Genetic improvement of dairy cattle health

J.B. Cole1, P.D. Miller2, and H.D. Norman1

1Animal Improvement Programs Laboratory, Agricultural Research Service, USDA, Beltsville, MD 20705-2350

2Department of Dairy Science, University of Wisconsin, Madison, WI


Genetic response has been well documented when cows are selected based upon breeding values from national genetic evaluations of field-recorded traits. This response is steady and the gains accumulate over time. There is increasing interest in breeding dairy cows that will be healthier and remain in the herd longer. Direct and indirect costs associated with disease represent a major expense to the producer, and selection for improved health may reduce these costs significantly. Considerable genetic variability exists for several health traits in dairy cattle, including mastitis, ketosis, displaced abomasum and lameness. This genetic variation is not currently being efficiently utilized for genetic improvement. Somatic cell score has been used to select for improved resistance to mastitis in the United States. Significant genetic gains in productive life are being achieved by selecting sires whose daughters produce more, conceive faster, calve easier, and live longer than their contemporaries. Four Scandinavian countries currently provide genetic evaluations for clinical mastitis and place more emphasis on health and fitness traits in their national selection programs. The statistical tools and computing resources needed for routine health genetic evaluations are available, but the necessary data are not. A standard set of health and fitness event codes is not used by participants in the Dairy Herd Improvement program and on-farm management software. The USDA Animal Improvement Programs Laboratory is currently developing a data exchange format for the routine collection of health and fitness data from dairy cattle throughout the United States that includes a set of standard event codes. Events have been included in the format based on frequency of occurrence in field data, economic impact, and consultation with veterinarians. A health event record includes detailed cow identification, a health event code, an event date, and an optional detail field. This format can provide the data necessary for research and the implementation of routine genetic evaluations for economically-important health traits. Uniform management codes that can also be used for genetic evaluations for health traits of economic significance will provide dairy producers with a valuable tool for improving the efficiency and profitability of their cows.

(Key words: genetic evaluation, dairy cattle, health)