The inclusion of Palmaria palmata macroalgae in Atlantic salmon (Salmo salar) diets: effects on growth, haematology, immunity and liver function: effects on growth, haematology, immunity and liver function

A feeding study was carried out for fourteen weeks to evaluate the effects of partial inclusion of 5, 10 and 15 % of dillisk, Palmaria palmata, into formulated Atlantic salmon (Salmo salar) diets. A further fourth diet was produced without the presence of algae and was used as a basal reference diet. All the four diets were formulated to be iso-nitrogenous (40 %), iso-lipidic (25 %) and iso-energetic (26 MJ kg(-1)). Salmon growth (final body weight, weight gain, feed conversion ratio (FCR), specific growth rate (SGR)) were comparable across algal and control diets, with no significant differences amongst the treatments (P 0.05). Comparisons of liver weight, viscera weight and viscerosomatic index (VSI) also suggested that the macroalgal inclusion did not affect fish growth (P 0.05). Fish health indicators across haematological, immunological and hepatic function were generally similar between the experimental diets. The exceptions to this pattern included a significant decrease in alanine transaminase activity (P 0.05) in the diet with 5 and 15 % P. palmata inclusion compared to other experimental diets. This may indicate that higher P. palmata inclusion improved hepatic function. Seaweed inclusion at 5 % also had positive effects on body lipid content when compared to the control diets. In conclusion, the findings demonstrated that P. palmata can be a suitable feed supplement in Atlantic salmon (S. salar) diets.