Submitted to: American College of Veterinary Internal Medicine
Publication Type: Proceedings
Publication Acceptance Date: March 5, 2002
Publication Date: March 5, 2002
Citation: ASHWELL, M.S., SONSTEGARD, T.S., VAN TASSELL, C.P. MAPPING GENES RELATED TO DISEASE RESISTANCE AND MILK PRODUCTION IN U.S. HOLSTEINS. AMERICAN COLLEGE OF VETERINARY INTERNAL MEDICINE. vol. 20, pp. 264-66, 2002. Technical Abstract: Results from a genome scan conducted in 8 US Holstein families to identify quantitative trait loci (QTL) affecting economically important traits, such as conformation, health, fertility and milk production, are presented. A total of 155 microsatellite markers located throughout the bovine genome were selected for the scan. Effects of marker alleles were analyzed for 38 traits including traits for milk production, somatic cell score, productive life, conformation and calving ease. Ten chromosomes had significant marker-trait associations identified from within- and across- family analyses. Two chromosomes (6 and 14) had significant effects on milk composition traits and chromosome 7 had a significant effect on somatic cell score. Significant effects on conformation traits, especially rump angle, were found on 8 other bovine chromosomes. The QTL identified in this genome scan may be useful for marker-assisted selection to increase the rate of genetic improvement on traits such as disease resistance and conformation traits associated with fitness while maintaining or accelerating genetic improvement for production. Before incorporation in marker-assisted selection programs, these potential QTL must be validated in other populations or newer generations of the original families. Validation studies are underway for QTL affecting dairy form and protein percentage on chromosomes 27 and 6, respectively. The strategy being used to confirm the QTL and fine-map their locations for application in industry selection decisions is also discussed.