Selectively bred juvenile F2 amago salmon Oncorhynchus masou ishikawae fed a low fishmeal diet exhibit growth comparable to unselected juveniles fed a fishmeal-based diet

Abstract

Juvenile amago salmon Oncorhynchus masou ishikawae selectively bred for two generations based on growth with a low fishmeal diet and unselected juveniles reared for two generations on a commercial fishmeal-based diet, both originating from the same broodstock pairs, were used in this study. Juvenile salmon (initial weight, 8.4 g) were fed a low fishmeal diet without amino acid supplementation (LFM), a low fishmeal diet with lysine and methionine supplementation (AA) and a fishmeal-based diet (FM) for ten weeks. Growth of the selected group fed diet AA was comparable to the unselected group fed diet FM. The feed efficiency ratio in the selected groups was significantly higher than in the unselected groups. The feed intake of fish receiving the low fishmeal diets was significantly higher in the selected group than in the unselected group. Physiological conditions such as blood hemoglobin concentration, hepatosomatic index, biliary bile acid concentration and distal intestine and liver morphologies were also improved to some extent in the selected groups relative to the unselected groups, but they were still inferior to fish fed the FM diet. These results indicate that selective breeding for growth on a low fishmeal diet is an effective method for solving the problem of limited fishmeal supply and high fishmeal cost.