Studies on the utilization by rainbow trout (Salmo gairdneri Rich.) of feed mixtures containing soya bean meal and an addition of amino acids

This paper deals with the growth of fish and utilization of feed mixtures in which fish meal is partly substituted by powdered soya beans. In order to improve the quality of protein in the feeds, they were enriched with synthetic amino acids. The food coefficients of the feeds were calculated, as were the protein efficiency ratio and apparent net protein utilization, by chemical analysis.

The results of the experiment showed that an addition of amino acids improved the utilization of feeds. It was found that rainbow trout can utilize soya bean protein enriched with cystine (1%) and tryptophan (0.5%) almost as well as protein from the fish meal.

Chemical composition of the experimental fish is discussed, as well as the amino acid composition of fish muscles and selected physiological parameters: haematocrit, haemoglobin content in the fish blood, the hepasomato index, and the content of protein, amino-transferases and cholesterol in the fish blood serum.