Genet. Sel. Evol. 39 (2007) 181-193
DOI: 10.1051/gse:2006041

Non-additive genetic effects for fertility traits in Canadian Holstein cattle (Open Access publication)

Valentina Palucci^a, Lawrence R. Schaeffer^a, Filippo Miglior^{b, c} and Vern Osborne<sup>d

a</sup>  Centre for Genetic Improvement of Livestock, University of Guelph, Guelph Ontario, N1G 2W1 Canada
^b  Agriculture and Agri-Food Canada, Dairy and Swine Research and Development Centre, Lennoxville, QC, Canada, J1M 1Z3
^c  Canadian Dairy Network, Guelph, ON, Canada, N1G 4T2
^d  Department of Animal and Poultry Science, University of Guelph, Guelph Ontario, N1G 2W1 Canada

(Received 9 March 2006; accepted 6 November 2006 ; published online 17 February 2007)

Abstract - The effects of additive, dominance, additive by dominance, additive by additive and dominance by dominance genetic effects on age at first service, non-return rates and interval from calving to first service were estimated. Practical considerations of computing additive and dominance relationships using the genomic relationship matrix are discussed. The final strategy utilized several groups of 1000 animals (heifers or cows) in which all animals had a non-zero dominance relationship with at least one other animal in the group. Direct inversion of relationship matrices was possible within the 1000 animal subsets. Estimates of variances were obtained using Bayesian methodology via Gibbs sampling. Estimated non-additive genetic variances were generally as large as or larger than the additive genetic variance in most cases, except for non-return rates and interval from calving to first service for cows. Non-additive genetic effects appear to be of sizeable magnitude for fertility traits and should be included in models intended for estimating additive genetic merit. However, computing additive and dominance relationships for all possible pairs of individuals is very time consuming in populations of more than 200 000 animals.

Key words: fertility / gene interactions / dairy cattle / non-additive models

Correspondence and reprints: vpalucci@uoguelph.ca

© INRA, EDP Sciences 2007