Submitted to: Animal Genetics International Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/2006
Publication Date: 8/20/2006
Citation: Feijo, G.L., Kirkpatrick, B.W., Casas, E. 2006. Linkage disequilibrium mapping of meat quality QTL [abstract]. Proceedings of the 30th International Conference on Animal Genetics (ISAG), August 20-26, 2006, Porto Seguro, Brazil. p. 100. Paper No. D526. Interpretive Summary:
Technical Abstract: Previous studies based on linkage analysis have identified broad areas in the bovine genome associated with meat quality. Linkage disequilibrium (LD) analyses have the potential to identify narrower regions and point towards candidate genes. Tenderness and marbling were chosen to be evaluated in a fine-mapping project exploiting LD of maternally inherited alleles. Two paternal half-sib families, where linkage effects were known and accounted for, were chosen to evaluate LD. Each family was composed of more than 500 offspring produced by mating two Bos taurus x Bos indicus crossbred sires with Bos taurus crossbred dams from the Germplasm Evaluation Project Cycle IV (MARC, USDA, Clay Center, NE). Phenotypes for meat tenderness, measured as Warner Bratzler shear force at 14 days postmortem (kg), and marbling were adjusted within family for fixed effects (sex, days on feed, dam line and year) and the probability of inheriting alternative QTL alleles from the sire at the given chromosomal region. Offspring of each sire were ranked using residuals from the models and equal amounts of DNA from 7% of the animals with the highest, and 7% with the lowest values for each trait. DNA was hybridized to a microarray containing approximately 10,000 SNPs (Affymetrix®), and the normalized allele intensities were used to define allele frequencies in the pools. Allele frequency difference between high and low pools was calculated and used to generate point-wise significance. Chromosome maps, containing point-wise values and running averages of five consecutives SNPs, were plotted. Regions with significant markers nominal P<.01), with significant running averages previously were considered as candidate regions. Regions on BTA 2, 5, 9, 14 and 29 showed preliminary association with marbling, and a region on BTA 5 was associated with tenderness. Significant markers in those areas have been chosen for individual genotyping to validate pool typing results.