A molecular genome scan to map quantitative trait loci affecting bovine carcass weight

Abstract

Genome scan to map quantitative trait loci (QTL) is one of the efficient strategies for molecular dissection of complex traits. QTL mapping is the first step toward the detection of genes responsible for quantitative traits variation. The objective of the present research was to identify QTL influencing carcass weight in cattle. Six Limousin × Jersey crossbred sires were mated to both Jersey and Limousin dams producing 782 backcross progeny. Six sires and all the progeny were genotyped for 189 microsattelite markers. Carcass weight (CWT) was pre-adjusted to account for known fixed effects including, slaughter group, sex, year, herd, dam breed, birth type and age of dam. Residuals were stored after standardization by dividing by the phenotypic standard deviation (σP). Linkage with standardized CWT was tested, using interval-mapping regression procedure. Three genome-wide significant QTL located on BTA3, 5 and 14 and two chromosome-wide significant QTL resided on BTA10 and 17 were identified for CWT. QTL located on BTA14 was segregating in all the six families. The QTL effects raged from 0.4 to 0.8 in units of phenotypic standard deviation, thus the experiment had only a power to detect medium to large QTL.

Keywords

• carcass weight
• cattle
• genome
• qtl