The effect of melatonin, its combination with FGA and eCG and OvSynch protocol on the levels of steroid hormone and morphometry of ovaries during oestrus season of ewes

Abstract

The effect of 1) melatonin (MEL) alone; 2) its combination with intravaginal sponges (40 mg FGA) and with 500 IU eCG and 3) OvSynch Protocol on the concentrations of progesterone (P4 ), oestradiol 17β (E2 ) in the blood serum, morphometry of ovaries and population of follicles during physiological oestrus of sheep was studied. Experimental groups 1 (n=6) and 2 (n=5) were administered MEL before the start of oestrus season (5 mg per head/day) for thirty days. After 30 days of MEL administration the intravaginal sponges were instilled to the group 2 for 12 days. After removal of sponges eCG was injected. The ewes of the group 3 (n=11) were treated according to OvSynch. The concentrations of P4 and E2 were determined in the blood serum using the RIA. The ovaries were fixed in 4 % formalin after ovariectomy and consecutively processed by standard histological methods. The results were statistically processed and evaluated by ANOVA. The significant differences were recorded after comparison of the concentrations of P4 (P < 0.05) and E2 (P < 0.01) between group 1 and group 3. The morphometric parameters as well as the representation of follicles population showed improvement, but difference between the experimental groups which was in favour of group 2 was non-significant. Treatment with MEL alone induces the cyclic function of ovaries, but it was not able to synchronize the ovarian processes. Its combination with other environmental methods is more advantageous. OvSynch shows positive oestrus synchronizing effect at taking into consideration species characteristics of the cyclic function of ovaries.