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The growth of aquaculture demands intense consumption of formulated foods, scarce natural resources such as water and land. The increase in aquaculture production needs to be sustainable in several aspects of the activity, including the use of more sustainable farming systems that provide reduced water demand, less space dependence for increased production, and availability of complementary natural food. In this perspective, the biofloc system (BFT), presents itself as a more friendly cultivation technology as a way to mitigate some impacts of aquaculture production. Much research has been carried out, addressing different aspects important to the production of fish in BFT. In this review, we address how stocking density, carbon sources and carbon nitrogen ration (C/N) affect animal performance and the nutritional value of bioflocs; the use of microbial aggregates as "in situ" and "ex situ" food and the benefits in feed conversion, and their influence on the immune system and disease resistance. [ABSTRACT FROM AUTHOR]

Background: knowing the essential amino acid (EAA) requirement values is fundamental to formulate good quality and cost-effective fish feeds. However, such requirements have been established for few fish species. The estimation of amino acid requirements based on amino acid composition of fish is a fast and reliable alternative. Objective: to determine whole-body and muscle amino acid composition of Plata pompano (Trachinotus marginatus) and estimate its EAA requirements. Methods: EAA requirements were estimated using A/E ratios [(Individual EAA/Total EAA) * 1000]. Results: hystidine, leucine, lysine and phenylalanine were present in higher concentrations in muscle tissue in comparison with the whole-body. On the other hand, arginine, isoleucine, methionine, tryptophan and valine concentration were not different between whole-body and muscle. A/E ratios for Plata pompano determined in the present study are similar to those reported in other fish species, although valine A/E ratios were slightly smaller. Conclusion: until dose-response experiments are conducted to precisely determine EAA requirements, the estimated EAA values using whole-body EAA-as proposed in this study-could be used to formulate diets for Plata pompano. [ABSTRACT FROM AUTHOR]

Potential of the enzyme peroxidase (PO) from soybean meal to mitigate aflatoxin B1 (AFB1) in fish feed was evaluated. Reaction parameters studied in the wet stage of the feed production process were enzyme activity (0.01–0.1 U/g), temperature (20–36 °C), time (0–8 h) and humidity content (40–70%). Feed was produced in conformity with the National Research Council and spiked with AFB1 at 10 ng/g. Any residual concentration of AFB1 in the diet was extracted by the QuEChERS method and quantified by a liquid chromatograph with a fluorescence detector. AFB1 mitigation of 90% was reached when feed production conditions were 0.035 U/g, 32 °C, 6 h and 70% humidity. Therefore, application of PO to the feed industry may be considered a promising tool for mitigation of AFB1, considering its toxicity and frequent occurrence. In addition, it guarantees safe food for consumers of fish farming products, as AFB1 can bioaccumulate in the food chain. It also provides an alternative use for soybean meal that would previously be discarded. [ABSTRACT FROM AUTHOR]

The aim of this experiment was to evaluate the efficacy of benzocaine and eugenol as anesthetics for Trachinotus marginatus juveniles. Five concentrations of benzocaine (25, 50, 75, 100, and 150ppm) and eugenol (25, 37.5, 50, 62.5, and 75ppm) were tested. The trials were conducted in glass aquariums filled with 30l seawater (salinity 30‰ and temperature 19°C). The fish (51.4±13.5g) were individually exposed to different concentrations of each anesthetic (n=5 for each concentration). They were measured and weighed under anesthesia, and then returned to another aquarium without anesthetic for recovery. The results were evaluated using Analyses of Variance (One-Way - ANOVA) followed by the test of Duncan (95% confidence level) when necessary. Anesthesia time varied from approximately 11min (25ppm) to 2min (150ppm) for benzocaine, and from 10min (25ppm) to 2min (75ppm) for eugenol. Recovery time ranged from 3min (25ppm) to 14min (150ppm) for benzocaine and from 2min (25ppm) to 8min (75ppm) for eugenol. Benzocaine and eugenol, both at 50ppm, induce quick anesthesia and recovery (3mim for anesthesia and 5mim for recovery) for juvenile Trachinotus marginatus, and therefore are considered efficient anesthetics for this species. However, it is important to emphasize that the cost of benzocaine is 1/3 lower than eugenol to anesthetize juvenile pompano. [ABSTRACT FROM AUTHOR]

