Effect of Diet on Imidazole Compounds and Creatine in Chinook Salmon

Abstract

HALVER^1,2 has recently devised highly purified diets for the Chinook salmon (Oncorhynchus tshawytscha), which have been used to determine the amino-acid and vitamin requirements for this species^2,3. Since the muscle of the salmon contains both free histidine and anserine⁴, it was of interest to determine the content of these imidazole compounds in the muscles of histidine-deficient fish. Samples of these and also of control and methionine-deficient salmon were made available to us through the courtesy of John E. Halver, U.S. Fish and Wildlife Service, Cook, Washington. The weight of the histidine and methionine-deficient fish over a ten-week feeding period was relatively constant at 1.8 gm., whereas the control fish increased in weight from 1.8 to 3.3 gm. The skeletal muscles of four fish in each group were combined and were analysed for histidine, 1-methylhistidine, carnosine and anserine by the ion-exchange method of Davey^4,5, and also for creatine and creatinine by the method of Van Pilsum et al. ⁶. Non-protein nitrogen was determined by micro-kjeldahl. Results are shown in Table 1.