Validity of fish triglyceride content and liver glycogen content as indicators of nutritional status in chum salmon Oncorhynchus keta fry
2020
Torao, M. (Salmon and Freshwater Fisheries Research Institute, Hokkaido Research Organization, Eniwa, Hokkaido (Japan))
Changes in triglyceride (TG) and phospholipid (PL) content in fish body, and glycogen (GC) content in liver of chum salmon Oncorhynchus keta fry during fasting and refeeding treatments were examined for their validity as nutritional status indicators. TG content and TG/PL ratio linearly increased or decreased in relation to fasting and refeeding days. On the other hand, GC content reacted more rapidly. The change in PL content was small and decreased relative to fed controls after 20 days. Fasting until the third day results in GC consumption, followed by TG consumption. After the 20th day of fasting, lipids are almost all consumed, and energy may have been obtained by digestion of body tissues. These results suggest that the TG content in the fish body is suitable for evaluating the nutritional status of salmon fry after release.
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