A primary screen of the bovine genome for quantitative trait loci affecting carcass and growth traits

A primary genomic screen for quantitative trait loci (QTL) affecting carcas s and growth traits was performed by genotyping 238 microsatellite markers on 185 out of 300 total progeny from a Bos indicus x Bos taurus sire mated to Bos taurus cows. The following traits were analyzed for QTL effects: bir th weight (BWT), weaning weight (WW), yearling weight (YW), hot carcass wei ght (HCW), dressing percentage (DP), fat thickness (FT), marbling score (MA R), longissimus muscle area (LMA), rib bone (RibB), rib fat (RibF), and rib muscle (RibM), and the predicted whole carcass traits, retail product yiel d (RPYD), fat trim yield (FATYD), bone yield (BOYD), retail product weight (RPWT), fat weight (FATWT), and bone weight (BOWT). Data were analyzed by g enerating an F-statistic profile computed at 1-cM: intervals for each chrom osome by the regression of phenotype on the conditional probability of rece iving the Brahman allele from the sire. There was compelling evidence for a QTL allele of Brahman origin affecting an increase in RibB and a decrease in DP on chromosome 5 (BTA5). Putative QTL at or just below the threshold f or genome-wide significance were as follows: an increase in RPYD and compon ent traits on BTA2 and BTA13, an increase in LMA on BTA14, and an increase in BWT on BTA1. Results provided represent a portion of our efforts to iden tify and characterize QTL affecting carcass and growth traits.