This paper is only available as a PDF. To read, Please Download here.
Abstract
The detection of heterogeneous variance across herd groups is based largely on data stratified by mean herd production. Such stratification is analogous to selection on herd means. This introduces the possibility of biased estimates of genetic and residual variances. Results presented show that Henderson's Method 3 estimates of the residual variance are unbiased by selection on herd means. However, reductions in sums of squares for sires have different expected values in no selection and selection models. The magnitude of this bias is evaluated with a small-scale simulation. Extension of these results to other methods of variance estimation reveals a potential bias from selection on herd means.
References
- Genetic parameters for first lactation milk yields at three levels of herd production.J. Dairy Sci. 1987; 70: 1434
- The problem of heterogeneous within herd error variance when identifying elite cows.J. Dairy Sci. 1982; 65 (Abstr.): 100
- On selection criteria and estimation of parameters when the variance is heterogenous.Theor. Appl. Genet. 1986; 72: 671
- Estimation of variance and covariance components.Biometrics. 1953; 9: 226
- Best linear unbiased estimation and prediction under a selection model.Biometrics. 1975; 31: 423
- Heritability of milk yield and composition of different levels and variability of production.Anim. Prod. 1983; 36: 59
- Heritability of milk yield at different levels of herd mean and standard deviation for production.J. Dairy Sci. 1985; 68: 2737
- Trends in genetic and phenotypic variances for milk production.J. Dairy Sci. 1985; 68: 2278
- Mathematical contributions to the theory of evolution.—XI. On the influence of natural selection on the variability and correlation of organs.Phil. Trans. Royal. Soc. Lond. A. 1903; 200: 1
- Minimum variance quadratic unbiased estimation of variance components.J. Multivar. Anal. 1971; 1: 445
- Studies in quantitative inheritance. III. Heritability and genetic correlation in progeny tests using different mating systems.J. Genet. 1953; 51: 520
- The effect of selection on the estimation of genetic parameters.Z. Tierz. Zfich-tungsbiol. 1977; 94: 131
- Effects of selection on variances and covariances of simulated first and second lactations.J. Dairy Sci. 1979; 62: 996
- Estimation of variance components under a selection model.J. Dairy Sci. 1987; 70: 661
- Estimation of genetic variances from unselected and selected populations.J. Anim. Sci. 1984; 59: 1213
- Heritability of milk yield at different environmental levels.Anim. Prod. 1964; 6: 285
Article info
Publication history
Accepted:
October 19,
1988
Received:
August 8,
1988
Identification
Copyright
© 1989 American Dairy Science Association. Published by Elsevier Inc.
User license
Elsevier user license | How you can reuse
Elsevier's open access license policy

Elsevier user license
Permitted
For non-commercial purposes:
- Read, print & download
- Text & data mine
- Translate the article
Not Permitted
- Reuse portions or extracts from the article in other works
- Redistribute or republish the final article
- Sell or re-use for commercial purposes
Elsevier's open access license policy