Utilization of fish silage by rainbow trout ( Salmo gairdneri)

Abstract

The apparent digestibility and utilization of fish protein subjected to the ensilaging process were compared with fish meal in dry diets fed to rainbow trout ( Salmo gairdneri). During the ensilaging process, a majority of the proteins were converted to peptides, a portion of which was further hydrolyzed to free amino acids. Although apparent digestibility values were higher for the fish silages than for fish meal, the fish silages were not as efficiently utilized for growth. Whole fish and fish processing wastes were found to be equivalent sources of nitrogen provided the degree of autolysis was the same and the diets were otherwise nutritionally balanced. Autolysis was reduced and growth rates enhanced when the ingredients were stored at −5°C prior to ensiling.