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Prolificacy and 50-day lamb weight of ewes in the Cambridge sheep breed

Published online by Cambridge University Press:  02 September 2010

J. B. Owen ,
Sarah R. E. Crees ,
Janet C. Williams  and
D. A. R. Davies
J. B. Owen
Affiliation:
Department of Agriculture, University College of North Wales, Bangor LL57 2UW
Sarah R. E. Crees
Affiliation:
Department of Agriculture, University College of North Wales, Bangor LL57 2UW
Janet C. Williams
Affiliation:
Department of Agriculture, University College of North Wales, Bangor LL57 2UW
D. A. R. Davies
Affiliation:
Department of Animal Husbandry, Veterinary Field Station, University of Liverpool, Leahurst, Neston, South Wirral L64 7TE
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Abstract

The paper describes the results of the analysis of over 3000 records of Cambridge sheep kept on 11 farms over a 12-year period. The heritability of the number of lambs born per ewe increased from a low value for the 1-year-old ewes to a high value for the 3-year-old ewes; the multiple age value for 2-, 3- and 4-year-old ewes was 0·33 (s.e. 0-121). Heritability estimates for number of lambs surviving were lower, but showed the same trend of increasing values with increasing ewe age. This trend in heritability was also evident for the mean 50-day lamb weight, as a trait of the ewe, which had a multiple age value of 0·20 (s.e. 0·151). The estimates of heritability of various measures of early lamb mortality were relatively low. Date of first oestrus showed a variable heritability although the multiple age value was 0·42 (s.e. 0·149).

Prolificacy was strongly correlated with various measures of early lamb mortality although the correlation with the final number of lambs weaned was positive. Prolificacy was positively correlated with the ewe's mature weight and the ewe's date of first oestrus and the genetic correlation with mean 50-day lamb weight was slightly positive.

The effect of increases in prolificacy on numbers of lambs weaned was markedly curvilinear with maximum numbers of lambs weaned at an intermediate level of prolificacy.

Type
Research Article
Information
Animal Production , Volume 42 , Issue 3 , June 1986 , pp. 355 - 363
Copyright
Copyright © British Society of Animal Science 1986

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