At present time, fish feed contains a large proportion of raw materials derived from plants, and salmon that are fed plant protein-based diets may develop obesity related problems. In a NIFES study, groups of salmon were fed diets containing 20 percent fish meal in their feed and the rest of the protein arrived from plant protein., The fishmeal was replaced with 5 to 20 percent predigested (hydrolyzed) fish protein, i.e. protein that had been broken down into smaller molecular components.
This had no effect on feed intake, but growth reduced as the amount of predigested protein increased, says NIFES research scientist Marit Espe.
Gutted fish weights were not different in fish fed hydrolyzed protein diets or the fishmeal based diet, which suggests that salmon fed the predigested fish protein have less intestinal fat, with potentially positive effects on their health. In humans, intestinal fat is regarded undesirable, and this is also likely to be the case in salmon.
Predigested fish proteins are a byproduct of fisheries, so adding them to fish feed means better utilisation of these resources also.
We need to do more research in order to confirm that hydrolyzed fish protein have positive effects on salmon health. We are about to start a project that will look at the effects of fish proteins at a cellular level, says Espe.
The study was carried out on salmon that weighed 400 grams, until they grew to a kilo in the course of 12 weeks.
The study was financed by the Research Council of Norway and Ewos Innovation AS. This report is based on the Article "Hydrolyzed fish protein concentrate (FPC) reduces viscera mass in Atlantic salmon fed plant-protein-based diets, which is published in the December issue of the journal Aquaculture Nutrition.
