Effects of pig dietary omega6/ omega3 ratio on fatty acid profiles and nutritional indices of lipid depots

Pork products show an unfavourable n-6/n-3 polyunsaturated fatty acid (PUFA) ratio. Also due to their high level in saturated fatty acids (SFA), pork consumption has been associated with an increased risk of chronic diseases. Enrichment of pig diets with n-3 PUFA is seen as a sound strategy to increase their intake in human diets. Thus, this study investigated the effects of gender and dietary n-6/n-3 PUFA ratio (PR) on the fatty acid (FA) composition and nutritional indices of lipids in subcutaneous (SF) and perirenal (PF) adipose tissues (ATs) and in the longissimus dorsi muscle (LD) of pigs. To this aim 24 pigs, balanced for gender and weight, were assigned either to the control (C) or low PR (LPR) group. The C pigs received a barley/soybean-basal diet, while in the LPR group 5% of barley was replaced with extruded linseed, as a source rich in n-3 PUFA. Dietary PR was 9.7 and 1.4 for C and LPR group respectively. The diets were administered for 104 days, from an initial starting live body weight (LBW) of 80 kg and till slaughter at 151 kg LBW. After slaughter, LD samples were analyzed before and after cooking for malondialdehyde content. Further, the FA composition and nutritional indices such as unsaturation (UI), peroxidizability (PI), hypercholesterolemic (HI), hypocholesterolemic (hI), health-promoting (HPI), nutritive value (NVI), atherogenic (AI) and thrombogenic (TI) indices were determined in the LD and both ATs. LPR group showed overall higher values in PUFA content, in particular n-3 PUFA level, due mainly to α-linolenic acid (ALA) and a lower n-6/n-3 PUFA ratio in LT and in both ATs. However, the higher level of unsaturation did not influence the oxidative stability of both raw and cooked meat. In the LD, LPR group led to a decrease of TI without affecting the other nutritional indices, whereas the gender exerted no effect. Instead, in both ATs these indices were greatly modified in the LPR group and, PI apart, were all improved. Gender exerted a moderately significant effect, showing better values in PF of barrows. It is concluded that feeding linseed to pigs at 5% level in the diet to reduce PR did not have an adverse effect on the oxidative stability of meat while it contributed to the increase of n-3 fatty acids levels in all tissues examined, improving most nutritional indices, especially in ATs, and this could bring about a positive effect on human health.