GENETIC-RELATIONSHIPS BETWEEN CLINICAL MASTITIS, SOMATIC-CELL COUNT, AND UDDER CONFORMATION IN DANISH HOLSTEINS

Heritabilities and genetic and phenotypic correlations were estimated for linear scored udder traits, clinical mastitis, incidence of other diseases, and somatic cell count (SCC), using first lactation data from the Danish young sire sampling program. Two sets of data were analyzed using a multi-trait REML procedure with an animal model. Heritabilities were low for mastitis (0.025) and other diseases (0.011). Heritability of SCC was 0.18. For type traits, heritability estimates varied between 0.07 and 0.43. The estimate of the genetic correlation between SCC and clinical mastitis was high at 0.97. Genetic correlations between health and type traits were generally low ( - 0.32 to 0.37) with few exceptions. The genetic correlation between clinical mastitis and other diseases was moderately high at 0.53. All phenotypic correlations between traits were low. In general, the results indicate that selection for improved udder conformation will reduce the increase in SCC and clinical mastitis associated with selection for production. The high genetic correlation between SCC and clinical mastitis makes SCC a feasible indicator for clinical mastitis.