Aquafeed Ingredients Research Articles

Effect of different processing techniques on nutrient and anti-nutrient compositions of plant feedstuffs for their probable use as aqua-feed ingredients

Effect of different processing techniques on nutrient and anti-nutrient compositions of plant feedstuffs for their probable use as aqua-feed ingredients

Plant-Based Diets Induce Transcriptomic Changes in Muscle of Zebrafish and Atlantic Salmon.

With the expansion of the aquaculture industry in the last two decades, there has been a large increase in the use of plant ingredients in aquafeeds, which has created new challenges in fish growth, health and welfare. Fish muscle growth is an important trait that is strongly affected by diet, but our knowledge on the effect of plant protein-based diets on global gene expression in muscle is still scant. The present study evaluated nutrigenomic effects of the inclusion of proteins from pea, soy and wheat into aquafeeds, compared to a control diet with fishmeal as the main protein source using the zebrafish model by RNA-seq; these results were extended to an important aquaculture species by analyzing selected differentially expressed genes identified in the zebrafish model on on-growing Atlantic salmon fed with equivalent plant protein-based diets. Expression of selected Atlantic salmon paralogues of the zebrafish homologs was analyzed using paralogue-specific qPCR assays. Global gene expression changes in muscle of zebrafish fed with plant-based diets were moderate, with the highest changes observed in the soy diet-fed fish, and no change for the pea diet-fed fish compared to the control diet. Among the differentially expressed genes were mylpfb, hsp90aa1.1, col2a1a, and odc1, which are important in regulating muscle growth, maintaining muscle structure and function, and muscle tissue homeostasis. Furthermore, those genes and their paralogues were differentially expressed in Atlantic salmon fed with the equivalent percentage of soy or wheat protein containing diets. Some of these genes were similarly regulated in both species while others showed species-specific regulation. The present study expands our understanding on the molecular effects of plant ingredients in fish muscle. Ultimately, the knowledge gained would be of importance for the improved formulation of sustainable plant-based diets for the aquaculture industry.

Do background levels of the pesticide pirimiphosmethyl in plant-based aquafeeds affect food safety of farmed Atlantic salmon?

ABSTRACT The substitution of fish oil and fishmeal with plant-based ingredients in commercial aquafeeds for Atlantic salmon, may introduce novel contaminants that have not previously been associated with farmed fish. The organophosphate pesticide pirimiphos-methyl (PM) is one of the novel contaminants that is most prevalent in commercial salmon feed. In this study, the feed-to-fillet transfer of dietary PM and its main metabolites was investigated in Atlantic salmon fillet. Based on the experimental determined PM and metabolite uptake, metabolisation, and elimination kinetics, a physiologically based toxicokinetic (PBTK) compartmental model was developed. Fish fed PM had a relatively low (~4%) PM retention and two main metabolites (2-DAMP and Desethyl-PM) were identified in liver, muscle, kidney and bile. The absence of more metabolised forms of 2-DAMP and Desethyl-PM in Atlantic salmon indicates different metabolism in cold-water fish compared to previous studies on ruminants. The model was used to simulate the long term (>1.5 years) feed-to-fillet transfer of PM + metabolite in Atlantic salmon under realistic farming conditions including seasonal fluctuations in feed intake, growth, and fat deposition in muscle tissue. The model predictions show that with the constant presence of the highest observed PM concentration in commercial salmon feed, fillet PM+ metabolite levels were approximately 5 nmol kg−1, with highest levels for the metabolite 2-DAMP. No EU maximum residue levels (MRL) for PM and its main metabolites exist in seafood to date, but the predicted levels were lower than the MRL for PM in swine of 32.7 nmol kg−1.

Digestibility and gastrointestinal transit of Ulva fasciata seaweed meal in tilapia (Oreochromis niloticus) juveniles: basis for the inclusion of a sustainable ingredient in aquafeeds

