AUTHOR=Basto Ana , Calduch-Giner Josep , Oliveira Beatriz , Petit Lisa , Sá Tiago , Maia Margarida R. G. , Fonseca Susana C. , Matos Elisabete , Pérez-Sánchez Jaume , Valente Luisa M. P. 

TITLE=The Use of Defatted Tenebrio molitor Larvae Meal as a Main Protein Source Is Supported in European Sea Bass (Dicentrarchus labrax) by Data on Growth Performance, Lipid Metabolism, and Flesh Quality

JOURNAL=Frontiers in Physiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2021.659567

DOI=10.3389/fphys.2021.659567

ISSN=1664-042X

ABSTRACT=<sec><title>Objective</title><p>This study aims to determine the maximal inclusion level of defatted (<italic>d</italic>-) <italic>Tenebrio molitor</italic> larvae meal (TM) able to replace dietary fishmeal (FM) without compromising growth performance, general metabolism, and flesh quality traits in European sea bass, and to evaluate the major underlying physiological mechanisms.</p></sec><sec><title>Materials and Methods</title><p>Fish (55 ± 2 g) were fed with diets containing increasing levels of <italic>d</italic>TM: 0, 40, 80 and 100% (CTRL, TM40, TM80, and TM100, respectively) to replace FM. After 10 weeks of feeding, the growth performance, nutrient and energy balance, intestinal integrity, plasma metabolites and the expression of genes related to growth and nutrient metabolism, in liver and muscle were determined. The fatty acids (FA) profile, textural properties and color were also evaluated in muscle.</p></sec><sec><title>Results</title><p>Protein and lipids digestibility remained unaltered up to 80% <italic>d</italic>TM inclusion. Growth performance parameters were similar among dietary treatments. The <italic>d</italic>TM inclusion increased the hepatosomatic index in fish fed TM100. Muscle eicosapentaenoic acid, docosahexaenoic acid and n-3 long-chain polyunsaturated FA levels were maintained up to 80% <italic>d</italic>TM inclusion, but total cholesterol and non-esterified FA increased with dietary <italic>d</italic>TM inclusion. In liver, the expression of elongation of very long-chain FA protein 6 (<italic>elovl6</italic>) and FA desaturase 2 (<italic>fads2</italic>) did not change in fish fed TM40 and TM80, but <italic>elovl6</italic> decreased whilst <italic>fads2</italic> increased in fish fed TM100 when compared to those fed CTRL. The expression of cholesterol 7 alpha-monooxygenase (<italic>cyp7a1</italic>) decreased with dietary <italic>d</italic>TM inclusion. In muscle, the expression of myoblast determination protein-2 (<italic>myod2</italic>) decreased in fish fed TM80 and TM100.</p></sec><sec><title>Conclusion</title><p>It is feasible to substitute dietary FM by <italic>d</italic>TM up to 80% in European sea bass without detrimental effects on nutrient digestibility, growth performance and associated genetic pathways, whilst assuring fillet nutritional value for human consumption.</p></sec>