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Age at puberty and possibility of early breeding in Awassi ewes

Published online by Cambridge University Press:  27 March 2009

A. A. Younis ,
I. A. El-Gaboory ,
E. A. El-Tawil  and
A. S. El-Shobokshy
A. A. Younis
Affiliation:
Department of Animal Production, College of Agriculture, University of Baghdad, Abu-Ghraib, Iraq
I. A. El-Gaboory
Affiliation:
Department of Animal Production, College of Agriculture, University of Baghdad, Abu-Ghraib, Iraq
E. A. El-Tawil
Affiliation:
Department of Animal Production, College of Agriculture, University of Baghdad, Abu-Ghraib, Iraq
A. S. El-Shobokshy
Affiliation:
Department of Animal Production, Institute of Agricultural Technology, Abu-Ghraib, Iraq
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Summary

Sixty-four weaned Awassi ewe lambs were used in the present study to estimate age at puberty and to investigate whether early breeding from such ewe lambs is possible. After weaning at 4 months old ewe lambs were divided at random into two experimental groups. One group, designated as moderate, was fed to attain 40 kg live weight at 12 months of age, while the other (high) was planned to reach 50 kg at the same age. Fertile rams were run with the ewe lambs at 6 months of age. Twenty ewe lambs, 10 from each treatment, were slaughtered and their ovaries were examined for the presence of corpora lutea and largest follicles.

The overall age at first oestrus was found to be 293 days. Ewe lambs of the high nutritional treatment reached puberty earlier than those of the moderate one (274 v. 312 days). Likewise, single-born lambs reached puberty earlier than twin-born ones (273 v. 312 days). Treatment differences explained 16·5% while type of birth explained 16·3% of the total variance in age at first oestrus. Ewe lambs of the high nutritional treatment experienced more heats than those of the moderate one. Simple correlation coefficients between age at first oestrus and date of birth, daily gain and live weight at puberty were 0·21, 0·09 and 0·75, respectively. Results indicated that ovulation may not occur during the first and second oestrus. From 44 ewe lambs only 12, 10 from the moderate and 2 from the high treatment, lambed 13 viable lambs. Reasons for such a low conception rate (27·3%) are discussed.

Type
Research Article
Information
The Journal of Agricultural Science , Volume 90 , Issue 2 , April 1978 , pp. 255 - 260
Copyright
Copyright © Cambridge University Press 1978

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