The seaweed Ulva fasciata has many features favorable to integrated multi-trophic aquaculture (IMTA). It is efficient at biofiltering, shows high biomass production, and is rich in many nutrients useful in aquatic animal diets. We evaluated the digestibility of the seaweed meal of U. fasciata produced in IMTA and its effects on gastrointestinal transit time in tilapia (Oreochromis niloticus) juveniles. Juveniles (6.30 ± 1.80 g initial weight, and 5.5 ± 0.61 cm initial length) were cultivated in six tanks (50 individuals per tank) in a closed recirculating aquaculture system. The digestibility of Ulva meal was 57.92 ± 5.21% for dry material, 78.59 ± 1.91% for protein, and 69.87 ± 3.72% for energy. The inclusion of 10% seaweed meal did not alter the gastrointestinal transit time in tilapia juveniles as compared to controls. The earliest colored feces were observed four hours after first feeding in both treatments (feed diets with [10%] and without seaweed); all fecal material was colored after ten hours. The digestibility of seaweed meal was satisfactory for dry material, protein, and gross energy, and the inclusion of 10% of that meal did not change gastrointestinal transit time - indicating that the inclusion of 10% seaweed meal in tilapia diet is safe and without any nutritional use losses.

Effects of selenium-enriched prebiotic on the growth performance, innate immune response, oxidative enzyme activity and microbiome of rainbow trout (Oncorhynchus mykiss)

Using prebiotics as functional ingredients in aquafeed is an emerging approach to prevent disease and improve fish production. This study explored the effect of supplementing aquafeed with selenium-enriched prebiotic on the growth performance, plasma lysozyme activity, and oxidative enzymes activities of various tissues of the rainbow trout, Oncorhynchus mykiss. The fish scale and intestinal microbiomes were also characterized. A genetically- modified, whole-cell inactivated Schizosaccharomyces pombe that produces a novel form of selenium called selenoneine was used as a prebiotic supplement in this study. Selenoneine is a novel selenium-containing molecule with an antioxidant activity, suggesting it has potential to improve the production of fish when used as a functional ingredient in aquafeeds. To investigate if this selenium-enriched S. pombe can strengthen the production metrics, modulate the surface and internal microbiome, and improve the health status of fish, an 8-week fish feeding trial was conducted. A commercial feed was supplemented with no addition (control), 5 g Kg−1 (0.5%), or 10 g Kg−1 (1.0%) of selenium-enriched S. pombe. Fish were harvested at the middle (week 4) and end of the trial (week 8). There were no significant differences (p > 0.05) in food conversion ratio, condition factor, or survival of fish during the trial. The microbiome also remained stable during the experiment. No effect (p > 0.05) was observed in the growth performance of the fish at week 4; however, at week 8 fish that were fed 0.5% yeast had a significantly higher weight gain (p < 0.05), hepatosomatic index, and viscerosomatic index than the fish fed control and 1.0% diets. At week 4, the concentration of plasma lysozyme in fish fed 0.5% yeast was significantly higher (p < 0.05) than the control fish and fish fed the 1.0% diet. No significant differences (p > 0.05) were observed in glutathione peroxidase activity in the liver, kidney, or plasma of fish fed experimental diets at the two different sampling times. However, the superoxide dismutase activity of plasma was significantly higher with the 0.5% diet than the control and 1.0% fed fish at week 4. At week 8, both the 0.5% and 1.0% diets led to significant increases (p < 0.05) in superoxide dismutase activity in the plasma of fish when compared to the control diet. This study demonstrates that supplementation of aquafeed with selenoneine-producing S. pombe can improve the growth, immune response, and oxidative status of fish. Thus, this ingredient holds a promising potential to enhance sustainability within the aquaculture industry.

Yeast as major protein‐rich ingredient in aquafeeds: a review of the implications for aquaculture production

AbstractSustainability concerns associated with protein sources and currently used fishmeal and plant‐based meal have necessitated the quests for novel sustainable ingredients for use in aquafeeds. Yeasts have been proposed as sustainable ingredients particularly because of their potential to valorise non‐food lignocellulosic biomass into valuable protein resources. Prior to now, extensive studies exist on the role of yeast cell wall components in modulating health responses of fish. However, research on its use as a major protein source in fish diets is still in its infancy. The current review collates, synthesises and discusses the prospects of five major yeast species as future protein ingredients with respect to their nutritional adequacy in fish. Nutritional quality of Saccharomyces cerevisiae, Cyberlindnera jadinii, Kluyveromyces marxianus, Blastobotrys adeninivorans and Wickerhamomyces anomalus and their use as replacement for fishmeal and soy protein in the diets of Atlantic salmon and rainbow trout are discussed based on three protein quality indices: chemical score, essential amino acid index and ideal protein concept based on the first limiting amino acids, methionine. The crude protein contents of yeast (40–55%) are lower than that of fishmeal, but comparable with soya bean meal. Compared to fishmeal, the different yeast species have favourable amino acid profiles, except for methionine, lysine, arginine and phenylalanine which are the frequently limiting essential amino acids in Atlantic salmon and rainbow trout. This review also presents future area of research and emphasise the need for large‐scale production of yeast at competitive price to constitute a feasible replacement for fishmeal and soy protein in aquaculture.

