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Digestibility of energy and lipids, and metabolic oxidation status in nursery pigs fed various lipids
An experiment was conducted to evaluate the impact of lipid source on energy and lipid digestibility, and on metabolic oxidation status of nursery pigs fed diets containing 10% of soybean oil (SO), choice white grease (CWG), palm oil (PO), or one of two different sources of distillers corn oil (DCO1 and DCO2). Fifty-four barrows weaned at 28-d of age were fed a common starter diet from d 1 to 7, followed by group feeding their respective experimental diets (either 100% basal or 90% basal + 10% test lipid) from d 8 to 14 to adapt the pigs to their dietary treatments and to optimize subsequent feed intake. For the next 10 d (d 15 to 24), pigs were moved to metabolism crates for continued diet adaptation and to become accustomed to the twice daily feeding regimen in the metabolism crates. Following this period, a 4-d total fecal and urine collection occurred (d 25 to 29, final BW 11.03±0.51 kg) to determine apparent total tract digestibility (ATTD) of energy and lipids, and to determine the DE and ME content of each lipid source. After an overnight fast of 12 h, urine was collected for 5 h, quantified, and subsequently analyzed for thiobarbituric acid reactive substances (TBARS) and isoprostane (IsoP) concentration. Following this collection, serum was obtained and analyzed for TBARS. Soybean oil had greatest (P < 0.05) DE (9,388 kcal/kg) content compared with DCO1, DCO2, CWG, PO, and SO containing 8,001, 8,052, 8,531, 8,293, and 9,388 kcal/kg lipid, respectively. Digestible energy as a percentage of GE was greatest (P < 0.05) for SO when compared to the other lipid sources (P < 0.05). The ATTD of EE averaged 85.0% and varied slightly (84.4% to 85.6%) among treatments. Differences in ME among lipids were similar to that for DE, with ME values for DCO1, DCO2, CWG, PO, and SO containing 7,921, 7,955, 8,535, 8,350, and 9,408 kcal/kg lipid, respectively. Metabolizable energy as a percentage of DE did not differ between lipid sources. Pigs fed the diets containing lipids had higher (P < 0.05) plasma TBARS compared to pigs fed the control diet, but no differences were noted in urinary TBARS excretion among treatments. Urinary IsoP excretion differed among treatments (P < 0.01), but was highly variable (34.0 to 104.6 pg/ml). These results indicate that DE and ME values vary among lipid sources and appear to have variable effects on metabolic oxidation measures.
Keywords: digestibility, energy, lipids, pigs