EFFECTS OF DIETARY LEVELS OF CARBOHYDRATE AND LIPID ON GLUCOSE-OXIDATION AND LIPOGENESIS FROM GLUCOSE IN RAINBOW-TROUT, ONCORHYNCHUS-MYKISS, REARED IN FRESH-WATER OR IN SEAWATER

Carbon dioxide production and lipogenesis from U-C-14-glucose were studied in vivo in trout fed three experimental diets varying in their carbohydrate-to-lipid ratio (26/6, 24/10, 21/14) and grown either in freshwater or in seawater. (CO2)-C-14 production from U-C-14-glucose, was higher with the intermediary diet in trout reared in seawater. Lipogenesis from U-C-14-glucose increased with increasing dietary carbohydrate-to-lipid ratio, particularly for the phospholipids, triacylglycerols and fatty acids, but this effect varied according to rearing conditions. The results indicate that dietary regulation of lipogenesis in trout has some similarities with that observed in homeotherms and that salinity and/or fish weight interacts with this regulation.