Higher dietary micronutrients are required to maintain optimal performance of Atlantic salmon (Salmo salar) fed a high plant material diet during the full production cycle

Abstract

A full life cycle (parr to harvest) study of growth and performance was conducted in Atlantic salmon fed diets high in plant ingredients supplemented with graded levels of a nutrient premix (NP), containing selected amino acids, taurine, cholesterol, vitamins and minerals to re-evaluate current nutrient recommendations. Triplicate groups were fed one of three NP levels included at 1×, 2× and 4×, where 1× corresponds to recommendations of NRC (2011). Whole body and specific tissue concentrations of nutrients were monitored throughout the experiment as requirement markers. Growth in parr was significantly enhanced in 2xNP, but restricted in 4xNP, while in post-smolts growth was positively correlated with NP level. Spinal deformity decreased linearly with increased NP level in both smolt and post-smolts. When fishmeal and fish oil are present at very low levels, as in the present study, we found beneficial effects with moderate increased levels of the B-vitamins niacin, riboflavin and cobalamin. Further, vitamin C should be increased, based on metabolic responses, although it did not influence growth. Increased Zn and Se affected fish metabolism in a positive manner. Alterations in hepatic transcriptome profiles and expression of specific genes of metabolic pathways were evident in response to micronutrient supplementation level. Collectively, increasing the levels of the micro-nutrient package to a too high level, showed a negative effect and cannot be recommended. NRC (2011) recommendations should therefore be revised for diets in which plant ingredients form the major part of the formulation.