The inclusion of Palmaria palmata macroalgae in Atlantic salmon (Salmo salar) diets: 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