Possibilities for genetic improvement of disease resistance, functional traits and animal welfare

It is evident that improved genetic capacity for production in many dairy c attle populations may result in genetic deteriorations of health traits, fe rtility and calving performance. In spite of low heritabilities of these tr aits, considerable genetic variation, and so possibilities for genetic impr ovements, exist. From both an economic and an animal welfare point of view the functional traits are of great importance. In the Nordic countries, com prehensive breeding efforts to improve these traits have therefore been und ertaken, and in this connexion the concept the "Nordic Profile" has been in troduced. In a closed breeding scheme the effect of including non-productio n traits in the breeding goal may be substantial, but if the sires of the m ajority of the test bulls are selected for production alone, the effect of selecting proven bulls and bull dams for non-production traits is negligibl e. By means of deterministic computer simulations the expected genetic chan ges in production, health, fertility, calving performance and other functio nal traits were estimated for alternative breeding schemes, breeding object ives and reproductive strategies. In contrast to multitrait selection, sing le-trait selection for production led to substantial deterioration of most functional traits. In monetary units the aggregate response from single-tra it selection was 26% less than the response from multitrait selection. Hybr id schemes-with nucleus herds and use of multiple ovulation or ovum pick up and progeny testing of nucleus-born young bulls-were 25-50% superior to co nventional schemes. In all schemes with multitrait selection, 20-25% of the total genetic gain was due to improvement of non-production traits. It is concluded that combined use of target goals and economic goals may lead to substantial genetic progress, and may put the breeders in a better position to cope with the consumers' and politicians' increasing concern about anim al welfare.