Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/12/2003
Publication Date: 4/1/2004
Citation: Li, C., Basarab, J., Snelling, W.M., Benkel, B., Kneeland, J., Murdoch, B., Hansen, C., Moore, S.S. 2004. Identification and fine mapping of quantitative trait loci for backfat on bovine chromosomes 2, 5, 6, 19, 21, and 23 in a commercial line of Bos taurus. Journal of Animal Science 82:967-972. Interpretive Summary: Backfat thickness is a major trait that affects carcass value in beef cattle. In this study, we identified regions influencing estimated breeding values for backfat thickness on chromosomes 2, 5, 6, 19, 21, and 23 in a commercial line of cattle. Twelve sets of adjacent DNA markers, covering nine different chromosomal regions were associated with estimated breeding values for backfat. Chromosomes 6 and 19 each contained three segments influencing backfat, and chromosomes 5, 21, and 23 all contained a single region with markers associated with backfat. None of the sets of markers on chromosome 2 were associated with backfat. The results provide a useful reference for further research to examine specific genes that may influence backfat, and develop DNA tests to assist selection for backfat.
Technical Abstract: Backfat thickness is one of the major quantitative traits that affects carcass quality in beef cattle. In this study, we identified and fine-mapped QTL for backfat EBV on bovine chromosomes 2, 5, 6, 19, 21, and 23 using an identical-by-descent haplotype-sharing analysis in a commercial line of Bos taurus. Eleven haplotypes were found to have significant associations with backfat EBV at the comparison-wise P-value threshold, and one at the chromosome-wise P-value threshold on bovine chromosomes 5, 6, 19, 21, and 23. On average, the 12 significant haplotypes had an effect of 0.62 SD on backfat EBV, ranging from 0.38 SD to 1.33 SD. The 12 significant haplotypes spanned nine chromosomal regions, one on chromosome 5 (65.4 to 70.0 cM), three on 6 (8.2 to 11.8 cM, 63.6 to 68.1 cM, and 81.5 to 83.0 cM), three on 19 (4.8 to 15.9 cM, 39.4 to 46.5 cM, and 65.7 to 99.5 cM), one on 21 (46.1 to 53.1 cM), and one on 23 (45.1 to 50.9 cM). Among the nine chromosomal regions, six were new QTL regions and three showed remarkable agreement with QTL regions that were previously reported. Eight of the nine QTL regions were localized to less than or close to 10 cM in genetic distance. The results provide a useful reference for further positional candidate gene research and marker-assisted selection for backfat.