Evaluation of Soybean Oil as a Lipid Source for Pig Diets

Abstract

An experiment was conducted to determine the effects of soybean oil supplementation replacing tallow in pig diets at different stages of growth. One hundred and twenty crossbred (Landrace x Yorkshire x Duroc) pigs weighing 18 kg on average were selected. Pigs were randomly allotted to 12 pens of 10 pigs (5 pigs of each sex) each. Three pens were assigned to each of the four treatments: TA: tallow diet, TA-SO-80; switched from tallow to soybean oil diet at 80 kg average body weight, TA-SO-45; switched from tallow to soybean oil diet at 45 kg average body weight, and SO; soybean oil diet. Treatment SO was significantly lower in ADG than tallow diets (TA, TA-SO-80 and TA-SO-45) during the grower period (18 to 45 kg). However, treatment SO showed greatest compensation in ADFI and ADG during the finisher-2 period (after 80 kg body weight). ADFI and ADG and Gain/Feed for the total period were not significantly different among treatments. Loin area, back fat thickness, firmness and melting point of back fat were not significantly different. The levels of total cholesterol and low density lipoprotein+very low density lipoprotein cholesterol in serum were significantly lower in treatment SO than in treatments TA-SO-45, TA-SO-80 and TA. The level of serum triglyceride linearly increased as the length of the tallow feeding period increased. Serum immunoglobulin-G (IgG) level was significantly higher in the soybean oil treatment than in other treatments. Major fatty acid composition of short rib muscle and back fat were significantly influenced by treatments. Contents of alpha-linolenic acid (C18:3) and docosahexaenoic acid (DHA, C22:6) linearly increased as the soybean oil feeding period increased. In conclusion. soybean oil can be supplemented to the diet of pigs without significant effects on growth performance and carcass characteristics. The level of polyunsaturated fatty acids (PUFA), especially omega-3 fatty acids in the carcass was increased by soybean oil supplementation.