Application of Fermented Brewer’s Spent Grain Extract in Plant-Based Diets Improves Pre- and Post-mortem Oxidative Status of European Seabass (Dicentrarchus labrax)

Abstract

In a previous study, it was shown that dietary supplementation with a carbohydrases and antioxidant-enriched extract (BSG-extract) produced by solid-state fermentation of brewer’s spent grain (BSG) improved nutrients digestibility, feed, and protein utilization of European seabass juveniles. This work aims to investigate the effect of this BSG-extract on liver and intestine oxidative status and muscle lipid peroxidation (LPO) of European seabass. A plant-based diet (55.4% plant feedstuffs; PF) was used as a control. Four test diets were formulated by supplementing the control diet with the BSG-extract (0.4 or 0.8% diet), added directly to the diet (BSG4 and BSG8 diets), or used to pre-treat the PF mixture of the control diet (PreBSG4 and PreBSG8 diets). European seabass juveniles (IBW 22 ± 1 g) were fed the experimental diets for 66 days until apparent satiety. In fish fed BSG-extract diets, compared to the control diet, intestinal LPO was reduced up to 29-40% ( p < 0.05 ); GPX, GR, and G6PD activities were increased compared to the control ( p < 0.05 ). In the liver, LPO was similar among diets, but except for catalase and G6PD, fish fed BSG-extract diets had higher antioxidant enzyme activities than the control ( p < 0.05 ). Except for the liver SOD activity, hepatic and intestinal antioxidant capacity was not affected by the dietary BSG-extract incorporation mode ( p > 0.05 ). After 72 h of storage at 4°C, muscle LPO was higher than at time 0 h. Compared to the control, BSG-extract reduced muscle LPO levels up to 30% at time 0 h in fish fed diets BSG4, BSG8, and PreBSG8 ( p < 0.008 ). Results indicate that dietary supplementation with BSG-extract increased the antioxidant level of diets, improved the intestine antioxidant capacity, and decreased LPO in European seabass juveniles’ muscle.

Solid-State Fermentation as Green Technology to Improve the Use of Plant Feedstuffs as Ingredients in Diets for European Sea Bass (Dicentrarchus labrax) Juveniles

“…Despite the increased apparent digestibility coefficient of protein observed with the 20 SSF diet, lipase and total alkaline protease activity decreased with the SSFed PF mixture, regardless of the inclusion level. Similarly, the dietary inclusion of 5% SSFed Ulva rigida in European sea bass did not affect amylase activity but decreased lipase and protease activities [78]. These results may be attributed to the digestion of PF protein and complex polysaccharides, favoring the access of endogenous enzymes to the substrate.…”

“…However, plasma glucose levels decreased when rainbow trout were fed diets containing 30% SSFed soybean and corn gluten meal with Bacillus subtilis U304. In European sea bass fed a plant-based diet supplemented with an extract obtained from the SSF of a brewer's spent grain with A. ibericus, the cholesterol, triglycerides, and total protein levels were affected [78]. In large yellow Croaker juveniles (Larimichthys crocea), xylanase supplementation did not affect serum glucose, total protein, and cholesterol levels, while triglycerides increased [84].…”