Plasma leptin in sheep with single and double ovulation

The experiments were carried out to investigate the levels of leptin and 17 beta -estradiol in the plasma of synchronised PON ewe-lambs and ewes, Thes e hormones were evaluated in order to determine their level in relation to ovulation rate. Laparoscopic examination of the ovaries of all the ewes was performed on the 6th day of the oestrus cycle to determine the number of c orpora lutes per ewe, Ovulation rate in the ewe-lambs was lower both in the group fed on hay as well as the group on mixed feed lower than in the resp ective group of ewes, Plasma samples were collected during standing oestrus every 30 min, for 3 or 6 h and analysed for leptin and estradiol (E-2), Pl asma leptin concentrations during standing oestrus were the lowest in ewe l ambs fed on hay with single ovulation (1.60 +/- 0.46 ng/ml) and the highest in ewes on mixed feed with double ovulation (2.24 +/- 0.12 ng/ml), The opp osite trend was observed in relation to the level of estradiol, Both ewes a nd ewe-lambs with double ovulation had lower levels of E-2 (20.49 +/- 3,94 and 19.44 +/- 0.75 pg/ml respectively) than single ovulated (28.40 +/- 4.28 and 25.24 +/- 1.48 pg/ml respectively), These results suggest that one of the factors determining the ovulation rate in sheep is the level of leptin during oestrus, Because the leptin level remains in an inverse relation to the E-2 level, the action of the leptin may suppress E-2 synthesis and thus promote the development of addition vesicles in sheep ovaries.