Simple Summary: Pumpkin by-products such as seeds, and pomace can be a source of nutrients for aquatic organisms. In a study evaluating the inclusion of Japanese pumpkin seeds and pomace in the diet of the Pacific white shrimp Penaeus vannamei, we found that the seeds had a negative effect on shrimp performance and a pro-oxidative effect on muscle, whereas pumpkin pomace improved the feed conversion ratio and antioxidant activity of feeds and muscle and resulted in shrimp becoming more orange, both when fresh and after cooking. We do not recommend the inclusion of pumpkin seeds in the diets of P. vannamei, and we suggest further studies evaluating higher levels of inclusion of pumpkin pomace. A 60-day feeding trial was conducted to evaluate the effects of including pumpkin seeds and pomace in the diets of Pacific white shrimp Penaeus vannamei, and the effects of these supplements on growth performance, body composition, and total polyphenol, flavonoid and carotenoid contents, as well as on total antioxidant activity, and body color parameters. Five diets were evaluated: pumpkin seeds (PS) at 50 and 100 g·kg−1, pumpkin pomace (PP) at 50 and 100 g·kg−1, and a control treatment. Pacific white shrimp (P. vannamei) juveniles (0.60 ± 0.01 g) were stocked in 15 tanks (310 L), containing 30 shrimps per tank, and the treatments were randomly distributed in triplicate. At the end of the experiment, shrimps were euthanized, weighed, and dissected for further analyses. The inclusion of PS in the diets impaired growth performance, reduced the total flavonoid content and had a pro-oxidative effect on muscle. The inclusion of PP in the diets did not affect growth performance, improved the feed conversion ratio, increased the total flavonoid content in the diets and hepatopancreas, and improved the antioxidant activity of the feeds and shrimp muscle. The total carotenoid content of the feeds increased with the inclusion of PS or PP in the diets; however, the total carotenoid content of shrimp increased only in those fed PP diets. Shrimp fed with PS diets showed a yellowish color and higher saturation when fresh and a reddish color and yellow hue angle after cooking. Shrimp fed PP diets turned reddish and yellowish, both when fresh and after cooking. The inclusion of PS in P. vannamei diets is not recommended; however, PP can be included at 100 g·kg−1 without affecting the growth parameters. Further studies evaluating the inclusion of higher PP levels in shrimp diets are recommended. [ABSTRACT FROM AUTHOR]

Simple Summary: Peroxidase (PO) is effective at mitigating or eliminating mycotoxins in fish feeds. However, the literature does not describe how the free radicals produced during oxidation by PO can interact with other nutrients and active compounds present in such feeds, affecting their bioavailability and modifying both the metabolism of the species and the quality of the final product. The objective of this study was to evaluate the impact of using PO as a treatment against mycotoxins on the nutritional quality of the fatty acids and polyphenols present in a fish feed. The results demonstrate that applying PO may have unwanted side effects on long-chain polyunsaturated fatty acids and the digestive bioaccessibility of polyphenols. Peroxidase (PO) has been applied in different areas of industrial biotechnology, including the control of contaminants like aflatoxin B1 in fish feeds. However, its potential negative interactions with the macro and micro components of feeds have not been evaluated. The aim of this study was to evaluate the impact of PO's addition to a feed on compounds like fatty acids and polyphenols using an in vitro simulation of the digestive tract of the tilapia. The influence on fatty acids was determined by changes in the peroxide index, with the feed including PO presenting values four times higher than those of the control feed. On the other hand, the in vitro digestive simulation also evidenced an effect of PO on the bioaccessibility of polyphenols significantly influenced by the total digestion time and temperature. The bioaccessibility of polyphenol ranged from 2.09 to 16.23 μmol of the total Trolox equivalent antioxidant capacity for the combinations evaluated in the study. The greatest bioaccessibility was observed at the central point under the following conditions of digestive hydrolysis: pH of 7, 30 °C, 4.5 h of digestive hydrolysis and an absence of PO. [ABSTRACT FROM AUTHOR]

Phosphorus is an essential mineral present in the vegetable matter in the form of phytate, which is considered an antinutritional factor. Phytate can be degraded by phytases, which have been used in commercial feeds. However, these enzymes undergo costly isolation and purification processes. In the present study, a genetically modified (GM) Bacillus subtilis strain that expresses a fungal phytase was used as a feed additive. The GM probiotic was added to the commercial feed of shrimp Litopenaeus vannamei and its effects on zootechnical performance, proximate composition of muscle, lipid concentration in hepatopancreas, and expression of genes related to digestion, amino acid metabolism, and antioxidant defenses were analyzed. Although the genetically modified probiotic had no impact on growth parameters, there was a 39% increase in phosphorus content in muscle. In addition, genes related to digestion were downregulated in shrimp hepatopancreas, as well as an increase in lipids in this tissue. These results demonstrate that the GM probiotic increased the efficiency of the use of plant-derived phosphorus, which may imply a decrease in the addition of this element in the diets, as well as minimizing the impact of shrimp farms on the eutrophication of adjacent ecosystems. [ABSTRACT FROM AUTHOR]

