[Direct selection for fertility and health in cattle].

Financial losses in dairy cattle due to breeding inefficiency and health impairment are so high that they should be taken into account in cattle breeding. These disturbances tend to increase as productivity increases. Although these disturbances are quantitative characteristics, they can only be recorded qualitatively. Therefore the heritabilities of breeding inefficiency and health impairment are low. Several of these disturbances (mastitis, metabolic disorders) show a much higher incidence in cows than they do in heifers. Selection for production-traits is mainly based on heifer groups of bulls. Artificial selection designed to prevent disturbances will fail to produce positive results as the heritabilities are low for heifers and the current groups of heifers are too small to obtain a reliable estimate of the breeding value of a bull for disturbances of fertility or health. Natural selection against these disturbances should not be ruled out, and therefore it is advisable to record certain disturbances and to use this recording in the selection of bull dams.