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Phenotypic and genetic parameters for reproductive performance in a synthetic line of sheep

Published online by Cambridge University Press:  27 March 2009

T. G. Martin ,
D. Nicholson ,
C. Smith  and
D. I. Sales
T. G. Martin
Affiliation:
A.R.C. Animal Breeding Research Organisation, West Mains Road, Edinburgh EH9 3JQ
D. Nicholson
Affiliation:
A.R.C. Animal Breeding Research Organisation, West Mains Road, Edinburgh EH9 3JQ
C. Smith
Affiliation:
A.R.C. Animal Breeding Research Organisation, West Mains Road, Edinburgh EH9 3JQ
D. I. Sales
Affiliation:
A.R.C. Animal Breeding Research Organisation, West Mains Road, Edinburgh EH9 3JQ
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Summary

Data on 902 ewes (1755 records) bom over 7 years in the synthetic ABRO Dam Line were analysed by least squares. Reproductive traits of the ewe were not affected by whether she was a single or a twin or by the age of her dam. Ewe age had major effects on all reproductive traits. Litter weight traits were affected by the sex distribution and the age of the litter when weighed.

Heritability estimates, both by half sib and regression methods, were low for litter size, low to moderate for litter weights, and higher for ewe and fleece weights. Genetic correlations among the litter-weight traits were high. Together with the heritability estimates, they indicated that selection on litter weight at birth (and perhaps other traits) might give a greater change in total litter weight at weaning, the main measure of ewe productivity and the objective in improvement, than would direct selection.

Type
Research Article
Information
The Journal of Agricultural Science , Volume 96 , Issue 1 , February 1981 , pp. 107 - 113
Copyright
Copyright © Cambridge University Press 1981

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References

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