Different Fish Meal and Fish Oil Dietary Levels in European Sea Bass: Welfare Implications After Acute Confinement Stress

Abstract

To provide practical feeding management guidelines preceding a stressful episode during farming practices, European sea bass juveniles (initial weight: 72.3 g) were fed for 60-days different fish meal (FM) and fish oil (FO) dietary levels [high (30% FM, 15% FO, FM30/FO15), intermediate (20% FM, 7% FO, FM20/FO7), and low (10% FM, 3% FO, FM10/FO3)] in triplicate conditions. Fish were then fasted for 36 h and exposed to a 2-h acute crowding (80 kg m–3 biomass). Plasma biochemistry, skin mucus parameters and gene expression of stress and immune-related genes were performed before, at 2 and 24 h after crowding. At the end of the trial, the FM10/FO3 group showed lower final body weight, weight gain, and specific growth rate compared to the other treatments. Most of the plasma parameters were mainly affected by crowding condition rather than diet; however, after stress, lactate was higher in the FM30/FO15 group compared to the other treatments. Similarly, protease, antiprotease, peroxidase and lysozyme in skin mucus were mostly affected by crowding conditions, while fish fed FM10/FO3 displayed higher skin mucosal IgM and bactericidal activity against Vibrio anguillarum and V. harveyi. Most of the stress-related genes considered (hsp70 and gr-1 in the brain; hsp70, gr-1 and gr-2 in the head kidney), showed an overall expression pattern that increased over time after stress, in addition, hsp70 in the head kidney was also up-regulated in fish fed FM30/FO15 after stress. Higher plasmatic lactate together with the up-regulation of some stress-related transcripts suggest a higher reactivity to acute crowding of the stress-response mechanism in fish fed high FM and FO dietary levels. Otherwise, the higher skin mucosal IgM and bactericidal activity observed in fish fed FM10/FO3 dietary levels seems to indicate that acute crowding was able to activate a higher pro-inflammatory response in this treatment. Overall, the results of the present study seem to indicate that 10% FM and 3% FO dietary levels might affect stress and immune responses.

Positive effects of dietary Clostridium butyricum supplementation on growth performance, antioxidant capacity, immunity and viability against hypoxic stress in largemouth bass

“…For largemouth bass, it is equally important to ensure their health and optimize growth performance. Blood biochemical indicators can provide valuable insights into the fish’s overall health status, nutritional condition, and adaptability to its environment ( 43 – 46 ). Therefore, the effect of dietary additives on blood biochemical indicators must be verified before application.…”

“…Blood biochemical indicators can provide valuable insights into the fish's overall Effect of dietary CB on antioxidant activity in the liver of largemouth bass. health status, nutritional condition, and adaptability to its environment (43)(44)(45)(46). Therefore, the effect of dietary additives on blood biochemical indicators must be verified before application.…”

Yeast-extracted nucleotides and nucleic acids as promising feed additives for European sea bass (Dicentrarchus labrax) juveniles

“…To meet the continuously rising demand, Mediterranean marine aquaculture sector urges a continuous production improvement, especially for aquafeed, which covers approximately up to 70% of the total running expenses and is mainly bound to fish meal (FM) as the major but unsustainable protein source, especially for carnivorous fish species (Guillen and Carvalho, 2016;Dawood and Koshio, 2020). So far, the main solution has been the consistent FM replacement with alternative agricultural crop-derived ingredients though with some problems related to anti-nutritional and nutrient requirements issues (Hua and Bureau, 2012;Nasopoulou and Zabetakis, 2012;Bonvini et al, 2018a;Sutili et al, 2018;Parma et al, 2019;Pelusio et al, 2022). As a further step beyond, tailored functional aquafeeds able to improve growth, feed utilization, general health and stress resistance of animals, represent a new emerging paradigm of current fish nutrition to compensate the negative effects of alternative or low FM based diets and improve cost-effectiveness (Hossain and Koshio, 2017a;Dawood et al, 2018).…”

“…European sea bass (Dicentrarchus labrax) is one of the major Mediterranean aquaculture species in the European Union and it is well known to be a model organism (Vandeputte et al, 2019). In recent years, though its carnivorous regime, sea bass diet formulation has been achieving even low FM contents with commercial potential application (Pelusio et al, 2022). For these reasons, the aim of the present study was to evaluate the effects of dietary NT and NA addition on growth and gut health of European sea bass juveniles fed different low FM level.…”

Exploring the application of Corynebacterium glutamicum single cell protein in the diet of flathead grey mullet (Mugil cephalus): effects on growth performance, digestive enzymes activity and gut microbiota

“…In addition, being a consumer of the lower trophic layers, its protein requirement is considered to be lower when compared to strict carnivorous farmed Mediterranean species. For instance, the protein content of standard aquafeed formulations for gilthead sea bream and European sea bass is normally around 45% (Busti et al, 2020a;Pelusio et al, 2022), while for flathead grey mullet can be as low as 30% (De Carvalho et al, 2010;Talukdar et al, 2020). Among the protein sources commonly used in aquafeeds, fishmeal (FM) is recognised as the most suitable in terms of nutritional value.…”