Dietary nitrogen and lipid utilization by growing pigs fed structured triacylglycerides synthesized from medium-chain triacylglycerides and menhaden oil.

A total of 24 crossbred barrows were used in a 19-d metabolism trial to determine the effect of dietary structured triacylglycerides synthesized by the random reesterification of medium-chain triacylglycerides (MCT) and menhaden oil on growth performance, nitrogen retention, and apparent digestibilities of nitrogen, lipid, and fatty acids. Pigs were randomly assigned to four dietary treatments differing only in lipid source. Dietary treatments (percentage by weight of total lipid) contained either 1) corn oil: soybean oil:MCT oil (40:10:50), 2) MCT oil:menhaden oil (60:40 as structured triacylglyceride), 3) MCT oil: menhaden oil (60:40 nonstructured, physical mixture), or 4) structured triacylglyceride (as in 2): safflower oil:canola oil (80:10:10). Total fecal and urine collections were conducted during two 5-d periods. Apparent nitrogen digestibility and nitrogen retention were high (> 95%) and not affected (P > .05) by dietary treatment. Apparent fatty acid digestibilities were affected by dietary lipid source. Palmitic and arachidonic acid digestibilities were lower (P < .05) for Diet 1, heptadecanoic acid digestibility was elevated by 21% (P < .05) for Diet 2 relative to Diet 3, and stearic acid digestibility was highest (P < .05) for Diet 1, followed by Diets 2, 3, and 4 in decreasing order. This study demonstrates that the physical nature of the lipid (structured vs nonstructured) affects fatty acid digestibility patterns in the growing pig. Further evaluation of MCT/menhaden oil structured triacylglyceride is needed.