The Effect of Darkness Treatment on Plasma Melatonin Concentrations and Reproductive Performance in Akkaraman Ewes

Abstract Different techniques are used to achieve pregnancy out of season in sheep. These techniques are mostly performed with artificial and natural hormone injections. In this study, darkness application was carried out as a different technique. This study investigates the effect of the darkness treatment on plasma melatonin concentration and reproductive performance during the out-breeding season (April month) in the Akkaraman sheep breed. The vaginal implant device CIDR (0.30 g progesterone) in all sheep was used for return to the beginning of the follicular development (0.day). The control group (C; n = 25) was synchronized by using natural and synthetic hormones. The dark group (D; n = 25) was exposed to darkness for 13 hours (18:00–07:00h) in a fully environmentally controlled shelter. Ewe was taken blood in a specific program, and melatonin hormone concentrations were determined in Elisa device. At the end of darkness application, melatonin hormone concentration in the darkness applied group (90.83 ± 29.27 pg/ml) was higher than the control group (66.58 ± 21.05 pg/ml) (P <0.01). At the end of the experiment, melatonin concentration was higher in the darkness applied group (89.30 ± 29.57 pg/ml) than the control group (54.44 ± 22.97 pg/ml) (P <0.01). Reproductive characteristics were not different between the groups (P>0.05). According to these results, it has been shown that melatonin hormone concentrations may change with the application of darkness during the out-breeding season in sheep, and ıt is possible to estrus synchronize with this method in the Akkaraman sheep breed.