Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/23/2003
Publication Date: 8/1/2003
Citation: Moore, S.S., Li, C., Basarab, J., Snelling, W.M., Kneeland, J., Murdoch, B., Hansen, C., Benkel, B. 2003. Fine mapping of quantitative trait loci and assessment of positional candidate genes for backfat on bovine chromosome 14 in a commercial line of Bos taurus. Journal of Animal Science 81:1919-1925. Interpretive Summary: Backfat thickness is a quantitative trait with substantial effect on beef carcass value. In this study, we used combinations of DNA markers to determine regions of cattle chromosome 14 that influence backfat, and examined relationships between markers for two specific genes and estimated breeding values for backfat in commercial seedstock lines. The region of chromosome 14 we found to be associated with backfat agrees with other studies. Our data did not indicate any association between single-nucleotide polymorphism markers for either gene, diacylgcerol acyltransferase 1 (DGAT1) and thyroglobulin (TG), and backfat estimated breeding values. We did, however, detect a strong association between an anonymous marker, located about half-way between the two genes, and backfat. These results suggest that other polymorphisms in the two genes, as well as other genes located in the chromosomal region should be examined for effects on backfat.
Technical Abstract: Backfat thickness is one of the major quantitative traits that affect carcass quality in beef cattle. In this study, we have fine mapped a QTL for backfat EBV on bovine chromosome 14, using an identical-by-descent haplotype-sharing analysis, in a commercial line of Bos taurus. We also examined the association between gene-specific single nucleotide polymorphism (SNP) markers of the genes diacylgcerol acyltransferase 1 (DGAT1) and thyroglobulin (TG) and the backfat EBV. The results indicate that the QTL region for backfat identified on chromosome 14 is in agreement with previous studies. However, neither of the two polymorphisms of candidate genes tested, DGAT1 nor TG, showed a significant (P > 0.10) association with the backfat EBV in the cattle populations examined. However, a strong association (P = 0.0058) was detected between a microsatellite marker (CSSM66) lying approximately mid-way between the two candidate genes and the backfat EBV. These results suggest that other SNP of DGAT1, TG, or other gene(s) in the chromosomal region should be examined to test whether they have a significant effect on lipid metabolism.