BACKGROUND: This study was conducted to evaluate the effect of melatonin on semen quality and quantity changes and increase of reproductive efficiency in Lori-Bakhtiari ram in the non-reproductive season. OBJECTIVES: The purpose of this study was to investigate the effect of melatonin on testicular size and semen qualitative and quantitative changes in the non-breeding season is Lori-Bakhtiari rams. METHODS: This study was designed to evaluate the effects of melatonin on the quantity and quality of semen and testicular diameter in 8 Lori- Bakhtiari rams (4 control rams and 4 treatment rams) for 10 weeks during spring 2013. Each ram in the treatment group was received three tablets of 18 mg implantable melatonin subcutaneously at the base of ear after 5 weeks from the start of the trial. RESULTS: Semen parameters and testicular diameter measurements were evaluated on a weekly basis. No significant differences were observed between 2 groups before melatonin implanting. A significant difference was observed after melatonin implanting between 2 groups in the mean of testicular diameter (treatment: 33.5±0.25 and control: 30.67±0.07 cm), in semen volume (treatment: 1.34±0.03 and control: 0.87± 0.04 ml) and in sperm concentration (treatment: 1.76±0.05 and control: 1.37±0.04 109/ml) (p<0.05). However, other parameters including average of lives sperm percentage, total sperm motility, sperm progressive movement and percentage of abnormal sperm were not significant (p>0.05). CONCLUSIONS: The results of this experiment showed that the use of melatonin in the non-reproductive season resulted in increase of testicular size, semen volume and sperm concentration in Lori-Bakhtiari ram. However, the rest of the semen parameters have not been affected.

BACKGROUND: Heat stress is very important in poultry production. OBJECTIVES: To evaluate the effect of oral elatoninsupplementation 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.  atawas analyzed by ANOVA and Tukey test in SPSS software. RESULTS: 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 inchickens. 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. CONCLUSIONS: These results demonstrate that  dark period and oral melatonin supplementation  candecrease HS.