GWAS in practical cattle breeding in Czech Republic: single step method, genetic progress

Abstract

Development of genetic evaluation of animals is permanent process. It was going from estimated breeding value (EBV) calculated by CC-test, across a BLUP – animal model and RR-TDM, to the genomic enhanced breeding value (GEBV) using genetic markers. Methods of genetic evaluation become a part of marketing strategies of insemination companies. Therefore all countries and association of breeders seek to be compatible with others. Now we are in a period of massive global implementation of genomic evaluation, which combines traditional BLUP with huge quantity of genetic SNP markers. Multi-step procedures are now usual in practice, which work with deregressed proofs. Development of methods attained to the single-step procedure (ssGBLUP) which overcomes some difficulties of previous methods, improves reliabilities of evaluation and compares all animals, genotyped and ungenotyped, in entire nation-wide population. Genomic evaluation influence above all young genotyped animals. In Czech Republic single-step procedure is routinely used for national evaluation of milk, linear type traits, reproduction and longevity. GEBVs are accompanied by genomic reliabilities. Genetic trends over last 20 years are in some traits different for genomic evaluation compared to traditional BLUP evaluation, although input data and genetic parameters (heritability) are the same and genotyped animals were only small proportion from entire evaluated population. Differences in genetic trends increase mainly in new batches of animals. Reason of it could be in the changed variability of breeding values and “genomic correction” of relationship between animals, which is expanded from genotyped animals to others individuals in a population.

Keywords

• genomic breeding value
• single-step
• genomic relationship
• genetic trend