Effect of low levels of fumonisin contamination on gilthead seabream (Sparus aurata)

AbstractUse of plant‐based ingredients in aquafeeds, especially for carnivorous species, is likely to increase in view of concerns regaridng the sustainability, price, and availability of fishmeal. As mycotoxins are a common problem associated with the use of plant ingredients, this study was undertaken to evaluate the effect of two levels of fumonisins (168 μg/kg feed and 333 μg/kg) and compared with 0μg/kg (the Control diet) for total growth, whole‐body nutrient retention, liver enzyme activity, and several plasma humoral parameters in juvenile gilthead seabream, Sparus aurata. Results suggest that diets contaminated with fumonisins can be detrimental to the growth performance of seabream. Fumonisin levels as low as 168 μg/kg feed had a significant impact on final body weight, feed conversion ratio, and protein efficiency ratio. Fumonisins also reduced fat and energy retention and disrupted the respiratory burst in circulating leukocytes. Fumonisin levels at 333 μg/kg feed increased these detrimental effects, clearly demonstrating a dose–response relationship. These results highlight the possible need to re‐evaluate the European Commission guidance value for fumonisins (FB1 + FB2) in complementary and complete feedstuffs for fish of 10,000 μg/kg, which might be too high for certain species, such as seabream.

Genistein Induces Adipogenic and Autophagic Effects in Rainbow Trout (Oncorhynchus mykiss) Adipose Tissue: In Vitro and In Vivo Models.

Soybeans are one of the most used alternative dietary ingredients in aquafeeds. However, they contain phytoestrogens like genistein (GE), which can have an impact on fish metabolism and health. This study aimed to investigate the in vitro and in vivo effects of GE on lipid metabolism, apoptosis, and autophagy in rainbow trout (Oncorhynchus mykiss). Primary cultured preadipocytes were incubated with GE at different concentrations, 10 or 100 μM, and 1 μM 17β-estradiol (E2). Furthermore, juveniles received an intraperitoneal injection of GE at 5 or 50 µg/g body weight, or E2 at 5 µg/g. In vitro, GE 100 μM increased lipid accumulation and reduced cell viability, apparently involving an autophagic process, indicated by the higher LC3-II protein levels, and higher lc3b and cathepsin d transcript levels achieved after GE 10 μM. In vivo, GE 50 µg/g upregulated the gene expression of fatty acid synthase (fas) and glyceraldehyde-3-phosphate dehydrogenase in adipose tissue, suggesting enhanced lipogenesis, whereas it increased hormone-sensitive lipase in liver, indicating a lipolytic response. Besides, autophagy-related genes increased in the tissues analyzed mainly after GE 50 µg/g treatment. Overall, these findings suggest that an elevated GE administration could lead to impaired adipocyte viability and lipid metabolism dysregulation in rainbow trout.

The Application of Single-Cell Ingredients in Aquaculture Feeds—A Review

Single-cell ingredients (SCI) are a relatively broad class of materials that encompasses bacterial, fungal (yeast), microalgal-derived products or the combination of all three microbial groups into microbial bioflocs and aggregates. In this review we focus on those dried and processed single-cell organisms used as potential ingredients for aqua-feeds where the microorganisms are considered non-viable and are used primarily to provide protein, lipids or specific nutritional components. Among the SCI, there is a generalised dichotomy in terms of their use as either single-cell protein (SCP) resources or single-cell oil (SCO) resources, with SCO products being those oleaginous products containing 200 g/kg or more of lipids, whereas those products considered as SCP resources tend to contain more than 300 g/kg of protein (on a dry basis). Both SCP and SCO are now widely being used as protein/amino acid sources, omega-3 sources and sources of bioactive molecules in the diets of several species, with the current range of both these ingredient groups being considerable and growing. However, the different array of products becoming available in the market, how they are produced and processed has also resulted in different nutritional qualities in those products. In assessing this variation among the products and the application of the various types of SCI, we have taken the approach of evaluating their use against a set of standardised evaluation criteria based around key nutritional response parameters and how these criteria have been applied against salmonids, shrimp, tilapia and marine fish species.

