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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #120760
Title: GENOME-WIDE SCANS FOR QTL AFFECTING CARCASS TRAITS IN HEREFORD X COMPOSITE DOUBLE BACKCROSS POPULATIONS

Author
item Macneil, Michael
item GROSZ, MICHAEL - MONSATO

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/8/2002
Publication Date: 9/1/2002
Citation: MACNEIL, M.D., GROSZ, M.D. GENOME-WIDE SCANS FOR QTL AFFECTING CARCASS TRAITS IN HEREFORD X COMPOSITE DOUBLE BACKCROSS POPULATIONS. JOURNAL OF ANIMAL SCIENCE. 2002. V. 80. P. 2316-2324.

Interpretive Summary: Identifying quantitative trait loci (QTL) is an essential step in exploiting genomic information to accelerate genetic improvement of beef cattle. Reducing external fat without compromising marbling and controlling portion size are proposed breeding objectives that may lead to greater consumer satisfaction with beef. Previous investigations have relied on diverse breeds, one or the other of which would not be adapted to commercial production in northern latitudes. In this research, we used Line 1 Hereford and a composite composed of Red Angus, Charolais, and Tarentaise. Both Line 1 and the composite are well adapted to beef production in the Northern Great Plains. We identified several QTL affecting carcass characteristics indicative of the size of beef cuts and the relative amounts of lean and fat they contain. The results of this research provide a foundation for further refinement of the QTL locations and identifying closely linked genetic markers. When they are identified, these closely linked markers can be used in marker assisted selection for genetic improvement of carcass attributes without either the expense or prolonged generation intervals that result from progeny testing.

Technical Abstract: A genome-wide scan for chromosomal regions influencing carcass traits was conducted spanning 2.214 Morgans on 29 bovine autosomes using 170 microsatellite markers. There were 151 backcross progeny from a single Hereford x composite (CGC) bull. Cattle were fed out and slaughtered serially over 13 wk when they were 614 to 741 d of age. Phenotypes measured at harvest were: live weight, (LW),carcass weight (CW), slaughter weight (SW), fat depth (FD), marbling (MB), percentage kidney, pelvic, and heart fat (KPH fat), and ribeye area (RE). Dressing percent (DP) and USDA Yield Grade (YG) were calculated from these data. Phenotypes were adjusted to age-, weight-, and fat-constant endpoints. Interval mapping was used to detect QTL. Nominal significance was established by permutation analysis. A secondary genomic scan was similarly conducted, after conditioning for QTL detected in the primary scan. Virtually all QTL effects detected were 0.5 SD or more. QTL affected age-constant: LW (BTA 9 and 17), CW (BTA 2 and 5), RE (BTA 12), FD (BTA 16), KPH fat (BTA 20), YG (BTA 5 and 16), and MB (BTA 2 and 29). QTL affected weight-constant: DP (BTA 24), RE (BTA 9 and 12), FD (BTA 16), KPH fat (BTA 15 and 20), YG (BTA 12 and 16), and MB (BTA 2, 11, and 29). QTL affected fat-constant: LW (BTA 12,17, 18), DP (BTA 16 and 24), RE (BTA 12), KPH fat (BTA 15, 17, and 20), YG (BTA 12), MB (BTA 2, 14, 18, and 26). Effects were similar in progenies of Line 1 Hereford and CGC females. These results indicate new promising locations for QTL segregating in Bos taurus that affect carcass traits. Greater marker saturation and refined methods for data analysis may lead to precise determinations of QTL.