Rainbow trout, fed or starved for 5 weeks, were force-fed 23 μCi 1-14C-palmitic acid and sacrificed at [Formula: see text], 1, 2, 4, 8, and 14 h after feeding. Analysis of the blood suggested that trout possess an intestinal absorption mechanism for lipid that is very different from that found in other animals. The fish, incapable of delivering triglyceride to its circulation in the usual way, receives most of its absorbed lipid as free fatty acids, probably via the portal system. It was also found that light muscle more easily yielded its triglyceride stores, in agreement with its role as the major lipid depot in trout. Nonetheless, dark muscle was metabolically more active in deposition of muscle lipids. Dark muscle appeared to function more as an organ than a kinetically responsible contractile body.

No abstract