Dietary administration effects of exopolysaccharide from potential probiotic strains on immune and antioxidant status and nutritional value of European sea bass (Dicentrarchus labrax L.)

The use of biological immunostimulants is considered a valuable practice to improve culture conditions in aquaculture sector that may help to increase production and maintain healthy environment. We undertook this study in order to evaluate the potential effect of the administration of two exopolysaccharides (EPS) “EPLB” and “EPB” derived from potential probiotic strains on immune and antioxidant status of European sea bass (Dicentrarchus labrax L.) larvae. In order to find out if the EPSs have an effect on the biochemical composition during the trial period, the nutritional value has been evaluated. The results revealed that expression levels of immune-relevant genes (infg, Il1b, Il8, Il6 and tcr-β) in the gut and head kidney and the scavenging enzymes (cat, sod, gr) genes in the liver were modulated. In fact, the dietary supplementation with the tested EPSs, significantly enhances the expression of immune-associated genes in the head-kidney, particularly infg and tcrβ, as well as catalase gene in liver. During the period of study, EPSs administration did not affect the fatty acid profiles of larvae, which is balanced. This is confirmed by the Docosahexaenoic acid / Eicosapentaenoic acid ratio and demonstrates that EPLB and EPB can be administrated without any negative effect on biochemical composition of European sea bass. The present findings provided evidence that the tested EPSs with antibacterial and antioxidant activities can enhance immune response without negative effect on the biochemical composition. The used EPSs can be considered as a good source of natural functional aquafeed ingredients for European sea bass.

Diphenyl diselenide dietary supplementation protects against fumonisin B1-induced oxidative stress in brains of the silver catfish Rhamdia quelen

The trend toward using plant-based ingredients in aquafeeds has raised important concerns for aquaculture owing to the negative impacts of mycotoxins on fish health; with emphasis for contamination by fumonisin B1 (FB1). The brain is an important target of FB1; however, study of the pathways linked to brain damage is limited to an analysis of histopathological alterations. Reports have demonstrated the protective effects of dietary supplementation with diphenyl diselenide (Ph2Se2) in the brains of fish subjected to several environmental insults; nevertheless, its neuroprotective effects in fish fed with diets contaminated with FB1 remain unknown. Therefore, the aim of this study was to evaluate whether oxidative damage may be a pathway associated with FB1-induced neurotoxicity, as well as to evaluate whether dietary supplementation with Ph2Se2 prevents or reduces FB1-mediated brain oxidative damage in silver catfish. Brain reactive oxygen species (ROS), lipid peroxidation (LOOH) and protein carbonylation increased on day 30 post-feeding in animals that received FB1-contaminated diets compared to the control group, while brain antioxidant capacity against peroxyl radicals (ACAP) levels and catalase (CAT), glutathione peroxidase (GPx) and glutathione S-transferase (GST) activities were lower. Diphenyl diselenide dietary supplementation avoid increases in brain ROS levels, as well minimizing the augmentation of LOOH levels. Furthermore, Ph2Se2 prevented impairment of brain ACAP levels, as well as GPx and GST activities elicited by FB1-contaminated diets. These data suggest that dietary supplementation with 3 mg/kg Ph2Se2 prevented FB1-induced brain damage in silver catfish, and this protective effect occurred through avoided of excessive ROS production, as well as via prevention of brain lipid damage. Furthermore, Ph2Se2 exerted its neuroprotective effects via ameliorative effects on the enzymatic and non-enzymatic antioxidant defense systems, and may be an approach to prevent FB1-induced brain oxidative stress; however, is not an alternative to prevent the impairment on performance caused by FB1.

