Feeding of rainbow trout [Oncorhynchus mykiss] with non-fish meal diets

As a part of the on-going efforts to increase the use of alternative proteins in practical fish feeds, this study was conducted to investigate whether or not fingerling rainbow trout Oncorhynchus mykiss can grow normally on the same non-fish meal diets that resulted in the green-liver for yellowtail. Two feeding experiments were carried out with fingerling rainbow trout for 20 weeks. The first experiment was conducted to examine the effect of supplemental crystalline amino acids, with or without coating, in the non-fish meal diets on the growth performance of rainbow trout. In the second, the effect of supplemental levels of crystalline amino acids in the non-fish meal diets was investigated. Feeding of non-fish meal diets for 20 weeks produced excellent growth and feed performances for rainbow trout without any abnormalities. Supplementation of essential amino acids (EAA) in the non-fish meal diets to balance amino acid profiles comparable to the control fish meal diets resulted in no further enhancement of growth over the control fish meal diet group. The experimental fish could grow well on the non-fish meal diets without EAA supplement. This has shown that the content of EAA in the non-fish meal diets used in this study was sufficient to satisfy the EAA requirement of rainbow trout.