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Oestrous activity of Suffolk, Mutton Merino and their crosses with subtropical Ossimi sheep

Published online by Cambridge University Press:  27 March 2009

A. M. Aboul-Naga ,
M. B. Aboul-Ela  and
F. Hassan
A. M. Aboul-Naga
Affiliation:
Animal Production Research Institute, Ministry of Agriculture, Dokki, Cairo, Egypt and Faculty of Agriculture, University of Mansoura, Egypt
M. B. Aboul-Ela
Affiliation:
Animal Production Research Institute, Ministry of Agriculture, Dokki, Cairo, Egypt and Faculty of Agriculture, University of Mansoura, Egypt
F. Hassan
Affiliation:
Animal Production Research Institute, Ministry of Agriculture, Dokki, Cairo, Egypt and Faculty of Agriculture, University of Mansoura, Egypt
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Summary

Two trials were conducted to study the seasonal variation in oestrous activity over the year in Suffolk (S) or mutton Merino (M) temperate breeds, and their crosses with the local Ossimi (O) sheep under the prevailing subtropical conditions. In the first trial, groups of S, 75% S, 50% S, and O were used and the second trial involved groups of M, ¾M, ½M, ½M and O. The incidence of oestrus was measured by teasing with vasectomized rams. Suffolk ewes had a restricted period of oestrous activity (August–January) whereas M had a longer breeding season (August–March) with high incidence of long and double cycles. Local O showed irregular oestrous activity almost around the year, with particular decline in April. In both trials, all crosses had better oestrous activity than the pure parents, with the 50% S and the ½M having the best performance in the two trials, respectively. The period from September to February seemed to be the period of normal cycling activity in all breed groups, whereas the period from March to May was associated with marked breed-group variation in oestrous activity. Normal cycle length of the S was significantly (P < 0·01) shorter than the local O (16·0 v.17·7 days) and was more consistent than other breed groups. In the two trials, normal cycle length of the cross-breds was ranked between the two purebred parents.

Type
Research Article
Information
The Journal of Agricultural Science , Volume 104 , Issue 1 , February 1985 , pp. 27 - 34
Copyright
Copyright © Cambridge University Press 1985

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