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Rebreeding activity in milking Awassi ewes under semi-arid conditions

Published online by Cambridge University Press:  02 September 2010

R. Kassem ,
J. B. Owen  and
I. Fadel
R. Kassem
Affiliation:
Kraim Centre for Sheep Breeding and Range Development, Salamieh, Syria
J. B. Owen
Affiliation:
Centre for Arid Zone Studies, School of Agricultural and Forest Sciences, University of Wales, Deiniol Road, Bangor LL57 2UW
I. Fadel
Affiliation:
Kraim Centre for Sheep Breeding and Range Development, Salamieh, Syria
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Abstract

Post-partum interval to oestrus and conception was studied in relation to previous and current lactation (milk yield and lactation length), age of ewe and treatment with intravaginal sponges in a total of 186 Awassi ewes lambing in December/January. In the first trial, 62% of ewes, tested for oestrus twice a day with vasectomized rams until the end of May, showed oestrus between 1 and 170 days after lambing with a mean interval of 83 (s.d. 31·9) days. Neither current nor previous lactation had important effects on the rebreeding interval (P > 0·05). In another trial where ewes were exposed continuously to fertile rams until the end of March, 50% showed oestrus with a mean interval of 56 (s.d. 23·7) days (range 33 to 113 days). Of those showing oestrus, 86% conceived with a mean post-partum interval of 70 (s.d. 33·0) days (range 33 to 133 days). Lactation yield had no significant effect on the lambing-to-oestrus interval (P > 0·05) but ewes with longer lactations showed longer lambing-to-conception intervals (P > 0·01). Treatment with progesterone-impregnated vaginal sponges at 1, 2 and 3 months post partum showed an increase in the percentage of ewes showing oestrus from 35% to 75% and in those conceiving from 25% to 70% as the timing of treatment increased from 1 to 3 months post partum. It is concluded that lambing three times in 2 years is biologically feasible and that hormone treatment can facilitate its operation in practice.

Type
Research Article
Information
Animal Production , Volume 49 , Issue 1 , August 1989 , pp. 89 - 93
Copyright
Copyright © British Society of Animal Science 1989

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References

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