Genetic correlations between production with disease resistance and fertility in dairy cattle and consequences for total merit selection

Twelve years of data from progeny-test results of 1486 Swedish Red and Whit e (SRB) and 756 Swedish Black and White (SLB) AI bulls were analysed to pro vide estimates of genetic correlations between yield of protein and three h ealth- and fertility traits. For both breeds, the correlations were unfavou rable (r(G) = -0.13 to -0.37). The effects of negative genetic correlations (compared to a situation with genetic correlations with zero values) on th e b-values in the total merit index of bulls were rather small but the effe cts on the estimated genetic gain were large. The effect of not including h ealth and fertility traits in the index, although included in the breeding goal, resulted in a 9-10% reduced accuracy of estimated breeding values for total merit and thus a corresponding loss in total gain.