Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 17, 1999
Publication Date: March 2, 2000
Citation: Casas, E., Shackelford, S.D., Keele, J.W., Stone, R.T., Kappes, S.M., Koohmaraie, M. 2000. Quantitative trait loci affecting growth and carcass composition of cattle segregating alternate forms of myostatin. Journal of Animal Science. 78:560-569. Interpretive Summary: A gene called double-muscling has previously been shown to increase meat yield and decrease fat in cattle. However, other genes may also be influencing these traits. The objective of the present study was to identify the location of other genes affecting growth and carcass traits in cattle with or without double-muscling. Locations of genes affecting these traits were detected on six different chromosomes. Three of these locations influenced more than one trait. Genes at some of these locations affected traits differently in animals with double-muscling compared to normal animals. Further studies are necessary to assess if other locations harbor genes associated with growth and carcass traits in these families. However, locations of genes reported here are suitable to be investigated in other populations.
Technical Abstract: The objective of this study was to identify additional quantitative trait loci (QTL) for economically important traits in two families segregating the mh allele. Two half-sib families were developed from Belgian Blue x MARC III (BB, n=246) and Piedmontese x Angus (PI, n=209) sires. Traits analyzed were birth (BW, kg) and yearling weight (YW, kg); hot carcass weight (HW, kg); fat depth (FD, cm); marbling score (MA); rib eye area (REA, cm2); estimated kidney, pelvic, and heart fat (KPH, %); USDA yield grade (YG); retail product yield (RP, %); fat yield (FY, %); and wholesale rib-fat yield (%). Meat tenderness was measured as Warner-Bratzler shear force at 3 (WB3, kg) and 14 (WB14, kg) d postmortem. The mh locus effect was removed by using information from six markers flanking the locus. Selective genotyping was done on 92 animals from both families to identify genomic regions potentially associated with RP and FD, using a total of 150 0informative markers in each family. Regions in which selective genotyping indicated the presence of QTL were evaluated further by genotyping the entire population and additional markers. For the BB family, a significant QTL for BW and YW was identified on chromosome 6. Suggestive QTL were identified for REA and HW on chromosome 6, and for MA on chromosomes 17 and 27. For the PI family, suggestive QTL on chromosome 5 were identified for FD, RP, and YG; and for WB3 and WB14 on chromosome 29. Interactions suggesting the presence of QTL were observed between the mh locus and chromosome 5 for WB14; and the mh locus and chromosome 14 for FD. In families segregating the mh allele, other loci influencing quantitative traits can be detected. These results are the initial effort to identify QTL affecting carcass and growth traits in these families.