Genomic and conventional breeding values for clinical mastitis

Abstract

Conventional and genomic breeding values for clinical mastitis were estimated,based on a dataset of 15,905 cows (36,250 lactations) from 10 farms, calving years from 1996 to 2014. The number of genotyped bulls was 2647 and 799 of them had offspring among the surveyed cows. Pedigree consisted of 64,306 individuals. Analyzed trait was defined as the number of incidence of clinical mastitis per standard lactation. Parity was limited from 1 to 7. The highest proportion of mastitis disease was observed in early lactation and decreased with month of lactation, while there was an upswing of diseases with parity. Genetic trend for cows showed a deteriorating tendency for clinical mastitis. From 1992 to 2010 there was a rise in the relative values of breeding values from 88% to 112% (worsening). Relative breeding values of these bulls were on average above 100%. The correlations between classical genomic breeding values and the values were high: 93% for the whole sample, 81% to 48 young genomic bulls without daughters born in years 2011 and 2012.