|Tshipuliso, N. O. M.|
Submitted to: South African Journal of Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2008
Publication Date: 4/1/2008
Citation: Tshipuliso, N., Alexander, L.J., Geary, T.W., Snelling, W.M., Rule, D.C., Koltes, J.E., Mote, B.E., MacNeil, M.D. 2008. Mapping quantitative trait loci for fatty acid composition that segregate between Wagyu and Limousin. South African Journal of Science 38(2):126-130. Interpretive Summary: Healthfulness of beef is determined, in apart, by its fatty acid composition. High levels of saturated fat are associated with increased serum low-density lipoprotein cholesterol concentrations and pose a risk factor for coronary heart disease. Fatty acid composition is believed to be under a degree of genetic control. Thus, we conducted a search for places in the genome (QTL) of cattle that harbor genes that affect relative amounts of saturated, monounsaturated and polyunsaturated fatty acids. We found a major QTL with additive effects on fatty acid composition near the centromere of chromosome 2. In addition, we found five less important QT: with dominance effects on fatty acid composition. These results suggest that it may be possible to improve healthiness of beef by manipulating fatty acid composition using genetic markers and appropriate crossbreeding systems.
Technical Abstract: The objective of this study was to search for quantitative trait loci (QTL) that segregate between Wagyu and Limousin and affect relative amounts of saturated (SFA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids. Six F*1 Wagyu-Limousin cross bulls were joined with 121 F*1 females over a three-year period to produce 328 F*2 progeny. Calves, aged from 450 to 641 d (average 561 d), were harvested using standard industry procedures. The wholesale rib was removed from each carcass at 2 d postmortem, vacuum packaged, and aged for 14 d at 2°C. After aging, 2.54 cm thick steaks were cut from the posterior end of the wholesale rib, frozen at -20°C, and held for determination of fatty acid composition. Initially, 156 microsatellite markers covering the 29 bovine autosomes were assayed and QTL were identified by least squares regression. An additional 61 markers were assayed in regions of the genome indicating potentially significant QTL. A genome-wise significant (P < 0.05) QTL with additive effects on SFA (4 cM), MUFA (4 cM) and PUFA (11 cM) was observed on BTA2. In addition, five QTL suggestive of dominance effects were also observed. Based on these results it was concluded that it may be possible to improve healthiness of beef by manipulating fatty acid composition using genetic markers and appropriate crossbreeding systems.