Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 19, 1998
Publication Date: N/A
Interpretive Summary: Genetic linkage maps in livestock provide the basis for mapping traits of economic interest that are influenced by multiple genes. The chromosomal regions affecting these types of traits are referred to as quantitative trait loci (QTL). Data gathered on QTL affecting traits that are impractical and/or expensive to measure during early phase of the life cycle have the greatest potential to impact genetic selection through marker-assisted selection. Exemplary of such traits are those influencing meat quality and yield. We have utilized progeny from a Brahman x Hereford sire to identify several chromosomal regions that influence carcass traits. In particular, we have identified a region on chromosome 5 where inheritance of the Brahman form of the genetic material (allele) results in an increase in carcass bone compared to the Hereford allele. Suggestive statistical evidence has been obtained for several traits being influenced by multiple QTL on multiple chromosomes. This is one of our initial reports on carcass QTL. Our target is to identify QTL with sufficient effects on carcass and meat traits to use markers to predict the genetic merit of individual animals.
A primary genomic screen for quantitative trait loci (QTL) affecting carcass and growth traits was performed by genotyping 238 microsatellite markers on 187 out of 300 total progeny from a Bos indicus x Bos taurus sire mated to Bos taurus cows. Traits analyzed for QTL effects were: birth weight (BW), weaning weight (WW), yearling weight (YW), hot carcass weight (HCW), dressing percentage (DP), fat thickness (FT), marbling score (MAR), rib eye area (REA), rib bone (RibB), rib fat (RibF), and rib muscle (RibM), and the predicted whole carcass traits, retail product yield (RPYD), fat trim yield (FATYD), bone yield (BOYD), retail product weight (RPWT), fat weight (FATWT), and bone weight (BOWT). Data were analyzed by generating an F-statistic profile computed at 1 cM intervals for each chromosome by the regression of phenotype on the conditional probability of receiving 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 D on chromosome 5 (BTA5). Putative QTL at or just below the threshold for genome wide significance were: an increase in RPYD and component traits on BTA2 and BTA13, an increase in REA on BTA14, and an increase in BW on BTA1. Results provided represent a portion of our efforts to identify and characterize QTL affecting carcass and growth traits.