DIETARY ARGININE REQUIREMENT OF YOUNG RAINBOW-TROUT (ONCORHYNCHUS-MYKISS)

1. Two growth trials were conducted with young rainbow trout (Oncorhynchus mykiss) to determine the dietary arginine requirement under conditions of rapid weight gain at 15-degrees-C. 2. The growth requirement does not exceed 4.2 g arginine/16 g dietary nitrogen and, thus, is much lower than the value of 6.0 g arginine/ 16 g dietary nitrogen presently listed by the NRC for Chinook salmon and widely applied to all Salmonids. 3. Comparison of the present results with the arginine requirement of the chick reveals remarkable similarity despite the phylogenetic distance between the two species, and demonstrates the need to re-evaluate, as anomalously high, the presently-accepted value for Chinook salmon.