Experiences of including reproduction and health traits in Scandinavian dairy cattle breeding programmes

Abstract

Reproduction and health traits are of significant economic importance for dairy production. Most of these traits are expressed in a categorical way and show heritabilities of 5% or less. Nevertheless, their additive genetic variation is considerable. For example, the incidence of clinical mastitis in the first lactation varies among daughter groups of Swedish Holstein bulls between 10 and 26%, stillbirth rate at first parity between 3 and 16%, and the number of inseminations per serviced cow between 1.6 and 1.9. Unfavourable genetic correlations of the order of 0.2–0.4 between production on one side, and mastitis and female fertility on the other, have generally been found. Well integrated recording schemes in the Scandinavian countries enabled early the adoption of total merit indexes (TMI), including reproduction and health traits, into their selection schemes. In practice, TMI selection has proven to be effective in maintaining functional efficiency of the cows simultaneously with a sharp increase in production. As bull selection nowadays takes place globally, sustainable breeding programmes require more extensive recording and genetic evaluations of reproduction and health traits internationally, a development that presently grows quickly. The Scandinavian experiences are reviewed in this paper in the light of this international development.