Effect of different dietary lysine level on the functioning of genes participating in buildup of intramuscular fat in pork

The eating quality of pork, e.g. its taste and tenderness are favourably affected by inter- and intramuscular fat (IMF) content. Many genes are involved in forming the fat deposited in the meat and especially in between the muscle fibres, among others, the genes of the FABP family (FABP3, FABP4), the LEPR gene, the SDC and the FASN. The objective of this trial was to study whether a moderate change in dietary Lys content (approximately 6%) through the growing and fattening period results in a shift in the expression of genes involved in fat metabolism (FABP3, FABP4, LEPR, SDC and FASN). In the study, Danbred pigs were assigned from a fattening study that involved 96 pigs (50-50% barrows and gilts) from about 25 kg to 125kg live weight. The animals received three-phase feeding and the feeds were formulated according to their requirements. The dietary treatments were set by diets containing different Lys levels in all phases: 10.9, 9.1 g/kg, and 8.3 g/kg vs 11.5, 9.6 and 9.0 g/kg Lys, respectively. The pigs were slaughtered in 125 kg live weight and carcass classification through lean meat % was performed. Meat samples from the carcass were taken within 30 minutes post-mortem from the longissimus dorsi muscle. Gene expression levels were quantified using RT-qPCR analysis. The results indicated that variations in dietary lysine (Lys) content did not significantly influence slaughter quality or the expression levels of genes associated with fat metabolism. Consequently, it can be inferred that a 10% difference from the recommended Lys content does not alter lipid synthesis in the longissimus dorsi muscle of pigs.