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Lipid digestibility and energy values of corn and soybean oil containing varying levels of free fatty acids (FFA) in nursery pigs
Two experiments were conducted to evaluate the impact of FFA in soybean oil (SO), corn oil (CO), or distillers corn oil (DCO) on the lipid’s subsequent DE, ME, and ether extract (EE) digestibility. Two groups of 54 pigs weaned at 28 d of age were fed a common starter diet for from d 1 to 7, followed by feeding groups their respective experimental diet (either 100% basal or 90% basal + 10% test lipid) from d 8 to 14. For the next 10 d (d 15 to 24) pigs were moved to individual metabolism crates for continued diet adaptation and to become accustomed to twice daily feeding regimen and being housed in metabolism crates. Total fecal and urine collection occurred on d 25 to 29 to determine total tract energy and lipid digestibility. Final BW and ADFI was 13.3 kg and 450 g for Exp. 1 and 15.8 kg and 500 g for Exp. 2, respectively. Diets consisted of SO and SO FFA, with or without 6% lecithin, (Exp. 1), or CO containing 0 or 95% FFA, or DCO containing 5, 10, or 15% FFA (Exp. 2). In Exp. 1, adding lecithin interacted with FFA level, reducing DE, DE as a percentage of GE, and ME in SO FFA, but not in SO (P < 0.01). Lecithin had no effect on ether extract (EE) digestibility, while feeding SO FFA reduced EE digestibility compared with SO (P < 0.01). Neither FFA level nor lecithin addition affected ME as a percentage of DE. In Exp. 2, pigs fed CO FFA had similar DE, EE digestibility, ME, and ME as a percentage of DE as CO, even though DE as a percentage of GE was higher in CO FFA than for CO (P < 0.05). Increasing levels of FFA in DCO reduced DE, DE as a percentage of GE, and ME (P < 0.05), but had no effect on EE digestibility or ME as a percentage of DE. These results indicate that FFA in SO or CO have little effect on EE digestibility or subsequent DE and ME values, while increasing concentrations of FFA in DCO reduces EE digestibility and subsequent DE and ME values.
Keywords: digestibility, distillers corn oil, energy, free fatty acids, nursery pigs