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Heterogeneity of variance between herds for milk production traits

Published online by Cambridge University Press:  24 November 2017

P.M. Visscher
P.M. Visscher*
Affiliation:
Institute of Cell, Animal and Population Biology, University of Edinburgh, West Mains Road, Edinburgh
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One assumption made by most users of the BLUP (Best Linear Unbiased Prediction) method to predict breeding values, is that variances are homogeneous over herds or herd-year-seasons (HYS). In dairy cattle there is abundant evidence, however, of heterogeneity of variance across herds or herd groups (see e.g. Hill et al. 1983 and Brotherstone and Hill, 1986, for U.K. studies). The effect of ignoring heterogenous variances between herds on prediction of breeding values for bulls may be small when using a sire model, if sires were tested across many herd-variance groups. Loss in efficiency may be larger when sires are tested in few herds, or, for cows, when the genetic evaluation is for bulls and cows simultaneously (with an animal model (AM)). The aim of this study was to calculate individual herd parameter estimates to investigate heterogeneity of within herd variance in the U.K. dairy population. The investigated trait was fat yield and the estimations were carried out using a REML (Restricted Maximum Likelihood; Patterson and Thompson, 1971) program written by Karin Meyer (Meyer, 1989).

Type
Sheep and cattle breeding
Information
Proceedings of the British Society of Animal Production (1972) , Volume 1991 , March 1991 , pp. 28
Copyright
Copyright © The British Society of Animal Production 1991

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References

Boldman, K.G. and Freeman, A.E. (1988). Estimates of genetic and environmental variances of fint and later lactations at different production levels. J. Dairy Sci. 71 (suppl. 2):81–82 CrossRefGoogle Scholar
Brothentone, S. and Hill, W.G. (1986). Heterogeneity of variance amongst herds for milk production. Anim. Prod. 42:297–303 Google Scholar
Gianola, D. (1986). On selection criteria and estimation of parameten when the variance is heterogeneous. Theor. Appl. Genet. 72:671–677 Google Scholar
Hill, W.G., Edwards, M.R., Ahmed, M.-K.A. and Thompson, R. (1983). Heritability of milk yield and composition at different levels and variability of production. Anim. Prod. 36:59–68 Google Scholar
Lofgren, D.L, Vinson, W.E., Pearson, R.E. and Powell, R.L. (1985). Heritability of milk yield at different herd means and variances for production. J. Dairy Sci. 68:2737–2739 CrossRefGoogle Scholar
Meyer, K. (1987). Estimates of variance due to sire*herd interaction and environmental covariances between paternal half-sibs for first lactation dairy production. Livest. Prod. Sci. 17:95–115 Google Scholar
Meyer, K. (1989). Restricted maximum likelihood to estimate variance components for animal models with several random effects using a derivative-free algorithm. Genet. Sel. Evol. 21:317–340 Google Scholar
Mood, A.M., Graybill, F.A., and Boes, D.C. (1973). Introduction to the theory of statistics. McGraw-Hill, New York.Google Scholar
Patterson, H.D. and Thompson, R. 1971. Recovery of inter block-information when block sizes are unequal Biometrika 58:545–554.Google Scholar