Response of fat-tailed Syrian Awassi ewes to accelerated lambing systems |
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Authors: | Moutaz Zarkawi |
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Institution: | (1) Division of Animal Production, Department of Agriculture, Atomic Energy Commission, P. O. Box 6091, Damascus, Syria |
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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. |
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