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Components of environmental variance of yields of cows in different lactations

Published online by Cambridge University Press:  02 September 2010

Susan Brotherstone ,
W. G. Hill  and
R. Thompson
Susan Brotherstone
Affiliation:
Institute of Animal Genetics, University of Edinburgh, West Mains Road, Edinburgh EH9 3JN
W. G. Hill
Affiliation:
Institute of Animal Genetics, University of Edinburgh, West Mains Road, Edinburgh EH9 3JN
R. Thompson
Affiliation:
AFRC Institute of Animal Physiology and Genetics Research, Edinburgh Research Station, West Mains Road, Edinburgh EH9 3JQ
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Abstract

With a view to incorporating identifiable environmental factors such as month of calving as random effects in models for dairy sire and cow breeding value estimation, an analysis was undertaken of environmental components of variance for fat yield in lactations 1 to 5 of pedigree British Friesian-Holstein cattle. Records of fat yield and of log fat yield on daughters of widely used sires were first corrected for age and month of calving and for sire in each lactation on a national basis. Variance components for herd-year, herd-year × lactation, herd-year × month of calving, herd-year × month of calving × lactation and error were then estimated for pairs of lactations.

The results were most consistent for log fat yield, where heterogeneity of variance was less. Correlations were, approximately, 0·45 and 0·42 for records in the same herd-year and lactation for lactation 1 or a later lactation, respectively, and approximately 0·40 for records in the same herd-year and different lactations. Within herd-year and lactation, correlations of records in the same month were approximately 0·10 for lactation 1 and 0·08 for later lactations, and for different lactations the correlations were 0·06 if lactation 1 was included and 0·08 otherwise. Thus, the effects appear to be similar for later lactations, which can be pooled, but effects for month and month × lactation 1 v. later should be fitted.

Type
Papers
Information
Animal Production , Volume 48 , Issue 2 , April 1989 , pp. 283 - 291
Copyright
Copyright © British Society of Animal Science 1989

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References

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