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To evaluate the effect of feeding thermally oxidized vegetable oils and animal fats on growth performance, liver gene expression, and liver and serum fatty acid and cholesterol concentration in young pigs, 102 barrows (6.67 ± 0.03 kg BW) were divided into 3 groups and randomly assigned to dietary treatments in a 4 x 3 factorial arrangement. The main factors were lipid source (n = 4; corn oil [CN], canola oil [CA], poultry fat [PF], and tallow [TL]) and lipid peroxidation level (n = 3; original lipids [OL], slow oxidation [SO] through heating at 95°C for 72 h, or rapid oxidation [RO] through heating at 185°C for 7 h). Pigs were provided ad libitum access to diets in group pens for 28 d followed by controlled feed intake in metabolism crates for 10 d. On d 39, all pigs were euthanized for liver samples to determine liver weight, lipid profile, and gene expression patterns. Lipid oxidation analysis indicated that compared with the OL, SO and RO of lipids had a markedly increased concentrations of primary and secondary peroxidation products, and the increased lipid peroxidation products in CN and CA were greater than those in PF and TL. After a 28-d ad libitum feeding period, pigs fed RO lipids tended to have reduced ADFI (P = 0.09) and ADG (P < 0.05) compared with pigs fed OL, and pigs fed CA had reduced G:F (P < 0.05) compared with pigs fed all other lipids. Pigs fed RO lipids tended to have increased relative liver weight (P = 0.09) compared with pigs fed OL. Liver triglyceride concentration (LTG) in pigs fed OL was greater (P < 0.05) than in pigs fed SO lipids and tended to be greater (P < 0.07) than in pigs fed SO. The reduced LTG were consistent with increased (P < 0.05) mRNA expression of PPARa factor target genes (acyl-CoA oxidase, carnitine palmitoyltransferase 1, and mitochondrial 3-hydroxy-3-methylglutary-CoA synthase) in pigs fed SO and RO lipids compared with pigs fed OL. Pigs fed CN or CA tended to have increased LTG {P = 0.09) compared with pigs fed TL. Liver cholesterol concentration in pigs fed CN was less (P < 0.05) than in pigs fed PF and tended to be less (P = 0.06) than in pigs fed TL, whereas pigs fed CA had a reduced (P < 0.05) liver cholesterol compared with pigs fed PF or TL. In conclusion, feeding thermally oxidized lipids negatively affected growth performance and LTG of young pigs, which was associated with an upregulation of fatty acid catabolism pathways. [ABSTRACT FROM AUTHOR]

Previous research has implicated linseed oil in altering lipid metabolism of dairy cattle when infused intravenously as lipid emulsion. The objective was to determine the effects of abomasal linseed oil (LO) infusion on liver triglyceride (TG) accumulation and subcutaneous adipose tissue lipolysis during fatty liver induction. Eight nonpregnant, nonlactating Holstein cows were randomly assigned to treatments in a replicated 4 x 4 Latin square design. Treatments included abomasal infusion of water (W), tallow (T), LO, or half tallow plus half LO (LOT) at a rate of 0.56 g/kg BW per day for 4 d. Daily treatments were administered directly into the abomasum, divided into 6 doses and administered every 4 h. Infusion of treatments was concurrent with a 4 d fast. Cows were fed ad libitum for 24 d between periods of fasting and lipid infusion. T contained 43% C18:1, 24% C16:0 and 14% C18:0. LO contained 51% C18:3, and 17% C18:2. For most parameters, contrasts were: W vs. LO + LOT + T (effect of lipid), LO vs. T (linear effect of LO), and LOT vs. LO + T (nonlinear dose effect of LO). For measurement of blood fatty acid composition, differences among treatment means were determined using the PDIFF procedure of PROC MIXED. Infusion of linseed oil (LO or LOT) increased α-linolenic acid (g/100 g fatty acid) in serum (P < 0.05) but not in the nonesterified fatty acid (NEFA) fraction of plasma. Treatments had no effect on plasma NEFA concentrations. Infusion of LO increased total serum fatty acid concentration (nonlinear dose effect; P = 0.06). Abomasal infusion of lipid significantly increased isoproterenol stimulated lipolysis by subcutaneous adipose tissue explants in vitro. Liver TG content increased 4.8, 4.9, 2.3 and 2.3 μg TG/ μg of DNA during the fast for W, LO, LOT and T, respectively; infusion of lipid decreased liver TG accumulation (P = 0.06) when compared to W, but this was due to T (LO vs. T; P = 0.03). Abomasal LO infusion failed to reduce liver TG accumulation, plasma NEFA concentration or alter subcutaneous adipose tissue lipolysis. [ABSTRACT FROM AUTHOR]