Summary
A genomic screening to detect quantitative trait loci (QTL) affecting growth, carcass composition and meat quality traits was pursued. Two hundred nineteen microsatellite markers were genotyped on 176 of 620 (28%) progeny from a BrahmanโรโAngus sire mated to mostly MARC III dams. Selective genotyping, based on retail product yield (%) and fat yield (%), was used to select individuals to be genotyped. Traits included in the study were birth weight (kg), hot carcass weight (kg), retail product yield, fat yield, marbling score (400โ=โslight^00^ and 500โ=โsmall^00^), USDA yield grade, and estimated kidney, heart and pelvic fat (%). The QTL were classified as significant when the expected number of false positives (ENFP) was less than 0.05 (Fโstatistic greater than 17.3), and suggestive when the ENFP was <1 (Fโstatistic between 10.2 and 17.3). A significant QTL (Fโ=โ19; ENFPโ=โ0.02) was detected for marbling score at centimorgan (cM) 54 on chromosome 2. Suggestive QTL were detected for fat yield at 50โcM, for retail product yield at 53โcM, and for USDA yield grade at 63โcM on chromosome 1, for marbling score at 56โcM, for retail product yield at 70โcM, and for estimated kidney, heart and pelvic fat at 79โcM on chromosome 3, for marbling score at 44โcM, for hot carcass weight at 49โcM, and for estimated kidney, heart and pelvic fat at 62โcM on chromosome 16, and for fat yield at 35โcM on chromosome 17. Two suggestive QTL for birth weight were identified, one at 12โcM on chromosome 20 and the other at 56โcM on chromosome 21. An additional suggestive QTL was detected for retail product yield, for fat yield, and for USDA yield grade at 26โcM on chromosome 26. Results presented here represent the initial search for quantitative trait loci in this family. Validation of detected QTL in other populations will be necessary.