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Selection and response within the nucleus of a sheep group-breeding scheme

Published online by Cambridge University Press:  02 September 2010

S. Anderson  and
M. K. Curran
S. Anderson
Affiliation:
Wye College, Ashford, Kent TN25 5AH
M. K. Curran
Affiliation:
Wye College, Ashford, Kent TN25 5AH
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Abstract

An evaluation of the response to selection for prolificacy within a nucleus sheep flock of a commercial group-breeding scheme is presented. In 1979, the Romney Group Breeders formed a nucleus flock of 120 prolific ewes chosen from 12 contributing flocks. A control flock was established in 1982 from the same source. The analysis was conducted on the trait of litter size. Selection differentials are presented for each year of birth progeny group in both flocks. Expected selection response was calculated from selection differentials and was found to have an average value of 1·5% of parent mean litter size per year. Using least squares procedures the litter size performance of control and nucleus ewes of 2, 3 and 4 years of age was corrected for environmental effects. Realized response was estimated from the differences between corrected litter size means of control and nucleus flocks. Response in litter size was found to be significant within years and within ewe age groups (P < 0·05).

Keywords

breeding programmeslitter sizeselectionssheep
Type
Research Article
Information
Animal Production , Volume 51 , Issue 3 , December 1990 , pp. 593 - 599
Copyright
Copyright © British Society of Animal Science 1990

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References

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