DIETARY NITROGEN AND LIPID UTILIZATION BY GROWING PIGS FED STRUCTUREDTRIACYLGLYCERIDES SYNTHESIZED FROM MEDIUM-CHAIN TRIACYLGLYCERIDES ANDMENHADEN OIL

A total of 24 crossbred barrows were used in a 19-d metabolism trial t o determine the effect of dietary structured triacylglycerides synthes ized by the random reesterification of medium-chain triacylglycerides (MCT) and menhaden oil on growth performance, nitrogen retention, an a pparent digestibilities of nitrogen, lipid, and fatty acids. Pigs wee randomly assigned to four dietary treatments differing only in lipid s ource. Dietary treatments (percentage by weight of total lipid) contai ned either 1) corn oil: soybean oil:MCT oil (40:10:50), 2) MCT oil:men haden oil (60:40 as structured triacylglyceride), 3) MCT oil: menhaden oil (60:40 nonstructured, physical mixture), or 4) structured triacyl glyceride (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 no t affected (P > .05) by dietary treatment. Apparent fatty acid digesti bilities were affected by dietary lipid source. Palmitic and arachidon ic 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 Di et 1, followed by Diets 2, 3, and 4 in decreasing order. This study de monstrates that the physical nature of the lipid (structured vs nonstr uctured) affects fatty acid digestibility patterns in the growing pig. Further evaluation of MCT/menhaden oil structured triacylglyceride is needed.