Replacement of fish meal by Antarctic krill meal in diets for European sea bass Dicentrarchus labrax: Growth performance, feed utilization and liver lipid metabolism

Silvia Torrecillas,Daniel Montero,Marta Carvalho,Tibiabin Benitez-Santana,Marisol Izquierdo

doi:10.1016/j.aquaculture.2021.737166

Silvia Torrecillas, Daniel Montero + Show 3 more

Open Access

https://doi.org/10.1016/j.aquaculture.2021.737166

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Journal: Aquaculture	Publication Date: Jul 10, 2021
Citations: 17	License type: cc-by

Affiliation: University of Las Palmas de Gran Canaria

Abstract

A sustainable growth of the aquaculture sector implies the use of sustainable novel raw materials as replacers of the traditional fishmeal (FM) and fish oil (FO) ingredients. This fact has led to the development of sustainable and functional diets as part of a management strategy to reduce the effects on fish growth performance and health derived from low FM/FO dietary contents. In this sense, Antarctic krill (Euphausia superba) is considered a potential candidate in dietary inclusions to potentiate fish growth and health status. In this study, European sea bass (Dicentrarchus labrax) were fed a practical diet with either a 15% fishmeal content (KM0; control diet) or the same diet substituted by 30% (KM5; 50 g KM/kg diet) or 50% (KM7.5; 75 g KM/kg diet) Antarctic krill meal (KM) for 12 weeks in triplicates. At the end of the feeding trial, growth performance, liver morphology, liver proximate composition, lipid classes and fatty acid profiles, as well as the expression of hepatic genes related with lipid metabolism were evaluated. Fish fed KM-based diets presented higher (p < 0.05) final weight, protein and lipid efficiency ratios, specific growth rate (SGR) and improved feed conversion ratio (FCR), irrespective of the KM dietary level. Whole body and muscle proximate composition and fatty acid profiles were similar among dietary groups. Livers of European sea bass fed the experimental diets presented similar (p > 0.05) biochemical composition and fatty acid profile. However, smaller hepatocellular area and lower grade of cytoplasm vacuolization as well as a better alignment around sinusoidal spaces were found. The analyses of liver lipid classes revealed a positive correlation between the level of dietary KM and the pigmented material such as astaxanthin and free fatty acid content, as well as a negative correlation with the cholesterol levels. The expression of hepatic genes studied demonstrated a downregulation of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (hmgr) and delta-6-desaturase (fads2) expression levels in fish fed KM-based diets. Besides, gene expression levels of fatty acid binding protein 7 (fabp7) and lipoprotein lipase (lpl) were significantly correlated with KM dietary levels. Altogether, these results profile KM as a potential promoter of growth and liver health in European sea bass fed low fish meal and oil diets.

Highlights

Aquaculture products represent the 60% of total fish consumption and its production is expected to continue rising (FAO, 2020)
feed conversion ratio (FCR) was improved from 60 days of feeding onwards when diets were supplemented with krill meal (KM) (Fig. 1)
The results of the present study showed that dietary FM can be partially replaced by KM in European sea bass diets, and that KM at 5% and 7.5% promotes European sea bass juvenile’s growth perfor mance, feed and nutrient utilization

Summary

Introduction

Aquaculture products represent the 60% of total fish consumption and its production is expected to continue rising (FAO, 2020). FM can be partially replaced in the diets of many fish species, but in most cases, high or complete replacements by terrestrial ingredients have detri mental effects on fish performance and health (Hernandez et al, 2007; Xu et al, 2012; Conde-Sieira et al, 2018) This effect uses to be asso ciated to imbalanced amino acid and micronutrients profiles, to the presence of anti-nutritional factors (Ng et al, 2019; Xu et al, 2017) or to a reduction in feed intake because of a decreased diet acceptability as the level of alternative vegetal protein sources increases (Chatzifotis et al, 2008; Kissil et al, 2000; Kubitza and Lovshin, 1997). High FM replacements by terrestrial meals may results in a disruption of gut homeostasis by increasing oxidative stress (Guerreiro et al, 2015), submucosa cellular gut associated lymphoid tissue (GALT) response (Torrecillas et al, 2017b; Azeredo et al, 2017), mucus production (Torrecillas et al, 2017b) and autochthonous gut microbiota (Torrecillas et al, 2017b)

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