Estimation of Genetic and Phenotypic Parameters for Selection Index Evaluation in the Danish Pig Breeding Program

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Abstract
Genetic and phenotypic parameters were estimated for Danish Landrace in two health environments, conventional and SPF and for Yorkshire in the SPF environment. Seven traits were considered, four of which entered in the breeding objective, while the remaining three were correlated traits. The composition of the three data sets were respectively, 1612 progeny test groups of 747 sires, 476 progeny test groups of 187 sires and 398 progeny test groups of 147 sires. The genetic parameters were estimated from a paternal half-sib analysis. Indications of assortative mating were found, but the influence from this on the estimated additive genetic variances were in most cases reduced by covariates describing the genetic potential of the dams. The bending procedure (Hayes & Hill, 1981) was applied to obtain estimates within the parameter space. The extent of bending and modifications of the bending procedure is commented on. Recommendations on the use of the estimated parameters are given.