Genetic parameters for clinical mastitis, somatic cell score, production, udder type traits, and milking ease in first lactation Holsteins

Genetic parameters were estimated by restricted maximum likelihood with an animal model on first lactation data of 29,284 French Holstein cows for cli nical mastitis, lactation somatic cell score, milking ease, production, and nine udder type traits. The heritability was low for clinical mastitis (0. 024), moderate for lactation somatic cell score (0.17) and milking ease (0. 17), and ranged from 0.17 to 0.30 for type traits. A high (0.72) but lower than unity genetic correlation was found between clinical mastitis and lact ation somatic cell score and indicated that both traits were genetically fa vorably associated. The antagonism with production was stronger for clinica l mastitis than for lactation somatic cell score (genetic correlations 0.45 and 0.15, respectively). Udder depth, fore-udder attachment, and udder bal ance were favorably associated with lactation somatic cell score and clinic al mastitis with genetic correlations ranging from -0.29 to -0.46, whereas low correlations were found with teat length. Milking ease was found to be unfavorably correlated with lactation somatic cell score (genetic correlati on 0.44) but not with clinical mastitis.