The effect of selection for intramuscular fat on fatty acid composition in Duroc pigs
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Due to increased demand for pork products with superior meat quality, increased emphasis has been placed on breeding programs that focus on traits that influence meat quality. At the present time, several studies have been conducted to increase marbling (IMF) in pork; however, very few have focused on the health implications that may be associated with selection for increased quantities of IMF. Pigs in the current study that were selected for increased IMF had a greater concentration of saturated fatty acids in both IMF and subcutaneous fat depots. Pigs in the control line had a more unsaturated fatty acid profile and compositionally were leaner. Fatty acid composition of IMF from pork is moderate to highly heritable for total lipids. The greatest heritability estimates were for lauric acid (0.73), palmitoleic acid (0.40), stearic acid (0.36), linoleic acid (0.33) and alpha-linolenic acid (0.26). Heritability estimates for PL and TAG were nearly zero, suggesting that there may not be enough variation in the population to detect a difference in the heritability estimates of these lipid fractions. There were no significant genetic correlations between fatty acids and eating quality traits in the current study. Linoleic acid was positively correlated with LMA (0.75) and negatively correlated with tenth-rib backfat (-0.62). This unique population of pigs allowed for identification of genes associated with IMF concentrations as well as fatty acid composition. The genes investigated in this study and identified to play a role in fatty acid synthesis and interconversion were stearoyl-CoA desaturase (SCD), fatty acid synthase (FASN), and acetyl-CoA carboxylase (ACC). Understanding the changes in fatty acid composition as a correlated response to selection for IMF is more important than direct selection for specific fatty acids.