A multi-parity animal model for genetic evaluation of calving traits enhanced with genomic information

Abstract

A multi-parity animal model with correlated direct and maternal effects was developed for genetic evaluation of calving ease and stillbirth, replacing the previous single-trait model used in Germany. First three parities were treated as genetically distinct traits in this new calving model, direct and maternal genetic effects of both calving ease and stillbirth were estimated jointly. Genetic parameters of the new calving model were estimated using a large data set. Low heritability values were obtained for the calving traits, genetic correlations between parities ranged from 0.47 to 0.91 indicating genetic heterogeneity between parities. A genetic evaluation software system was developed for German Holstein, Red Dairy Cattle and Jersey breeds based on this multi-parity calving model. Genetic trends of the new model were validated using Interbull trend validation method III. Reasonably high genetic correlations were obtained between Germany and major dairy countries in a MACE test evaluation. SNP effects were estimated for German Holstein using EuroGenomics genotypes and the most recent MACE evaluation. In order to determine the optimal residual polygenic variance for each trait, five scenarios of residual polygenic variance, 0%, 1%, 5%, 10% and 20%, were investigated. With the optimal residual polygenic variances, the genomic evaluation model was validated. In April 2012, the multi-parity calving model was officially introduced in Germany for conventional genetic and genomic evaluations of the calving traits.