Effects of dietary trimethylamine on the concentration of trimethylamine oxide in various tissues of the chum salmon, Oncorhynchus keta, in freshwater and sea-water environments

Abstract

1. 1. Young chum salmon were given one or other of three diets that differed in TMA contents for 4 weeks in freshwater and for 3 weeks in sea-water after 2 weeks adaptation for sea-water. 2. 2. The growth of fish fed on the TMA I diet (TMA 17 mg/100 g) was greater than that of fish fed on the TMA II diet (TMA 171 mg/100 g). 3. 3. TMA and TMO concentrations in the various tissues of the fish were determined. The concentrations of TMA and TMO in the various tissues were influenced by the dietary TMA level and environmental sea-water. 4. 4. The freshwater, fish fed on the TMA I diet had higher TMA and TMO levels in the whole body, muscle and kidney than fish fed on the basal diet or the TMA II diet. 5. 5. Also, in sea-water, the TMA I diet enhanced the accumulation of TMA and TMO in the whole body, muscle, liver and kidney. 6. 6. The levels of TMO in the tissues such as the liver and kidney were increased by feeding TMA I diet, and those increases were higher in sea-water than in the freshwater environment. 7. 7. NPN levels in either freshwater or sea-water fish did not differ greatly between the diets. Except for the whole body and muscle slightly higher values were found in sea-water than in freshwater fish.