Abstract:

This study was conducted to determine the effect of progestin source on some reproductive performance, lamb birth weight and lamb mortality rate in Akkaraman ewes. A total of 40 Akkaraman sheep breed with similar body weight (51.3 ± 1.5 kg) and at least two parturitions were used as experimental animals. In all ewes, the intramuscular injection of PGF2α (2.5 mg) was administered 96 hours before estrus synchronization to obtain corpus luteum regression. The ewes were allocated randomly into two groups according to body weight and ages. Estrus of ewes in the first group (n=20) were synchronized with an intra-vaginal CIDR device containing 0.30 g of natural progesterone. Estrus of ewes in the second group (n=20) were synchronized with an intra-vaginal sponge containing 30 mg flugestone acetate (FGA). CIDR and sponge were withdrawn following 12 days and 600 IU PMSG were injected intramuscularly. After 24 hours from injections, all ewes were introduced to Akkaraman rams and ewes in estrus were recorded. There were no significant differences between natural and synthetic progesterone applications in terms of estrus rate, gestation rate and duration of gestation in Akkaraman ewes. Additionally, lamb birth weight and lamb mortality rates were similar in both experimental groups. However, the application of CIDR increased the total and multiple lamb birth rates of Akkaraman ewes (P<0.05). These results show that the application of CIDR device with PMSG may increase the success rate in lamb production in Akkaraman ewes.

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