title: Response of fat-tailed Syrian Awassi ewes to accelerated lambing systems.
abstract: Fifty cyclic fat-tailed Syrian Awassi ewes aged 2-4 years, with a mean weight of 51.4 kg, were used for 4 years to assess the accelerated lambing system (three lambings in 2 years). Ewes were divided into two groups: treated (T) and untreated (C). Ewes in the T group were treated with flugestone acetate for 14 days and injected intramuscularly at sponge withdrawal with 500 IU of equine chorionic gonadotropin (eCG). Results indicated that ewes in the T group exhibited oestrus and were mated within 5 days post sponge removal compared to 11 days for ewes in the C group, and the difference in oestrus response between the two groups was significant (P < 0.001). Repeated hormonal treatments had no significant (P > 0.05) effect on the lamb birth weight. However, significant (P < 0.001) differences in the lamb birth weight were observed between singles and multiple births. In the treated ewes, the total number of lambs born was 211-157 parturitions, and the multiple birth rate reached 27.4%, whereas the rate in the untreated group was 6.3% with the difference being significant (P < 0.05). In the untreated ewes, the total number of lambs born was 14-13 parturitions (12 singles and 1 twin). Fecundity rates were 135.1% and 106.3% in the treated and untreated ewes, respectively, and the difference was significant (P < 0.05). Repeated administration of eCG had no negative effect on fertility of Syrian Awassi ewes. However, anti-eCG antibodies were produced following eCG injections with extremely high individual differences in the immune response among ewes.
authors.affiliation: Division of Animal Production, Department of Agriculture, Atomic Energy Commission, P. O. Box 6091, Damascus, Syria. ascientific1@aec.org.sy
authors.forename: Moutaz
authors.initials: M
authors.lastname: Zarkawi
mesh_terms: D000818:Animals; D001724:Birth Weight / Q000187:drug effects; D001947:Breeding / Q000379:methods*; D006063:Chorionic Gonadotropin / Q000008:administration & dosage; D004971:Estrus / Q000187:drug effects*; D005260:Female; D003425:Flurogestone Acetate / Q000008:administration & dosage / Q000494:pharmacology*; D036801:Parturition / Q000187:drug effects; D011374:Progesterone / Q000097:blood; D012099:Reproductive Techniques / Q000662:veterinary*; D034561:Sheep, Domestic / Q000502:physiology*; D013593:Syria
chemical_list: D006063:Chorionic Gonadotropin; D011374:Progesterone; D003425:Flurogestone Acetate