Resumption of postpartum ovarian cyclicity in winter-lambing Lohi sheep (Ovis aries)

Abstract

The postpartum ovarian cyclicity which is associated with uterine involution has significant importance in fertility of sheep. The study was conducted to estimate the postpartum resumption of ovarian cyclicity in Lohi sheep during winter lambing season. Twelve pregnant ewes were selected. The commencement of ovarian cyclicity was investigated in postpartum ewes by estimating progesterone (P₄) concentration in blood samples collected on weekly intervals starting from day of parturition till 12^th week of postpartum. On the day of parturition, mean P₄ concentration was 0.38 ± 0.08 ng / mL. After that, P₄ level raised to 0.70 ± 0.13 and 0.83 ± 0.13 ng / mL during 1^st and 2^nd weeks respectively. During 3^rd week, P₄ concentration was 1.02 ± 0.18 ng / mL (ovulation). The peak P₄ level during first estrous cycle was 3.02 ± 0.8 ng / mL and detected on 5^th week. Second ovulation was observed during 6^th week and again peak P₄ concentration of 2^nd cycle was found as 2.5 ± 0.64 ng / mL on 7^th week. Based upon the hormonal profile, it was concluded that postpartum ovarian cyclicity resumed on 3^rd week of postpartum in winter lambed Lohi sheep.