Search

[Background]: In order to ensure sustainability of aquaculture production of carnivourous fish species such as the gilthead seabream (Sparus aurata, L.), the impact of the inclusion of alternative protein sources to fishmeal, including plants, has been assessed. With the aim of evaluating long-term effects of vegetable diets on growth and intestinal status of the on-growing gilthead seabream (initial weight = 129 g), three experimental diets were tested: a strict plant protein-based diet (VM), a fishmeal based diet (FM) and a plant protein-based diet with 15% of marine ingredients (squid and krill meal) alternative to fishmeal (VM+). Intestines were sampled after 154 days. Besides studying growth parameters and survival, the gene expression related to inflammatory response, immune system, epithelia integrity and digestive process was analysed in the foregut and hindgut sections, as well as different histological parameters in the foregut., [Results]: There were no differences in growth performance (p = 0.2703) and feed utilization (p = 0.1536), although a greater fish mortality was recorded in the VM group (p = 0.0141). In addition, this group reported a lower expression in genes related to pro-inflammatory response, as Interleukine-1β (il1β, p = 0.0415), Interleukine-6 (il6, p = 0.0347) and cyclooxigenase-2 (cox2, p = 0.0014), immune-related genes as immunoglobulin M (igm, p = 0.0002) or bacterial defence genes as alkaline phosphatase (alp, p = 0.0069). In contrast, the VM+ group yielded similar survival rate to FM (p = 0.0141) and the gene expression patterns indicated a greater induction of the inflammatory and immune markers (il1β, cox2 and igm). However, major histological changes in gut were not detected., [Conclusions]: Using plants as the unique source of protein on a long term basis, replacing fishmeal in aqua feeds for gilthead seabream, may have been the reason of a decrease in the level of different pro-inflammatory mediators (il1 β, il6 and cox2) and immune-related molecules (igm and alp), which reflects a possible lack of local immune response at the intestinal mucosa, explaining the higher mortality observed. Krill and squid meal inclusion in vegetable diets, even at low concentrations, provided an improvement in nutrition and survival parameters compared to strictly plant protein based diets as VM, maybe explained by the maintenance of an effective immune response throughout the assay., The research has been partially funded by Vicerrectorat d’Investigació, Innovació i Transferència of the Universitat Politècnica de València, which belongs to the project Aquaculture feed without fishmeal (SP20120603)

In this study, HPTLC was used to make a quantitative analysis of the total lipid content (TL dry weight) and their classes in 39 samples, including molluscs, crustaceans, fish and meals in an attempt to identify those most suitable for formulating diets for cephalopods by reference to an index of nutritional quality (OILC: Oser's index modified for lipid classes). All the crustaceans analysed (< 10% TL), fish from artisanal fisheries such as Boops boops, Gadus poutassou, Mugil sp. and Gadus minutus (< 10% TL) and the plant meals (TL < 5%) would cause fewer digestive problems than the fish that were a by-catch from fish farms (B. boops or Sparus aurata), pelagic species (Sardina pilchardus or Trachurus trachurus) or krill meal, which are characterised by their high lipid content (20-60% TL). These latter feeds were associated with neutral lipids, mainly triglycerides during the summer. Mytilus galloprovincialis, Carcinus maenas, G. poutassou, Mugil sp., S. pilchardus and G. minutus had a more appropriate lipid content and profile during the winter, when they showed a higher OILC due to the greater variety of polar lipid classes they contained. Phospholipids like PS, PI and PE seem to be limiting nutrients in cephalopods because of their high content (78-542, 41-309 and 152-2,114 mg/100 g, respectively) compared with the rest of the samples. None of the meals analysed showed a good nutritional balance per se and should only be used in conjunction with other foods., Project financed by the National Marine Culture Plans of JACUMAR. We thank the personnel of IRTA, ICCM, IFAPA and IEO for their help in the analytical techniques used.

The original version of this article unfortunately contained an error in the affiliation section.

Looking for good sperm diluting media, physio-chemical parameters and ionic composition of the eel seminal plasma were studied in relation with sperm motility.