GENETIC CORRELATIONS AMONG SOMATIC-CELL SCORES, PRODUCTIVE LIFE, AND TYPE TRAITS FROM THE UNITED-STATES AND UDDER HEALTH MEASURES FROM DENMARK AND SWEDEN

Sire genetic evaluations for protein yield, somatic cell score (SCS), productive life, and udder type traits from the US were correlated wit h sire evaluations for udder health from Denmark and Sweden and then t he correlations were adjusted for accuracies to approximate genetic co rrelations. Traits from Denmark and Sweden included somatic cell count (SCC) and clinical mastitis from single-trait analyses. In addition, evaluations for clinical mastitis from Denmark and Sweden were regress ed on US traits to test for quadratic relationships. Information from 85 bulls with US and Danish evaluations (77 with US type) and from 80 bulls with US and Swedish evaluations (79 with US type) was used to ca lculate correlations. Genetic correlations of US protein yield with Da nish and Swedish SCC and clinical mastitis were all unfavorable (-0.09 to -0.32). Genetic correlations of US productive life with Danish and Swedish SCC and clinical mastitis were all favorable (0.06 to 0.59). Genetic correlations between US SCS and Danish SCC and between US SCS and Swedish SCC were -0.87 and -0.99, respectively (favorable). Geneti c correlations between US SCS and Danish clinical mastitis and between US SCS and Swedish clinical mastitis were -0.66 and -0.49, respective ly (favorable). The US type traits that had the largest correlations w ith clinical mastitis from Denmark and Sweden, respectively, were udde r composite (0.26, 0.47), udder depth (0.45, 0.52), and fore udder att achment (0.31, 0.34). In general, quadratic regressions indicated litt le nonlinearity between clinical mastitis and the US traits. Specifica lly, the US bulls with the lowest predicted transmitting abilities for SCS had the most favorable rates of daughter clinical mastitis in Den mark and Sweden. Selection for increased productive life, lower SCS, a nd more shallow udders should improve mastitis resistance.