QTL analysis of beef fat colour and the effect of BCD02

Abstract

Most agricultural economic traits are controlled by both the environment and genetics. Locating quantitative trait loci (QTL) using molecular markers remains a key approach to identify the genes controlling those traits. In this study, the QTL for fat colour in beef cattle were mapped. The mapping herd was a double-backcross design using two extreme Bos taurus breeds (the Jersey dairy breed and Limousin beef breed). Three fat colour traits were measured (beta-carotene concentration in subcutaneous fat and fat colour scores of biopsy and carcass fat), and a total of 16 QTL on 13 chromosomes were detected at the 5% genome-wise significance level. A potential candidate gene in QTL on BTA 15, β, β-carotene-9’, 10’-dioxygenase (BCDO2) was investigated. A SNP in exon 3 which creates a stop codon was previously identified, and inclusion of this BCDO2 SNP as a fixed effect in the linkage analysis of the fat colour traits changed the F-values for a number of QTL. As expected, the QTL on BTA 15 was no longer significant. As the presence of the BCDO2 genotype in the model reduced the residual variance, three additional QTL were detected for biopsy fat colour score and one additional QTL for carcass fat colour score.