Effect of increasing amounts of a linoleic-rich dietary fat on the fat composition of four pig breeds. Part III: Triacylglycerol composition in muscle and fat tissues

Here, we study the triacylglycerol (TAG) profile of four different tissues of the pig (backfat, abdominal fat, and muscles trapezius and longissimus thoracis et lumborum). For this purpose, 48 pigs of four breeds (Landrace, Large White, Duroc and a crossbreed Landrace × Duroc) were given one of four diets containing increasing amounts (0%, 2%, 4% and 8%) of a fat blend rich in linoleic acid. The effects of dietary fat and breed on TAG were tested separately for each tissue, and the results are presented using five TAG composition markers, PLL, PStO, PStL, PStSt and OOO. The increasing linoleic acid content provided by diets 1-4 showed a positive effect on the levels of TAG related to this dietary supply (here represented by PLL), and on those of PStL. This increase was at the expense of TAGs containing mainly fatty acids from de novo synthesis (represented by PStO) and in PStSt and OOO. A comparison of the relative % of change for the five selected TAG markers in the distinct tissues indicates that PLL and PStL show much higher increases in muscle than in adipose tissues, whereas PStO and PStSt show similar percentages of decrease in all tissues. OOO showed a higher % of decrease only in trapezius. Results indicate that the breed has a null or scarce effect on the levels of PLL and PStO. For the remaining TAG markers, Large White showed a higher synthesis of saturated TAG (PStSt and PStL) in fat tissues, but not in muscle. Large White also had the lowest levels of OOO in all tissues, being the breed most susceptible to the changes in dietary linoleic acid content. Moreover, the Landrace showed enhanced deposition of monounsaturated TAG in trapezius muscle and abdominal fat.