Phenotypic and genetic correlations of fatty acid composition in subcutaneous adipose tissue with carcass merit and meat tenderness traits in Canadian beef cattle
Ekine-Dzivenu, C., Vinsky, M., Basarab, J.A., Aalhus, J.L., Dugan, M.E.R., Li, C. (2017). Phenotypic and genetic correlations of fatty acid composition in subcutaneous adipose tissue with carcass merit and meat tenderness traits in Canadian beef cattle, 95(12), 5184-5196. http://dx.doi.org/10.2527/jas2017.1966
Plain language summary
Beef cattle traits can be improved through genetic selection. However, genetic selection on one trait can lead to changes of other traits depending on magnitude and direction (i.e. favorable or unfavorable) of genetic correlations between traits. Therefore, the most effective way to improve beef cattle traits is to select cattle based on an index (i.e. multiple trait selection index), which considers the economic impact of the traits under selection and their correlations. Beef fatty acid composition, carcass and meat quality traits are economically relevant traits. The purpose of this study was to evaluate how genetic selection of fatty acid composition in subcutaneous adipose tissue of beef cattle will lead to changes in carcass merit and meat tenderness traits based on measures of these traits in 1366 finishing steers and heifers. The results showed that genetic correlations between fatty acids, carcass and meat tenderness were low in general. However, moderate to moderately high genetic correlations were detected and some genetic correlations are not favorable, including genetic correlations of omega-6 and omega-3 fatty acid ratio with overall tenderness (genetic correlation = 0.41) and total conjugated linoceic acids (CLA) with hot carcass weight (genetic correlation = -0.34). These correlations suggest that genetic selection for a lower or healthier omega-6 and omega-3 fatty acid ratio will reduce overall tenderness of beef while genetic selection for a higher or healthier CLA content will compromise hot carcass weight. Due to these unfavorable correlations, multiple trait economic indexes are recommended when genetic improvement on fatty acid composition, carcass merit and meat tenderness traits is considered simultaneously in the breeding program.
Bivariate animal models were used to estimate phenotypic and genetic correlations between 9 carcass merit and meat tenderness traits with 25 individual and grouped fatty acids in the subcutaneous adipose tissue of a population of 1,366 Canadian beef cattle finishing heifers and steers. In general, phenotypic correlations were low (<0.25 in magnitude) except for moderate phenotypic correlations of 9c-17:1 (−0.29 ± 0.16), 18:0 (0.26 ± 0.14), 11c-18:1 (−0.33 ± 0.15), 11t-18:1 (0.35 ± 0.14) with Warner–Bratzler shear force measured 3 d postmortem and between 14:0 (−0.36 ± 0.1), 9c-14:1 (−0.34 ± 0.08), 9c-16:1 (−0.36 ± 0.08), 9c-18:1 (0.26 ± 0.07), and sum of branched-chain fatty acids (BCFA; −0.27 ± 0.06) and back fat thickness (BFAT). Genetic correlations were also low for most of the traits. However, moderate to moderately high genetic correlations (0.25 to 0.50 in magnitude) were detected for some traits, including 17:0 (0.4 ± 0.11), 18:0 (0.44 ± 0.12), 9c-14:1 (−0.47 ± 0.11), 9c-16:1 (−0.43 ± 0.11), and the n-6:n-3 PUFA ratio (−0.5 ± 0.15) with HCW; 9c-14:1 (−0.41 ± 0.13) and 9c-16:1 (−0.42 ± 0.13) with BFAT; ai17:0 (0.43 ± 0.19) and BCFA (0.45 ± 0.19) with lean meat yield; 13c-18:1 (0.40 ± 0.15) with carcass marbling score; sum of CLA (0.45 ± 0.22), 18:2n-6 (0.47 ± 0.17), and sum of PUFA (0.48 ± 0.17) with overall tenderness measured 3 d postmortem; the n-6:n-3 PUFA ratio (0.41 ± 0.22) and sum of CLA (0.42 ± 0.25) with overall tenderness measured 29 d postmortem; and BCFA (0.41 ± 0.27) with Warner–Bratzler shear force measured 29 d postmortem. The genetic correlations observed in this study suggest that contents of some fatty acids in beef tissue and carcass merit and meat tenderness traits are likely influenced by a subset of the same genes in beef cattle. Due to some antagonistic genetic correlations, multiple-trait economic indexes are recommended when fatty acid composition, carcass merit, and meat tenderness traits are included in the breeding objective.