Detection of quantitative trait loci affecting muscle histochemical properties in the F₂ progeny of a cross between Japanese black and limousin breed

With a view towards, the genetic improvement of economically important traits, we previously generated a beef cattle F₂ resource population from a Japanese Black and Limousin cross. Here, we report on a genome-wide scan for QTLs affecting muscle fiber diameter and composition traits. The longissimus thoraces muscle samples from 150 F₂ animals were examined to determine muscle fiber type and diameter. At the same time, F₂ animals as well as the F₁ parents and F₀ grandparents were genotyped for 313 informative micro satellite markers that spanned 2.382 cM of the Bovine autosomes. The results of a genome scan using least-squares regression interval mapping provided evidence for a QTL affecting the diameter of the red muscle fiber (<5% chromosome-wide level) at 42 cM on BTA17; a QTL affecting the composition of the red and white muscle fibers (<5% chromosome-wide level) at 0 cM on BTA5 and a QTL affecting the composition of the red muscle fiber (<5% chromosome-wide level) at 106 cM on BTA8. Thus in this study, we detected 3 QTLs for 3 traits. The detected QTLs were either contiguous with or overlapped previously reported QTLs with effects on several traits assumed to be related to muscle histochemical properties.