Effects of increasing dietary oil inclusion from different sources on growth performance, carcass and meat quality traits, and fatty acid profile in genetically lean immunocastrated male pigs

A total of 96 genetically lean immunocastrated male pigs were used in a 98-day study to evaluate the effects of including 3% soybean oil (SO), canola oil (CO), or fish oil (FO) in the diets vs. feeding a standard commercial diet with 1.5% SO (control) on growth performance, carcass and meat quality traits, consumer acceptability, and intramuscular fatty acid composition of the longissimus lumborum (LL) muscle. Pigs were blocked by initial body weight (BW; 28.44 ± 2.95 kg) and assigned to one of four treatments, with six replicate pens per treatment and four pigs per pen. Pig BW and pen feed disappearance were recorded weekly. At the conclusion of the study, pigs were slaughtered, carcass characteristics were measured, and a sample of the LL was removed for meat quality assessment, fatty acid composition analysis, and overall liking evaluation. Dietary treatments had no effect on overall growth performance and pig carcasses. Although loins from pigs fed diets containing either 3% SO or CO had decreased (P = 0.05) Warner-Bratzler shear force, only the addition of 3% SO to pig diets resulted in loin chops that were rated higher (P < 0.001) for consumer overall liking. Adding either 3% SO or CO increased (P < 0.01) the percentages of oleic acid and total monounsaturated fatty acids in the LL intramuscular fat compared to control- or FO-fed pigs. However, intramuscular fat from 3% SO- or CO-fed pigs had the lowest (P < 0.01) proportion of total omega (n)-3 polyunsaturated fatty acids (PUFA) than control- or FO-fed pigs. Including 3% oil, regardless of source, reduced (P < 0.01) total PUFA, total n-6 PUFA, and PUFA:saturated fatty acid (SFA) ratio than control-fed pigs. Dietary FO inclusion decreased (P < 0.01) n-6:n-3 PUFA ratio, but also increased total SFA (P < 0.01) and atherogenic index (P = 0.02) in the LL intramuscular fat. These results indicate that feeding genetically lean immunocastrated male pigs with diets containing 3% FO provided a healthier fatty acid profile in the loins, with the highest content of n-3 PUFA and the lowest n-6:n-3 PUFA ratio; however, pork quality that resulted in greater consumer acceptability was achieved when immunocastrated male pigs were fed 3% SO.