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Journal of Dairy Science Vol. 84 No. 4 987-
© 2001 by American Dairy Science Association ®
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ONLINE ONLY Additive and Dominance Genetic Variance of Fertility by Method real and Preconditioned Conjugate Gradient

T. Druet 1, J. Sölkner 2, A. F. Groen , and N. Gengler 3

1 National Fund for Scientific Research, B-1000 Brussels, Belgium and Animal Science Unit, Gembloux Agricultural University, B-5030 Gembloux, Belgium
2 Department of Livestock Science, University of Agriculture, A-1180 Vienna, Austria
3 Animal Breeding and Genetics Group, Wageningen Institute of Animal Science, Wageningen University, NL-6700 AH Wageningen, The Netherlands

The objectives of this study were threefold: 1) estimation of additive and dominance genetic variances for fertility traits for Austrian Simmental and Brown Swiss dairy cattle; 2) use of method real and the preconditioned conjugate gradient compared to solving for method real by second-order Jacobi iteration; and 3) study of the impact of inclusion of parental subclass effects on solutions for other random effects. Dominance variances were modeled for the inseminated cow and ranged from 0.32 to 1.36% of total variance. These values were similar to values for additive effects, which were approximately 1% of total variance. Convergence was clearly improved with preconditioned conjugate gradient and number of extrapolations reduced. Variance for permanent environment under a model without dominance could be split into a new estimate of permanent environmental variance and parental subclass variance. Solutions for parental subclass dominance effects were approximately proportional to permanent environment effects, but highly dependent on the number of animals contributing dominance relationships, especially full-sibs and three-quarter-sibs. For animals with a lot of dominance information (full-sibs, three-quarter-sibs, cousins), permanent environment and parental subclass dominance effects were nearly independent. Changes in additive effects were negligible, probably because both variances for parental subclass dominance effects and additive genetic effects were very small compared with residual variance.

Key Words: variance component estimation • dominance • fertility

Submitted on January 11, 2000
Accepted on December 22, 2000




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J. Bormann, G. R. Wiggans, T. Druet, and N. Gengler
Within-Herd Effects of Age at Test Day and Lactation Stage on Test-Day Yields
J Dairy Sci, November 1, 2003; 86(11): 3765 - 3774.
[Abstract] [Full Text] [PDF]


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