A full factorial design to investigate interactions of variable essential amino acids, trace minerals and vitamins on Atlantic salmon smoltification and post transfer performance

Katerina Kousoulaki,Aleksei Krasnov,Elisabeth Ytteborg,John Sweetman,Mona Elisabeth Pedersen,Vibeke Høst,Richard Murphy

doi:10.1016/j.aqrep.2021.100704

Katerina Kousoulaki, Aleksei Krasnov + Show 5 more

Open Access

https://doi.org/10.1016/j.aqrep.2021.100704

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Journal: Aquaculture Reports	Publication Date: Apr 27, 2021
Citations: 7	License type: cc-by

Affiliation: Nofima, Alltech (Ireland)

Abstract

To contribute in knowledge for the development of safe, efficient and sustainable functional salmon diets, we ran a feeding trial applying a 23 full factorial design to investigate combined effects, on Atlantic salmon smoltification and post transfer performance, of variable supplementation levels of essential amino acid (Lys, Met, Thr and Arg), essential trace mineral (Zn, Fe and Se) and vitamins (E, C and astaxanthin as provitamin A) premixes in low fishmeal diets, using crystalline amino acids, organic trace minerals and synthetic vitamins, respectively. The nutrient levels used in our study were chosen to meet the known requirements of fish reflecting the variation in commercial feeds. Fish performance, nutrient digestibility, skin, and intestinal health were evaluated in Atlantic salmon parr-smolt, the latter by means of qPCR, global transcriptomics, and immunohistochemistry. The results revealed the potential for significant improvement of salmon post smoltification growth by simultaneous dietary level increase of Met, Lys, Thr and Arg (5% higher body weight increase). Significantly negative effect on fish post transfer growth and survival (22.5 % lower body weight growth and 2.6 times higher mortality) was observed in the high dietary vitamin supplementation treatments which was not present in the simultaneous high trace mineral and vitamin supplementation treatments (8% higher body weight increase and 2.8 times lower mortality in the high trace mineral supplementation treatments). In the high trace mineral supplemented dietary treatments was also observed improved FCR (8.5 %) and a further improvement in performance was seen in the treatments with simultaneous high essential amino acid and trace mineral supplementation levels (12.6 % higher body growth increase). Redox-sensitive gene and extracellular matrix components’ gene transcription effects and compensatory mechanisms on protein and energy metabolism, immune modulation, skin repair systems and erythropoiesis were observed by transcriptomic and histological analyses in response to the variable dietary essential nutrient levels.

Highlights

Responsible growth of the fish farming industry requires simulta neous development of sustainable technologies and knowledge that secure fish performance, health, and welfare in constantly changing and challenging conditions
Over half of all the fish that died post transfer (29 out of total 55) had increased their weight during smoltification (Fig. 1B) and most are assumed to have been feeding to some degree, justi fying our assumption that a significant proportion of the mortality can have been a result of the dietary treatments
Considering body growth rate in groups of the fish pop ulations in each treatment by size ranking, we found a positive effect of + Amino acids (AA) on body growth in the 5% largest fish

Summary

Introduction

Responsible growth of the fish farming industry requires simulta neous development of sustainable technologies and knowledge that secure fish performance, health, and welfare in constantly changing and challenging conditions. Farming mortality rates for Atlantic salmon and rainbow trout averaged 13.3 % in 2018 against 14.7 % in 2017 (Fiskeridirektoratet, 2019), and smoltification, sea water transfer, vaccination, infectious disease, treatments, stocking densities and water quality are bottlenecks contributing to stress and limiting fish growth and survival (Hjeltnes et al, 2019). Stress tolerance and reduced skin ulcer healing capacity at smolt transfer are likely to be linked to sub-optimal trace mineral and vitamin nutrition, whereas poor smoltification and transfer performance may be linked to the fish’s poor essential amino acid and trace mineral status (Salte et al, 1994; Wahli et al, 2003). Suboptimal histidine (His) levels in the diet are the identified cause behind the development of cataracts in Atlantic salmon smolt following transfer (Remø et al, 2014). For instance cataract has been related with the levels of free anserine in the fish tissues, whose biosynthesis involves either His or methionine (Met), occurring via condensation of Nπ-methyl-l-histidine with β-alanine and direct N-methylation of carnosine using S-adeno syl-l-methionine as a methyl group donor (Yamada, 2013)

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