An OLED-based genosensor for the detection of Hermetia illucens in feeds

Recently, the insects meal has been released by the European Union as an ingredient in aquafeeds and only seven insect species have been allowed to be used for these preparations. To avoid misleading results, a suitable method for the detection of these insect species in food/feed, would be highly desirable. In this paper, we present an innovative, sensitive, specific and low-cost Point-of-Care apparatus, based on DNA probes for the detection of one of the most popular insects used in aquafeed preparation, Hermetia illucens (HI), commonly known as black soldier fly. The DNA probes adopted for this genosensor have been designed to enable a very specific insect recognition which were derived from DNA primers. The DNA primers were first tested with qPCR. Forty different samples (animal species and common aquafeed ingredients) have been tested to check the possible cross-reactivity, confirming the adequate primers specificity. The primers have been used in a practical application, like the detection of HI in complex matrices of practical aquafeeds. The DNA probes derived by these primers have been then applied to implement an Organic Light Emitting Diode (OLED) based genosensor. The developed genosensor has been tested with HI DNA directly extracted from the insect, without any DNA amplification; a good test sensitivity has been obtained, being 0.75 ng/μl its detection (LOD) limit. Then, the genosensor has been tested with the DNA extracted from the same aquafeeds used in the qPCR experiments. The results obtained by these two methods have then been compared giving very good consistency and both allowed to detect HI meal up to a minimum threshold of 5 g/100gr feed.

Potential of the polychaete Hediste diversicolor fed on aquaculture and biogas side streams as an aquaculture food source

AEI Aquaculture Environment Interactions Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AEI 11:551-562 (2019) - DOI: https://doi.org/10.3354/aei00331 Potential of the polychaete Hediste diversicolor fed on aquaculture and biogas side streams as an aquaculture food source Haiqing Wang1,2,*, Andreas Hagemann2, Kjell Inge Reitan1, Jørgen Ejlertsson3, Håvard Wollan4, Aleksander Handå2, Arne M. Malzahn2 1Norwegian University of Science and Technology, Department of Biology, 7491 Trondheim, Norway 2SINTEF Ocean, 7465 Trondheim, Norway 3Scandinavian Biogas, 58273 Linköping, Sweden 4Biokraft AS, 7042 Trondheim, Norway *Corresponding author: haiqing.wang@ntnu.no ABSTRACT: We evaluated the potential of the marine bristleworm Hediste diversicolor (Polychaeta) to recycle side streams from aquaculture and biogas production. Polychaetes were fed along a gradient from pure aquaculture sludge (SS) to pure solid biogas digestate (SBD) in 33% steps, with a positive control reared on fish feed (FF). Worms fed with FF showed the highest specific growth rate; there were no significant differences in growth rates among worms fed pure SS, pure SBD or their mixtures. While the diets differed significantly in protein concentrations, the worms showed comparable protein concentrations at the end of the 30 d rearing period (42-47% of dry weight). Lipid content in the worms was positively correlated with that in their diets. The worms on mixtures of SS and SBD with different ratios showed similar amino acid profiles. Fatty acid (FA) composition in the polychaetes reflected diet, where increased fractions of SBD resulted in an increase in long-chain polyunsaturated FAs, such as arachidonic (C20:4 n-6) and eicosapentaenoic (C20:5 n-3) acids, whereas increased ratios of SS increased docosapentaenoic (C22:5 n-3) and docosahexaenoic (C22:6 n-3) acids. These results suggest that polychaetes can recycle organic nutrients from aquaculture and biogas side streams into high-quality proteins and lipids, and can potentially serve as ingredients for aquafeeds. KEY WORDS: Recycling · Salmon culture · Aquaculture waste · Solid biogas digestate · Aquafeed Full text in pdf format Supplementary material PreviousNextCite this article as: Wang H, Hagemann A, Reitan KI, Ejlertsson J, Wollan H, Handå A, Malzahn AM (2019) Potential of the polychaete Hediste diversicolor fed on aquaculture and biogas side streams as an aquaculture food source. Aquacult Environ Interact 11:551-562. https://doi.org/10.3354/aei00331 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AEI Vol. 11. Online publication date: November 14, 2019 Print ISSN: 1869-215X; Online ISSN: 1869-7534 Copyright © 2019 Inter-Research.

