A plant-based diet supplemented with Hermetia illucens alone or in combination with poultry by-product meal: one step closer to sustainable aquafeeds for European seabass.

BACKGROUND: Increasing demand for high-value fish species and pressure on forage fish is challenging aquaculture to ensure sustainable growth by replacing protein sources in aquafeeds with plant and terrestrial animal proteins, without compromising the economic value and quality of the final fish product. In the present study, the effects of a plant protein-based diet (CV), two plant-based diets in which graded amounts of plan protein mixtures were replaced with Hermetia illucens meal alone (VH10) or in combination with poultry by-product meal (PBM) (VH10P30), a fishmeal (FM) diet (CF) and an FM diet supplemented with H. illucens (FH10) on growth performance, gut health and homeostasis of farmed subadult European seabass were tested and compared. RESULTS: Fish fed the VH10 and VH10P30 diets showed the highest specific growth rates and lowest feed conversion ratios among the tested groups. Expectedly, the best preservation of PI morphology was observed in fish fed the CF or FH10 diets, while fish fed the CV diet exhibited significant degenerative changes in the proximal and distal intestines. However, PBM supplementation mitigated these effects and significantly improved all gut morphometric parameters in the VH10P30 group. Partial substitution of the plant mixture with insect meal alone or PBM also induced most BBM genes and activated BBM enzymes, suggesting a beneficial effect on intestinal digestive/absorption functions. Regarding intestinal microbiota, fish fed diets containing H. illucens meal (FH10, VH10, VH10P30) had the highest richness of bacterial communities and abundance of beneficial genera such as Lactobacillus and Bacillus. On the other hand, fish fed CV had the highest microbial diversity but lost a significant component of fish intestinal microbiota, the phylum Bacteroidetes. Finally, skin pigmentation most similar to that of farmed or even wild seabass was also observed in the fish groups fed CF, FH10 or VH10P30. CONCLUSION: Plant-based diets supplemented with PBM and H. illucens pupae meal have great potential as alternative diets for European seabass, without affecting growth performance, gut homeostasis, or overall fitness. This also highlights the importance of animal proteins in diets of European seabass, as the addition of a small amount of these alternative animal protein sources significantly improved all measured parameters.

The Content of Biogenic Amines in Croatian Wines of Different Geographical Origins.

Samples of white and red wines produced in two different wine-growing regions, coastal (Dalmatia) and continental (Hrvatsko zagorje) of Croatia, were analysed for biogenic amines content. Biogenic amines content was determined, and its concentration levels were associated with the geographical origin of the wine. Due to its high sensitivity, HPLC method with ultraviolet detector was used, including the derivatisation step with dansyl chloride. The method was applied to detect and quantify 11 biogenic amines in 48 red and white wines. It was found that both Dalmatian red and white wines are characterised by tryptamine (0.23⁻1.22 mg L-1), putrescine (0.41⁻7.5 mg L-1) and ethanolamine (2.87⁻24.32 mg L-1). White wines from the Hrvatsko zagorje region are characterised by content of isopentylamine (0.31⁻1.47 mg L-1), putrescine (0.27⁻1.49 mg L-1) and ethanolamine (3.80⁻17.96 mg L-1). In contrast to white wines from the Hrvatsko zagorje region, in the red wines, all biogenic amines except ethylamine, were found and equally presented.