Effect of duration of feeding under free-range conditions on production results and carcass and fat quality in Iberian pigs.

This experiment was undertaken to provide information on the effect of feeding system applied during the finishing period (100-150kg) on the quality of Iberian pig meat. Four feeding systems were applied: pigs fed under free-range conditions with acorns and grass fully available during 111 days (FR(111)), pigs fed concentrate diet in confinement during 28 days and free-range with acorns and grass fully available during 83 days (CDC(28)+FR(83)), pigs fed concentrate diet in confinement during 65 days and free-range with acorns and grass fully available during 46 days (CDC(65)+FR(46)) and pigs fed concentrate diet in confinement with a feed average daily amount of 3.1kg during 111 days (CDC(111)). The CDC(111) pigs had more muscular carcasses characteristics than the remaining groups of pigs. However, the higher concentration of C18:1 n-9 in subcutaneous backfat was found in FR(111) pigs. In the neutral lipids from intramuscular fat of Longissimus dorsi only the C18:2 n-6 and C18:3 n-3 proportions were affected by feeding system, and the n-6/n-3 ratio observed was lower in FR(111) and CDC(28)+FR(83) pigs than in CDC(111) pigs. In the neutral lipids from hepatic fat the proportion of n-6 fatty acids was lower in FR(111) pigs than in CDC(65)+FR(46) and CDC(111) pigs.