Rainbow trout prefer diets rich in omega-3 long chain polyunsaturated fatty acids DHA and EPA

The control of feed intake in fish in aquaculture requires the development of new techniques to improve diet composition, feed conversion efficiency and growth. The aim must be sustainability and an effective use of resources. The effect of replacing traditional aqua-feed ingredients (fishmeal and fish oil) by a 100% plant-based diet is known to drastically decrease fish performance (survival and growth). The present study examined the feed preference of rainbow trout Oncorhynchus mykiss for three diets containing distinct levels of omega-3 long chain polyunsaturated fatty acids (ω-3 LCPUFA): eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (0% for low, 5% for medium and 20% for high, total fatty acid content). Feed preference values for each group (low v. medium ω-3 diets, medium v. high ω-3 diets and low v. high ω-3 diets) were observed using two self-feeders positioned at opposite sides of the tank. The hypothesis was that the decrease of fish growth and survival rate of fish fed with 100% plant-based diet could be explained by the absence of ω-3 LCPUFA relating to decrease of food intake. This could explain the tasting role of ω-3 LCPUFA in the feeding behavior of rainbow trout (which reflects the motivation to consume feed). The results showed that rainbow trout could discriminate between the diets containing different level of ω-3 LCPUFA even if unable to differentiate between level of 5% (no preference observed in low v. medium ω-3 diets). Overall they had a preference for diet high in ω-3 LCPUFA: 59.5% preference for high ω-3 diet in high v. low ω-3 diets, and 75.6% preference for high ω-3 diet in medium v. high ω-3 diets respectively. This preference was repeated after 21 days and for a further 21 days when the feeds were exchanged between the two self- feeders in each tank: 63.3% preference for high ω-3 diet in high v. low ω-3 diets, and 69,5% preference for high ω-3 diet in medium v. high ω-3 diets respectively. The tests also indicated a difference in the extent of food waste of each of the three diets revealed by uneaten pellets after feed demands. During two periods of test, high ω-3 diet was the most appreciated, the least wasted and the most eaten (all choice groups) whereas the most uneaten feed remained the least appreciated diet in three choices diets (low ω-3 diet in low v. medium ω-3 diets, medium in medium v. high ω-3 diets and low in low v. high ω-3). In conclusion, this study highlighted the influence of ω-3 LCPUFA in the feeding behavior of juvenile rainbow trout, levels of ω-3 LCPUFA drove dietary choices in the fish.

The importance of fisheries and aquaculture production for nutrition and food security.

Aquatic food has a significant role to play in global nutrition and food security but is often ignored in that debate. Understanding its potential role is made difficult by the fact that aquatic food covers a large number of species which come from both capture fisheries and aquaculture and the marine and freshwater environments, including finfish, crustacea, molluscs, echinoderms, aquatic plants and other aquatic animals. Further complications arise from the fact that both supply and consumption vary significantly between countries. There are several criteria which need to be considered when discussing nutrition and food security. These include: how much food is produced, whether that production is sustainable, whether the production supports livelihoods, what the nutritional content of the food is and whether that food is safe. The authors conclude that there are many benefits to aquatic food under each of these criteria but there are also some hurdles which need to be overcome. Increased production to feed a growing global population relies on the growth of aquaculture. Challenges to such growth include the supply of raw ingredients for aquafeeds, losses due to disease outbreaks, being able to ensure high standards of food safety and overcoming environmental limitations to expansion. There are also problems with welfare conditions for people working in the supply chain which need to be addressed. Given the challenges to nutrition and food security which the world is currently facing, it is essential that aquatic food is brought into the debate and the significant benefits that aquatic foods provide are acknowledged and exploited.

Diet Supplemented With Synthetic Carotenoids: Effects on Growth Performance and Biochemical and Immunological Parameters of Yellow Perch (Perca flavescens).

