The energy content of the diet, calculated at 16.7 J/g for protein and carbohydrate, 37.7 J/g for fat is 16.3 J/g. Diet components and chemicals – Purified high nitrogen casein, pure corn starch, Alphacel (non-nutritive bulk cellulose), AIN-76 vitamin mixture, AIN-76 mineral mixture and choline bitartrate (99% pure) was obtained from ICN Nutritional Biochemicals, Cleveland, OH. Imperial brand (Sugarland, TX) extra fine pure cane sugar and 100% pure corn oil (Wesson) were purchased locally. D.L. methionine was purchased from Sigma, St. Louis, MO. Corn oil (CO) contains about 50% linoleic acid, 23% oleic acid, 10% C16 fatty acids and < 1% n-3 PUFAs. The n-3 ethyl ester concentrate of fish oil (FOC) contains >65% n-3 ethyl esters, (>33% EPA, >22% DHA, 10% other n-3 fatty acids), was supplied antioxidant free by Lipromega AS, Norway.