Effect of adding di-ammonium citrate and urea to the diet on performance of broiler chickens under heat stress

This experiment was conducted to investigate effects of blood uric acid on performance and resistance of broilers under heat stress. 200 day old Ross 308 chicks were used in a completely randomized design with 5 treatments, 4 replicates and 10 chicks in each replicate. Chickens were fed from 24 days of age with diets containing 0.35 (U0.35) and 0.70 (U0.70) % of urea and 1.29 (A1.29) and 2.58 (A2.58) % of di-ammonium citrate and without urea or di-ammonium citrate. During the experiment, weight gain, average feed intake and feed conversion were measured weekly. Heat stress was applied with exposing the birds to a 35 ± 1 ˚C temperature from 28 days of age onwards. At 27 and 41 days of age, two birds from each replicate were selected randomly and blood samples were collected from brachial vein to determine the concentration of serum uric acid and malondialdehyde. The results showed that at 36-42 days of experiment, the FCR of A2.58 (1.96) was significantly (P0.05). The content of serum uric acid of U0.7 at 27 and 41 days (2.38 and 6.03 mg/dL respectively) was significantly higher than the control (P