipid hydroperoxide level,total oxidant status and oxidative stress index. on the other hand,antioxidant parameters such as total antioxidant capacity and free sulfhydryl level did not decrease,moreover,ceruloplasmin levels increased in response to elevated oxidative stress in broilers exposed to heat stress. as for free choice feeding,it did not affect oxidative status and performance parameters in any of the groups. these results suggest that high temperature treatment increased the oxidative stress in both feeding treatment groups. free choice feeding failed to ameliorate oxidative stress caused by high temperatures in broilers.