Effects of dietary purified rapeseed protein concentrate on hepatic gene expression in juvenile turbot (Psetta maxima)

Abstract

Despite considerable progress in the production of alternative diets, small concentrations of antinutrients remain common in aquaculture nutrition, resulting in a perpetual limitation with regard to the inclusion of plant ingredients in aquafeeds. These compounds are known to impair the general performance of fish when fed for a prolonged period of time, potentially affecting the animal's susceptibility to stress, too. Therefore, a 12-week feeding trial was conducted to examine the chronic effects of purified rapeseed protein concentrate (RPC), containing low concentrations of glucosinolates and phytic acid, on the relative expression of multiple target genes in the liver of juvenile turbot (Psetta maxima, L.). Our results revealed divergent patterns of gene expression, suggesting different coping strategies dependent on the grade of RPC substitution. Data implies increased metabolic rate of turbot fed a 33% RPC-substituted diet due to an upregulation of cytochrome c oxidase mRNA, accompanied by minor adjustments in metabolic pathways. While no signs of reduced welfare were found, data adumbrate a beneficial hormetic reaction. In the highest treatment level (66% RPC), diminished fish condition and reduced growth performance coincided with a downregulation of insulin-like growth factor I, further indicating a potential impaired resistance to stress. An additional downregulation of transferrin hints towards an increased liability to bacterial infections.

Sustainable fish feeds: potential of emerging protein sources in diets for juvenile turbot (Scophthalmus maximus) in RAS

“…In the present study, the more sustainable feed formulations, in which fish-derived ingredients were reduced by 20%, resulted in juvenile turbot with similar growth comparing to the control (commercial-type feed) group. This is congruent with literature where decreased growth and feed performance were observed when more than 30-35% of fishmeal was replaced by processed animal protein (Dong et al 2016), insect meal (Kroeckel et al 2012) and plant protein (Bian et al 2017;Bonaldo et al 2015;Burel et al 2000a;Fournier et al 2004;Hermann et al 2016;von Danwitz et al 2016). Nevertheless and not unexpected, compared to controls, fish that were fed the slightly leaner experimental diets were less capable of building up energy reserves as the hepatosomatic index (HSI) and the slightly lower liver glycogen show, possibly augmented by a slightly lower apparent digestibility of dietary protein (2%) and energy (3%) of the control diet compared to the experimental diets.…”

Effects of highly purified rapeseed protein isolate as fishmeal alternative on nutrient digestibility and growth performance in diets fed to rainbow trout ( Oncorhynchus mykiss )

“…It appears likely that reduced DFI caused impaired growth performance when fishmeal was replaced completely by rapeseed protein isolate in this study. The latter assumption is in line with results of various studies observing reduced feed intake due to increasing dietary content of rapeseed protein concentrate or isolate in different species of fish (Hermann et al, 2016;Kissil et al, 2000;Nagel et al, ,2012Nagel et al, , , 2017Slawski, 2012). ANFs such as glucosinolates and phytic acid were made responsible for reduced feed palatability when rapeseed protein products were used as fish feed ingredients (Francis et al, 2001).…”

Dietary β-glucan (MacroGard®) enhances survival of first feeding turbot (Scophthalmus maximus) larvae by altering immunity, metabolism and microbiota

“…Primers specific for immune, nutritional and house keeping genes were either taken from [40], [41] or designed with Primer 3 using sequences from Genbank (Table 1). Sequences similar to sod, gpx, and chym were identified via BLAST search.…”