Background and methodology
The fatty acid (FA) composition of porcine intra muscular fat (IMF) has been shown to be affected by feed composition. It is generally known that the FA composition of tissue changes with increasing total lipid content, due to the smaller contribution of polar lipids in total fat. The objective of this study was to investigate the effects of organic and conventional feed, with regard to different dietary n-6/n-3 ratios, on the FA composition of neutral and polar lipids in muscles of female and castrated male pigs. The study was conducted in pigs reared in an indoor environment. Pigs were fed two different diets, one conventional and one organic. The FA composition of different lipid classes correlated with carcass fatness and proportions of lean meat.
Dietary n-6/n-3 ratio influenced the muscle n-6/n-3 ratio of polar and neutral lipids. No general differences in carcass or IMF were evident between the two feeds. Pigs fed conventionally had higher levels of neutral lipids 18:3 n-3 (P=0.001) and PUFA n-3 (P=0.001) and higher levels of 18:3 n-3 (P=0.001) and of PUFA n-3 (P=0.001) in the muscle polar lipids. By contrast, pigs fed organically had higher 18:2 n-6 (P=0.004) and PUFA n-6 (P=0.001) in the polar lipids. The difference in PUNFA n-6 and PUFA n-3 fatty acids also caused higher n-6/n-3 ratios in both polar and neutral lipids of pigs fed organically. Malondialdehyde (MDA) did not differ between dietary regimes.
Högberg, A., Pickova, J., Andersson, K. & Lundström, K. (2003). Fatty acid composition and tocopherol content of muscle in pig fed organic and conventional feed with different n6/n3 ratios, respectively. Food Chemistry 80:177-186.