Influence of long-term nutrition with different dietary fats on fatty acid composition of heavy pigs backfat

The aim of this study was to assess the influence of long-term fat supplementation on the fatty acid profile of heavy pig adipose tissue. Fifty-four Large White barrows, averaging 25 kg LW, were randomized (matched weights) to one of three isoenergetic diets supplemented with either tallow (TA), maize oil (MO), or rapeseed oil (RO). The fats were supplemented at 3% as fed from 25 to 110 kg LW, and at 2.5% from 110 kg to slaughtering. Following slaughter at about 160 kg LW, backfat samples were collected from ten animals per treatment and analyzed. Fatty acid composition of backfat closely reflected the fatty acid composition of the supplemented fats. The backfat of pigs fed TA had the highest saturated fatty acid content (SFA) (P<0.01); those fed MO had the highest content in polyunsaturated fatty acid (PUFA) and the lowest in monounsaturated fatty acid (MUFA) content; those fed RO had the highest content of linolenic acid (C18:3) and cis 11-ecosenoic acid (C20:1). Only MO treatment had an effect on linoleic acid levels and the iodine value (IV) of backfat, resulting in levels higher than those (IV = 70; C18:2 = 15%) accepted by the Parma Consortium for dry-cured ham. The IV and unsaturation index in both layers of subcutaneous backfat tissue differed significantly between treatments. These results show that long-term dietary supplementation with different fats changes the fatty acid profile of heavy pig adipose tissue. Supplementation with rapeseed oil increases the proportion of "healthy" fatty acids in pig fat, thereby improving the nutritional quality, however the effects on the technological quality of the fat must be carefully assessed.