In order to determine whether taurine has an effect on cell survival, salmon liver cells were isolated and cultured with minimal amounts of taurine or with a concentration similar to that found in normal salmon liver tissue. The results showed that a larger percentage of the liver cells that were given taurine survived than of those that were not.
“This shows that taurine is important for salmon liver cells, which means in turn that it is also important for salmon health,” says NIFES research scientist Marit Espe.
Farmed salmon feed currently contains more than 50 per cent plant protein. Vegetable raw materials have a quite different amino acid composition from fish meal, and they do not contain taurine. This means that it is important to know about of the potential consequences if salmon feed lacks sufficient taurine, and of the potential impact of such a deficiency on the health of the fish.
“We know that salmon synthesise their own taurine from the essential amino acids methionine and cysteine, but we do not know whether they produce enough to avoid liver damage,” says Espe.
The cell study suggests that taurine ought to be added to plant-based salmon feed. Other studies have shown that a low concentration of the sulphur-containing amino acids methionine and cysteine can lead to problems of obesity, apoptosis (programmed cell death) and poor fish health.
“It is important to be aware of the consequences of taurine deficiency in order to know how much the salmon feed ought to contain,” says Espe.
The study is published in British Journal of Nutrition.