The effect of dietary fatty acid composition on adipose tissue quality and expression of genes related to lipid metabolism in porcine livers

This study investigated different fatty acid profiles in dietary fat sources for pigs fed with corn DDGS (CDDGS) and determined their effect on adipose tissue quality and the expression of metabolism-related genes in the liver. The experiment was carried out on 32 fatteners (60-118 kg of body weight) divided into four groups. Group I (control): feed mixture with rapeseed oil; Group II: feed mixture with rapeseed oil and CDDGS; Group III: feed mixture with beef tallow and CDDGS; Group IV: feed mixture with coconut oil and CDDGS. The results confirmed the relationship between dietary fatty acid profile and acid content in fat tissue. CDDGS reduced SFA/UFA ratios and increased iodine values (P < 0.001) and TBA-RS in the subcutaneous adipose tissue of backfat. Replacing rapeseed oil in a diet including CDDGS with beef tallow or coconut oil enabled the pigs to accumulate more SFA in backfat and reduce iodine value. The genes selected in the present experiment, and which are believed to be associated with lipid metabolism, had been identified as DEGs (differentially expressed genes) in an RNA sequence experiment performed previously to explore the coexpression of these genes after different diets. Expression of the genes, evaluated by Real-Time q-PCR, was not affected in any case by the pig's sex. The expression levels in liver tissue for genes APOA4, ACSL5, CYP2C49, CYP2B22, and GSTO1 were significantly different among groups, while for CYP7A1 the differences identified by RNA sequencing were not confirmed. The expression levels of estimated genes were correlated with the fatty acid profile in a diet, but not with fattening performance results or carcass quality traits. To summarize, CDDGS included in feed mixtures can negatively influence subcutaneous adipose tissue traits important for processing and shelf-life. Dietary factors, such as fat sources characterized by a high degree of saturation, improved the hardness and oxidative stability of the backfat. The fatty acid profile of dietary fat sources affected the expression levels of genes associated with lipid metabolism in the liver. Coconut oil and beef tallow increased the expression levels of genes ACSL5, APOA4, GSTO1, CYP2B22, and CYP2C49. Moreover, most of the genes were co-expressed within the diet, which suggests the possibility of their co-regulation. Further studies will be conducted on metabolic pathways in which the analyzed genes are involved to understand the molecular mechanisms of their activity and possible health effects of their overexpression.