Due to scarcity of fishmeal, which contains high levels of the sulphuric amino acid taurine, today’s grow-out feed for Atlantic salmon contains up to 50 % plant protein.

Taurine is absent in plant proteins and salmons might be short in taurine when fed such diets.

Research at NIFES shows that salmon synthesizes taurine from ‘vegetable’ diets when levels of the amino acids methionine and cystein are sufficient. Taurine is synthesized from these two amino acids.

Feed trial
In a feed trial this was confirmed. "When the requirement for methionine was met, methionine in excess was converted into taurine," says Marit Espe at the Aquaculture Nutrition Research Programme at NIFES.

According to Espe salmons fed diets with low taurine plant protein based diets have the ability to produce sufficient amounts of taurine assuming that it is supplied with enough methionine. If the feed also contains cysteine, the need for methionine is lower than previously thought.

Recommended levels of methionine for Atlantic salmon range from 2.2 to 2.3 grams of methionine/100gram protein in the grow-out feed.

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