title: Estimation of dominance variance for live body weight in a crossbred population of pigs.
abstract: The objective of this study was to estimate the dominance variance for repeated live BW records in a crossbred population of pigs. Data were provided by the Walloon Pig Breeding Association and included 22,197 BW records of 2,999 crossbred Piétrain × Landrace K+ pigs from 50 to 210 d of age. The BW records were standardized and adjusted to 210 d of age for analysis. Three single-trait random regression animal models were used: Model 1 without parental subclass effect, Model 2 with parental subclasses considered unrelated, and Model 3 with the complete parental dominance relationship matrix. Each model included sex, contemporary group, and heterosis as fixed effects as well as additive genetic, permanent environment, and residual as random effects. Variance components and their SE were estimated using a Gibbs sampling algorithm. Heritability tended to increase with age: from 0.50 to 0.64 for Model 1, from 0.19 to 0.42 for Model 2, and from 0.31 to 0.53 for Model 3. Permanent environmental variance tended to decrease with age and accounted for 29 to 44% of total variance for Model 1, 29 to 37% of total variance for Model 2, and 34 to 51% of total variance for Model 3. Residual variance explained <10% of total variance for the 3 models. Dominance variance was computed as 4 times the estimated parental subclass variance. Dominance variance accounted for 22 to 40% of total variance for Model 2 and 5 to 11% of total variance for Model 3, with a decrease with age for both models. Results showed that dominance effects exist for growth traits in pigs and may be reasonably large. The use of the complete dominance relationship matrix may improve the estimation of additive genetic variances and breeding values. Moreover, a dominance effect could be especially useful in selection programs for individual matings through the use of specific combining ability to maximize growth potential of crossbred progeny.
authors.affiliation: Animal Science Unit, Gembloux Agro-Bio Tech, University of Liège, B-5030 Gembloux, Belgium Fonds pour la formation à la Recherche dans l'Industrie et dans l'Agriculture (FRIA), B-1000 Brussels, Belgium marie.dufrasne@ulg.ac.be.
authors.forename: M
authors.initials: M
authors.lastname: Dufrasne
authors.affiliation: Animal Science Unit, Gembloux Agro-Bio Tech, University of Liège, B-5030 Gembloux, Belgium.
authors.forename: P
authors.initials: P
authors.lastname: Faux
authors.affiliation: Walloon Pig Breeding Association (AWEP), B-5590 Ciney, Belgium.
authors.forename: M
authors.initials: M
authors.lastname: Piedboeuf
authors.affiliation: Walloon Agricultural Research Centre (CRA-W), B-5030 Gembloux, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Wavreille
authors.affiliation: Animal Science Unit, Gembloux Agro-Bio Tech, University of Liège, B-5030 Gembloux, Belgium.
authors.forename: N
authors.initials: N
authors.lastname: Gengler
mesh_terms: D000818:Animals; D001835:Body Weight / Q000235:genetics* / Q000502:physiology; D004777:Environment; D005260:Female; D005799:Genes, Dominant / Q000235:genetics* / Q000502:physiology; D014644:Genetic Variation / Q000235:genetics* / Q000502:physiology; D006824:Hybridization, Genetic / Q000235:genetics* / Q000502:physiology; D008297:Male; D008954:Models, Biological; D008957:Models, Genetic; D010641:Phenotype; D012044:Regression Analysis; D013552:Swine / Q000235:genetics* / Q000254:growth & development / Q000502:physiology
keywords: body weight; dominance; genetic parameter; growth; pig; random regression