Genotype with nutrition interaction on fatty acid composition of intramuscular fat and the relationship with flavour of pig meat

The effects of genotype, diet and the genotype with diet interaction on fat ty acid composition of neutral lipid and phospholipid of intramuscular fat in pigs were examined. Pigs from four selection lines and a control line we re fed isoenergetic diets, which differed in ileal digestible lysine:digest ible energy (A: 0.40, C: 0.76 and E: 1.12 g lysine/MJ DE). The selected lin es resulted from seven generations of selection for high daily food intake (DFI), lean food conversion ratio (LFC) and lean growth rate on ad-libitum (LGA) or restricted feeding regimes in a Large White population. During per formance test, from 30 to 90 kg, pigs were fed on either ad-libitum or rest ricted (0.75 g/g ad-libitum daily food intake) feeding regimes. A trained s ensory panel assessed intensities of pork flavour and abnormal flavour and the hedonic characteristics of flavour liking and overall acceptability. Th e proportion of neutral lipid in the LGA line was lower (0.64 V 0.75, s.e.d . 0.03) while the polyunsaturated:saturated (P:S) ratio of the LFC line (0. 53 v 0.41, s.e.d. 0.05) was higher than the control line and other selectio n lines. The DFI line had a higher phospholipid n-6:n-3 ratio than other se lection lines (14 v 11, s.e.d. 1.0). Diets C and E resulted in lower neutra l lipid:phospholipid ratio (0.7 v 0.8, s.e.d. 0.91), n-6:n-3 ratios for bot h neutral lipid (5 v 13, s.e.d. 0.8) and phospholipids (7 v 20, s.e.d. 0.6) and a higher P:S ratio (0.5 V 0.3, s.e.d. 0.03) for neutral lipid than die t A. Neutral lipid fatty acids C18:2 n-6, C18:3 n-3, C20:3 n-6, C20:4 n-6, C20:5 n-3, C22:5 n-3 and C22:6 n-3 were negatively correlated with pork fla vour (-0.30, s.e.d. 0.10), flavour liking (-0.33) and overall acceptability (-0.30). In contrast, the fatty acids C16:1, C18:1 omega 9 and C18:1 omega 11 were positively correlated with pork flavour (0.36), flavour liking (0. 39) and overall acceptability (0.40). However, correlations for fatty acids in the phospholipid class were positive for C18:2 n-6, C20:4 n-6 and C22:4 n-6 with pork flavour (0.33), flavour liking (0.23) and overall acceptabil ity (0.23). The proportion of neutral lipid had non-significant correlation s with flavour traits; pork flavour (0.01), abnormal flavour (0.08), flavou r liking (-0.03) and overall acceptability (0.03). The selection lines resp onded in a similar manner to the different diets, such that there was littl e evidence for genotype with nutrition interactions for fatty acid concentr ations of neutral lipids and phospholipids. Selection for high lean growth will reduce intramuscular fat, but the increased relative amount of phospho lipid and concentration of polyunsaturated fatty acids are unlikely to redu ce eating quality. Nutritional effects on intramuscular Fat characteristics were greater than genetic effects, such that nutritional approaches to fee ding pigs will provide effective methods of reducing the n-6:n-3 fatty acid ratio of human dietary fat from pigmeat and improving human health. (C) 20 00 Elsevier Science Ltd. All rights reserved.