Free range rearing of pigs with access to pasture grazing - effect on fatty acid composition and lipid oxidation products

The influence of free-range rearing, RN genotype and sex on different pig m eat quality traits, including intramuscular fatty acid composition and leve ls of lipid oxidation products, were studied. A total of 60 Hampshire cross bred pigs were reared outdoors for two months with access to green feed, wh ile 60 others were kept indoors, in a 120-m(2)-large pen, throughout the re aring period. From these 120 animals a subsample of 44 animals was chosen f or meat quality analysis. Of the three factors studied, the RN genotype had the largest influence on basic technological meat quality traits, whereas the rearing conditions and sex had limited effects. However, outdoor rearin g resulted in higher levels of polyunsaturated fatty acids in the intramusc ular fat (P = 0.026) and in an increased level of vitamin E (P = 0.030) com pared with the pigs that had been reared indoors. The sex and RN genotype o f the animals also had an effect on the fatty acid profile: females had hig her levels of unsaturated fatty acids (P = 0.003) as well as lower levels o f saturated fatty acids (P = 0.011) than castrated males. Carriers of the R N- allele expressed a higher sum of omega-3 fatty acids (P = 0.047) and C22 :5 (P = 0.012) than did the non-carriers. In a storage study where meat fro m free-range and indoor reared pigs was stored for 3 months at-20 degreesC, it was shown that the lipid oxidation product malondialdehyde was formed a t increased levels in animals that had a higher lean meat percentage than o thers, i.e. females that were carriers of the RN- gene and that were reared outdoors. (C) 2001 Elsevier Science Ltd. All rights reserved.