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item Van Tassell, Curtis - Curt
item Ashwell, Melissa
item Sonstegard, Tad

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/24/2000
Publication Date: 8/1/2000
Citation: Van Tassell, C.P., Ashwell, M.S., Sonstegard, T.S. 2000. Detection of putative loci affecting milk, health, and conformation traits in a u.s. holstein population using 105 microsatellite markers. Journal of Dairy Science. 83(8):1865-1872.

Interpretive Summary: The objective of this study was to identify DNA markers that could be used in the selection of bulls, with our long-term goal being to identify chromosomal regions important for milk production, health, and conformation traits in the US commercial Holstein population. Detection of genetic markers located near important genes controlling these traits might be rewarding to breeders and also to researchers for use in marker-assisted selection. Over 100 DNA markers located on all 28 chromosomes were studied in eight large US Holstein families. Variations with some of these DNA markers were associated with significant effects for milk production traits in several families. Selection of these markers may increase genetic gain within these families and increase profits and sustainability for the US artificial insemination industry.

Technical Abstract: Quantitative trait loci affecting milk yield, health, and conformation traits were studied for eight large US Holstein grandsire families using the granddaughter design. A total of 105 microsatellite markers located throughout the bovine genome were selected for the scan. The data analyzed include genotypes for 35 markers in 8 families not previously reported and genotypes for 70 markers reported previously in 7 of those families. Analyses of markers previously reported were updated. Effects of marker alleles were analyzed for 38 traits including traits for milk production, somatic cell score, productive life, conformation, calving ease, and 16 canonical traits derived from conformation and production traits. Permutation tests were used to calculate experiment-wise error rates. A trait-wise critical value of P=0.1 was used to determine significance. Eight putative quantitative trait loci associated with 7 of the 35 new markers were identified within specific families. Two of these markers were associated with differences in strength and rump angle on chromosomes 4 and 9, respectively. Different markers were associated with protein percentage, milk yield, and somatic cell score on chromosomes 6, 7, and 10 in different families. Additional marker- trait combinations were identified in the across family tests including effects on chromosomes 3 and 4 for protein percentage and body depth, respectively. Additional markers are being added to allow interval analysis where putative quantitative trait loci have been identified and to increase marker density.