Effect of oestrus synchronization with different lengths of progesterone-impregnated sponges and equine chorionic gonadotropin on reproductive efficiency in Romanov ewes during the non-breeding season

This study aimed to determine the effects of different lengths progesterone and equine chorionic gonadotropin (eCG) treatment on reproductive performance during non-breeding season in ewes. Progesterone-impregnated sponges were inserted intravaginally for 7 d Group 1 (G1, n = 24), 9 2 (G2, 25), 11 3 (G3, 24). On day sponge removal, eCG (350 IU) was injected 24 h later ewes exposed rams. Pregnancy diagnosed by transrectal ultrasonography 30 ± after mating. Oestrus symptoms G2 G3 started earlier than G1, but there only a significant difference between G1 ( P 0.013). In G2, G3, oestrus responses 100%, 95.8%, pregnancy rates 79.2%, 72%, 75%, lambing 79.8%, litter sizes 2.5, 2.2, 2.4, multiple birth 86.7%, 80%, 85.7%, respectively > 0.05). conclusion, short-term progesterone-impregnated provided excellent induction. The days (7, 9, or 11) indicators similar; therefore, stress caused can be reduced use.