The current study assessed the effect of dietary canthaxanthin and lycopene supplementation at different concentrations on growth performance and antioxidant status in yellow perch (Perca flavescens). In this regard, fish with initial weight (32 ± 1.0 g) were divided into five groups in triplicate, and fed on carotenoid-free diet (control), canthaxanthin (CTX) (50 and 100 mg/kg diet), and lycopene (200 and 400 mg/kg diet) for 60 days. Growth parameters and antioxidant enzymes were evaluated after 30 and 60 days post feeding. Tissue liver and intestine from six fish per treatment was collected for antioxidant and digestive enzymes analysis. The results revealed a significant increase (P < 0.05) of lipid content in the group fed lycopene at a dietary level 400 mg/kg for 60 days, compared to the control. Moreover, dietary carotenoids exhibited no significant effect on growth performance; this was evidenced by no significant up-regulation of growth hormone (gh) and insulin-like growth factor 1b (igf-1b) genes after 30 and 60 days post feeding. Intestinal lipase and trypsin activities were significantly improved with dietary lycopene especially at a dose of (400 mg/kg diet) for 60 days. Malondialdehyde (MDA) level in liver was also significantly decreased with dietary lycopene (400 mg/kg diet) for 60 days. Hepatic superoxide dismutase (SOD), catalase (CAT), and Glutathione peroxidase (GSH-Px) activities were significantly decreased with dietary CTX, especially at dose (100 mg/kg diet) and lycopene at a concentration of 200 and 400 mg/kg diet after 60 days feeding. Additionally, the immune-related gene interleukin-1 beta (il-1b) mRNA expression level revealed up-regulation in groups fed on CTX at different concentrations for 30 days, and fish fed lycopene at a concentration level 400 mg/kg diet for 60 days. The obtained results concluded that dietary supplementation of canthaxanthin and lycopene could enhance immune response and maintain antioxidants defense of fish. Therefore, it considered as a functional aquafeed ingredient for yellow perch.

Brown seaweed (AquaArom) supplementation increases food intake and improves growth, antioxidant status and resistance to temperature stress in Atlantic salmon, Salmo salar.

Seaweeds represent a vast resource that remains underutilized as an ingredient in aquafeeds. Here we probed the effect of addition of AquaArom, a seaweed meal derived from brown seaweeds (Laminaria sp., kelp), to fish feed on growth performance, antioxidant capacity and temperature responsiveness of mitochondrial respiration. A commercial salmonid feed was mixed with 0 (control), 3, 6 and 10% seaweed and fed to Atlantic salmon (Salmo salar) smolts for 30 days. The smolts consumed more of the seaweed-supplemented food relative to the control and there were no mortalities. Compared with the control, the final fish weight, standard length, weight gain and SGR were higher in fish fed diets supplemented with the 3 and 10% seaweed, while growth performance for fish maintained on 6% seaweed remained neutral. Importantly, seaweed supplementation increased protein efficiency ratio (PER) and tended to improve food conversion ratio (FCR). Although the hepatosomatic and visceral indices did not change, whole gut and intestinal weights and lengths were higher in fish maintained on seaweed-supplemented diets suggesting increased retention time and a larger surface area for food digestion and nutrient absorption. Measurement of antioxidant status revealed that seaweed supplementation dose-dependently increased plasma total antioxidant capacity as well as the level of glutathione, and activities of catalase and superoxide dismutase in liver mitochondria. Moreover, seaweed supplementation reduced the effect of acute temperature rise on mitochondrial respiration and proton leak. Overall, these data suggest that AquaArom can be mixed with fish food up to 10% to increase food consumption and enhance growth performance, as well as to improve antioxidant capacity and alleviate adverse effects of stressors such as temperature in fish.

Effects of calcium carbonate inclusion in low fishmeal diets on growth, gastrointestinal pH, digestive enzyme activity and gut bacterial community of European sea bass (Dicentrarchus labrax L.) juveniles

Fishmeal (FM) possesses one of the highest buffering capacities in comparison to most alternative vegetable aquafeed ingredients and its decreasing content in current formulations might affect the ideal gastrointestinal environment for digestive enzyme action and gut bacterial community of carnivorous fish species. A study was undertaken, therefore, to assess growth response, gastrointestinal pH, digestive enzyme activity and gut bacterial community of European sea bass (Dicentrarchus labrax L.) juveniles fed low FM diets (10% FM) with or without a feed buffering additive, calcium carbonate (FM10 + B and FM10, respectively) in comparison to a standard FM diet (20% FM, FM20). Three isonitrogenous and isolipidic extruded diets were fed to triplicate fish groups of 80 individuals (initial weight: 23 g) to overfeeding over 64 days. No significant differences due to low FM dietary levels were observed in final body weight, specific growth rate, feed intake, feed and protein efficiency. Low FM diet did not affect gastrointestinal pH in the stomach, anterior intestine, mid-intestine and hindgut at 0, 4, 8 and 12 hours post meal (hpm) while the inclusion of calcium carbonate in low FM diet seems to slightly increase the pH in the hindgut at 12 hpm. The absence of significant differences of pepsin, chymotrypsin, amylase and lipase activity suggests a comparable digestive efficiency among treatments although trypsin activity was slightly reduced in low FM diets after 4 hpm. Decreasing FM content seems to exert an effect on the overall gut bacterial community analysed by next-generation sequencing even if no significant effects on specific bacterial component were detected. The gut bacterial community in all the treatments was particularly rich in lactic acid bacteria such as Lactobacillus spp. which may provide important beneficial functions for the host and be associated with a healthy intestinal epithelium. According to the results, increasing the feed buffering capacity does not seem to improve digestive conditions while it is feasible to include 10% FM dietary level in practical formulation for European sea bass juveniles without negatively affecting growth, feed efficiency and digestive luminal conditions.

