Oxford University Press, Journal of Animal Science, 7(92), p. 2960-2970, 2014
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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 × 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 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 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 RO, 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 PPARα 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 pigs fed PF, and tended to be less (P = 0.06) than 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 liver triglyceride concentrations of young pigs, accompanying with the upregulation of fatty acid catabolism pathways.