Evaluation of genomic breeding values for exterior of Holstein cattle in CR

ZAVADILOVÁ, Ludmila, PŘIBYL, Josef, VOSTRÝ, Luboš and PEŠEK, Petr. Evaluation of genomic breeding values for exterior of Holstein cattle in CR. Výzkum v chovu skotu/Cattle Research, 2017, vol. 59(2), p. 2-11. ISSN 0139-7265.
CathegoryPublication in specialized journals
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The paper deals with the prediction of genomic breeding values for exterior of Holstein cattle, which took place in 2015. Breeding values, conventional and genomic, were estimated in February 2015 using data from 405,855 heifers and in September 2015, when data were available from 443,237 heifers. A linear animal model with fixed effects herd and date of classification and classifier, linear and quadratic regressions on age at first calving and days in milk and the random effects of the animal and residuum was employed. The genomic breeding values were predicted by the single-step method of genomic evaluation. Correlations of genomic and conventional breeding values within each season exceeded 99 %. When comparing conventional and genomic values for 26,727 bulls, the correlations between the breeding values were mostly above 98 % except the width of the chest, locomotion and dairy strength, with correlations higher than 88 %. If we compared correlations between the conventional and genomic values for 2,453 genotyped bulls, then most correlations inside the prediction seasons were higher than 90 %. Regarding genetic trends, no important differences between the genomic and conventional values were found. Genetic progress was achieved in all of the traits in both, bulls and cows. The positive progress in udder traits was observed, mainly in the udder as complex trait, which is expressed in percentages. Regarding the comparison between conventional and genomic breeding values, the largest difference in favor of the genomic values was displayed in the dairy strength. Positive trend was observed for locomotion. For other feet and legs traits, the genetic progress was not pronounced. The ranking of animal by conventional and genomic breeding values is similar. For young bulls are genomic breeding values higher than conventional.