The Effect of melatonin implant on adrenal gland function in Arabian ewe in out of breeding season

The purpose of this study was to investigate the effect of melatonin implant on adrenal function and serum cortisol level in Arabian ewes out of the breeding season. For this purpose، 16 Arabian ewes with 2 to 4 years old (mean weight 35±5 kg) and non-pregnant were divided into two groups. The survey was conducted from late December to early March for 10 weeks. The first group (control) received no melatonin. Implantation of melatonin was used in the second group. Weight of adrenal gland in treatment of melatonin implant in compare with control group is significantly dicrease (p<0. 01). Weight of adrenal gland and thickness of the cortex، capsule، glomerulosa، fasciculate and reticularis in treatment of melatonin implant has been decreased in compare with control group (p<0. 01). In all times of study، there was no significant differences in cortisol levels between melatonin and control treatments (P>0. 05). in control group، the cortisol concentration of blood serum in day 14 was significantly higher than days 42 and 56 (p<0. 01). But in melatonin treatment، there were no significant different in cortisol value among all times of study (P>0. 05). With regard to the results of this study can be said، use of melatonin to induction breeding season in Arabian ewes، not as a stressor and its application in out of the breeding season did not increase the cortisol level.