A survey of biochemical serom profile of broiler chickens influenced by melatonin supplementation, increasing of dark period on their adaptation to heat stress

Heat stress is very important in poultry production.
To evaluate the effect of oral elatonin supplementation and increasing of dark period on biochemical profile of broiler chickens under Heat Stress (HS).
ETHODS: A total of 200 day- old broiler (Arian) chicks were randomly allocated in to 4 groups (dark ,melatonin, negative and ositive controls). Melatonin group received 40 mg melatonin/kg diet from 30-40 days of age and chickens of dark group were xposed to a special lighting schedule from 10-40 days of age. All groups (except negative control) were daily exposed to HS (39± 1 c) for 6 hours per day from 35-40 days of age. At the end of 6 weeks, body weight was measured. At 30, 35, and 40 days, serum uric acid, glucose, total protein, albumin, globulin, activity of AST and creatinine were measured. ata was analyzed by ANOVA and Tukey test in SPSS software.
In 30 days, there was no significant difference etween groups. In the day 35, only serum uric acid of melatonin group was significantly increased in comparison with egative control. Also, serum uric acid of melatonin group increased significantly in 40 days in comparison with other roups, as melatonin plays an important role in the antioxidant defense system and uric acid is an important antioxidant in chickens. Serum glucose of positive control compared to other groups significantly increased in 40 days. Other biochemical parameters were not significant. In this study,the mean body weight of dark group was significantly decreased. The percentage of mortality rate in negative control, dark, melatonin and positive control treatments was zero, 4 ,5 and 10% respectively.
These results demonstrate that dark period and oral melatonin supplementation can decrease HS.