Biochemical and gene expression differences associated with higher fat deposition in Krškopolje pigs in comparison with lean hybrid pigs

Abstract

Krškopolje pig is the only preserved local pig breed in Slovenia. Compared to lean pig genotypes, it is characterised by greater capacity for lipid deposition. The underlying mechanisms responsible for a greater fat deposition in this breed have not yet been investigated. Therefore, the main objective of the present study was to determine differences in gene expression and lipid metabolism between Krškopolje pigs and lean hybrid pigs reared in the same environmental conditions. Despite a greater fat deposition, activities of lipogenic enzymes were lower in Krškopolje than in lean hybrid pigs (i.e. malic enzyme and glucose-6-phosphate dehydrogenase displayed 2.6- and 2.0-fold lower activity measured on tissue postmortem, respectively). Krškopolje pigs had also lower polyunsaturated fatty acid (PUFA) and higher saturated (SFA) and monounsaturated fatty acids (MUFA) content than their lean-type peers. Consistent with a higher MUFA, overexpression of the stearoyl-CoA desaturase gene was determined in Krškopolje pigs compared to the lean hybrid pigs. In accordance with higher adiposity, Krškopolje pigs exhibited higher expression of genes involved in lipogenesis (ACACA, FASN), adipogenesis (PPARγ) and energy homeostasis (LEP) than lean hybrid pigs. Regarding the sex effect in Krškopolje pigs, females exhibited higher lipogenic enzyme activities than surgically castrated males, while no significant differences were observed for fat quantity and quality traits or gene expression. In conclusion, Krškopolje pigs are characterised by a higher fat deposition associated with higher SFA and MUFA content, a higher expression of genes involved in lipogenesis, and lower activity of lipogenic enzymes compared to lean-type hybrid pigs.