Submitted to: World Congress of Genetics Applied in Livestock Production
Publication Type: Proceedings
Publication Acceptance Date: May 17, 2002
Publication Date: August 16, 2002
Citation: Ashwell, M.S., Schnabel, R.D., Sonstegard, T.S., Van Tassell, C.P. 2002. Fine-mapping of qtl affecting protein percent and fat percent on bta6 in a popular u.s. holstein family. World Congress of Genetics Applied in Livestock Production. 31:123-126.
Interpretive Summary: From previous studies, we found a chromosomal region that contains genes affecting the protein and fat percentages in milk. We studied additional DNA markers on chromosome 6 in a popular U.S. Holstein family in an attempt to pinpoint the location of the gene(s). Ninety-one sons of the popular sire were studied at 28 DNA markers. The data was analyzed using two different statistical methods. Both methods placed an important gene(s) between DNA markers BMS5037 and BMS518. Incorporation of this DNA information may give rise to a greater rate of genetic improvement for dairy producers.
Results from numerous genome-scans have identified putative QTL affecting milk production, health and conformation in different dairy populations. In our genome scan, we detected a highly significant QTL on BTA6 affecting milk protein percent and evidence of a QTL affecting fat percent on the same chromosome in one U.S. Holstein family using the granddaughter design. .Due to the large number of statistical tests involved in the genome-scan and the simplistic nature of the analysis, the significant marker-trait associations were studied further to refine the QTL map position. Twenty eight markers were genotyped in 91 sons of a popular Holstein sire. Data was analyzed using a least squares regression method (QTL Express) and a variance components method (SOLAR). Both methods placed a QTL affecting protein percent between 55 and 65cM on the linkage map, between markers BMS5037 and BMS518.