Effect of feeding level and dietary electrolytes on the arginine requirement of rainbow trout ( Salmo gairdneri)

Experiments were conducted to determine the effect of level of feeding (restricted feeding and feeding to satiation) and dietary variations in the balance of monovalent minerals on the arginine requirement of rainbow trout fingerlings. Based on growth and efficiency of feed utilization for growth, the arginine requirement was lower (3.5% of protein) when fish were fed to satiation than when they were fed at a restricted level (4.2% of protein). When calculated on the basis of the amount of arginine consumed per day, however, the requirements were similar for fish subjected to the two methods of feeding. Three balances (acidic, neutral, and alkaline) of sodium, potassium and chloride were used in several experiments. The arginine requirement tended to be higher when fish were fed diets containing the alkaline as compared to the acidic balance of minerals. These studies indicate that the method of feeding has a significant effect on the dietary concentration of arginine needed to maximize growth rate and feed utilization in rainbow trout.