Life cycle assessment of diets for gilthead seabream (Sparus aurata) with different protein/carbohydrate ratios and fishmeal or plant feedstuffs as main protein sources

PURPOSE: Aquaculture is the best alternative to fulfil global fish demand, however it still relies heavily on fisheries-derived products for aquafeeds production. This study assesses and compares the environmental impacts of producing four experimental diets to gilthead seabream with different dietary protein (P) to carbohydrate (CH) ratios (P50/CH10 and P40/CH20). The diets were made either with fish meal (FM) or plant feedstuffs (PF) as main protein sources and fish oil (FO) or vegetable oils (VO) as lipid sources. METHODS: The functional unit used was 1 kg of experimental diet. The studied boundaries included aquafeed ingredients production (S1), compound aquafeeds production under laboratory conditions (S2), and transportation between S1 and S2 locations. The present study applied the Recipe Endpoint method, hierarchist version (V1.13; Europe recipe H/A). Background data was collected from ecoinvent database and related literature. For each aquafeed ingredient used, it was accounted either the agriculture production or fishery activities, the processing unit, and transportation between the production and processing locations. Ingredient mixing and processing was done at the Marine Zoology Station (MZS) located at Porto, Portugal. It was also taken into account the road transportation of aquafeed ingredients between a commercial company and the MZS. RESULTS AND DISCUSSION: Regardless of dietary protein source or P/CH ratio used, all diets had the same single score index. In agreement with several studies, S1 was the system with the highest environmental impact. On the other hand, S2 was the lowest environmental contributor step to all formulated diets, except for diet P50/CH10, where the lowest environmental impact was related with the aquafeed ingredients transportation to MZS. Fisheries-derived ingredients were the biggest contributors to environmental impact. In the hypothesis of replacing FO from Portuguese fisheries by-products by FO of Peruvian anchovy fisheries or by soybean oil (SBO), the environmental impact of the diets would be decreased, being the replacement by SBO the best environmental alternative. CONCLUSIONS: There was highlighted a tendency for PF-based diets having lower environmental impact score when compared to the FM-based diets after both hypothetical replacements. Studying the replacement of by-products FO by Peruvian anchovy FO or by SBO allowed to emphasize the importance of adequate ingredients selection for reducing the environmental impact. As limitations of the current study it is important to mention: the use of pelletization as manufacturing process and the non-valorization of fish by-products as recycled aquafeed ingredients.

Modulation of Intestinal Microbiota in Solea senegalensis Fed Low Dietary Level of Ulva ohnoi

Gastrointestinal (GI) microbiota has a relevant role in animal nutrition, modulation of the immune system and protection against pathogen invasion. Interest in algae as source of nutrients and functional ingredients for aquafeeds is increasing in order to substitute conventional feedstuffs by more sustainable resources. The diet is an important factor in the modulation of the microbiota composition, and functional ingredients have been proposed to shape the microbiota and contribute benefits to the host. However, fish microbiome research is still limited compared to other hosts. Solea senegalensis is a flat fish with high potential for aquaculture in South Europe. In this study, a characterization of the microbiome of S. senegalensis (GI) tract and the effects of feeding Ulva ohnoi supplemented diet has been carried out. Differences in the composition of the microbiota of anterior and posterior sections of S. senegalensis GI tract have been observed, Pseudomonas being more abundant in the anterior sections and Mycoplasmataceae the dominant taxa in the posterior GI tract sections. In addition, modulation of the GI microbiota of juvenile Senegalese sole fed for 45 days a diet containing low percentage of U. ohnoi has been observed in the present study. Microbiota of the anterior regions of the intestinal tract was mainly modulated, with higher abundance of Vibrio spp. in the GI tract of fish fed dietary U. ohnoi.