LIPID-METABOLISM IN PIGS FED BEEF TALLOW OR HIGH-OLEIC ACID SUNFLOWEROIL

The objectives of this study were to establish the effects of high-ole ic sunflower oil (HOSO) and beef tallow on tissue fatty acids and stea royl-CoA desaturase activities in swine; and to compare effects of HOS O and tallow on swine plasma triglycerides and lipoprotein-cholesterol fractions. Sixteen gilts were divided into two groups: eight fed a co ntrol diet containing 10 g/100 g beef tallow, and eight fed a diet con taining 10 g/100 g HOSO. Plasma samples were obtained before feeding b egan and at 4 weeks and 8 weeks of dietary treatment. Samples were obt ained from longissimus dorsi muscle, liver, adipose and duodenal mucos a for the measurement of fatty acid composition and stearoyl-CoA desat urase activity. The HOSO diet increased (P < 0.05) the concentrations (mu mol/g wet weight of tissue) of 18:1 and 18:2 (n-6) in adipose tiss ue. In muscle from pigs fed the HOSO diet, concentrations of 14:0, 16: 0, 16:1, 18:0, 18:1, and 18:2 (n-6) decreased (P < 0.05) relative to m uscle from pigs fed the beef tallow diet; only 14:0 and 16:1 were redu ced in liver by the HOSO diet, Stearoyl-CoA desaturase specific activi ty [(pmol 7 mol(-1) mg(-1) microsomal protein)] was 40 percent lower, and activity expressed as pmol 7 min(-1) g(-1) tissue) was 20 percent lower, in adipose tissue of pigs fed HOSO (P < 0.05). No differences d ue to dietary treatment were observed for desaturase activity from mus cle, liver or intestinal mucose. Plasma triglycerides declined steadil y in the tallow-fed pigs, possibly reflecting the lower percentages of liver 18:0 and 18:1 acids, relative to the HOSO-fed pigs. The animals responded similarly to the addition of fat (beef tallow or HOSO) to t heir diets with increased (P < 0.05) plasma total, LDL- and HDL-choles terol by 4 weeks of treatment. Total cholesterol, LDL-, VLDL- or HDL-c holesterol were not different between pigs fed beef tallow or HOSO. Th us, differences in fatty acid composition of the diets were sufficient to alter tissue fatty acid composition and adipose tissue desaturase activity, but insufficient to alter plasma lipoprotein cholesterol.