The global production of aquatic organisms has grown steadily in recent decades. This increase in production results in high volumes of by-products and waste, generally considered to be of low commercial value and part of them are consequently discarded in landfills or in the sea, causing serious environmental problems when not used. Currently, a large part of the reused aquaculture waste is destined for the feed industry. This generally undervalued waste presents an important source of bioactive compounds in its composition, such as: amino acids, carotenoids, chitin and its derivatives, fatty acids and minerals. These compounds are capable of offering numerous benefits due to their bioactive properties. However, the applicability of these compounds may be opportune in several other sectors. This review describes studies that seek to obtain and apply bioactive compounds from different sources of aquaculture waste, thus adding commercial value to these underutilized biomasses. Volume of aquaculture industrial waste from crustaceans and mollusks. Quantity and quality of bioactive components in aquaculture waste. Applications of recovered proteins, lipids, chitin, carotenoids and minerals. Future prospects for the destination of aquaculture waste. [ABSTRACT FROM AUTHOR]

Several methods are used to recover compounds from these residues. Among them, ultrasound extraction has gained prominence due to its cellular disruption power. This work aimed to verify the action of ultrasound in increasing the yield of protein hydrolysate extraction from Pacific white shrimp (Litopenaeus vannamei) by-products. Proximal composition, hydrolysis degree, total content of carotenoids, and antioxidant activity (DPPH, ABTS, and reducing power) of the obtained hydrolysate was determined. The study found that the use of ultrasound concentrated more carotenoids, containing high antioxidant activity, increased the degree of hydrolysis, and accelerated the hydrolytic reaction rate. [ABSTRACT FROM AUTHOR]

Innovation in aquaculture nutrition is linked to the use of new compounds, in order to achieve a more sustainable production. The grapefruit industry is one of the biggest in the fruit sector due to the enormous wine and juice production. As a consequence, tons of grape bagasse (GB) turn into waste every year, a product rich in antioxidants such as polyphenols (PPS). Shrimp Litopenaeus vannamei is generally cultured under stressful conditions such as crowding, which can increase the production of reactive oxygen species (ROS) and could benefit from feed with functional properties. Five isoproteic and isolipidic diets were formulated: GB0, GB2.5, GB5, GB10 and GB15% of GB inclusion; those diets were tested in triplicate. Shrimp juveniles (0.35 ± 0.01 g) were stocked at a density of 150 shrimp m−3, and fed for 45 days. At the end of the experimental period, hepatopancreas and muscle samples of shrimp were collected for the determination of the antioxidant capacity against peroxyl radicals (ACAP), thiobarbituric acid‐reactive substances (TBARS) and PPS content. The results indicate that it is possible to add up to 2.5% of GB inclusion without affecting growth and feed conversion rate significantly. Also, the shrimps muscle of the GB15 treatment presented the highest PPS concentration and the lowest lipid peroxidation. In conclusion, it is possible to include GB in shrimp diets in small amounts, despite not obtaining significant antioxidant benefits. [ABSTRACT FROM AUTHOR]

Cyanobacteria are a rich source of nutrients in addition to producing bioactive compounds capable of stimulating the immune system of hosts. Also, they can be manipulated with relative ease to produce heterologous proteins. In the present study, a strain of Synechococcus elongatus (PCC7942) was manipulated to produce a prokaryotic β-glucosidase. This strain was added to the diet of Pacific white shrimp Litopenaeus vannamei for 45 days and parameters such as growth performance, proximate composition of muscle tissue and expression of genes related to digestion, amino acid metabolism, immune system and antioxidant defenses were evaluated. Histology of shrimp hepatopancreas was also performed. Transgenic cyanobacteria did not produce negative effects on shrimp growth performance. Regarding proximate composition, an increase in lipid and phosphorus deposition was observed in the muscle of shrimp, as well as lipid in hepatopancreas. Furthermore, an increase in expression of genes related to the immune system (tgase) as well as carbohydrate metabolism and amino acid metabolism (gdh) was observed. It was observed also that both strains of cyanobacteria (wild and transgenic) produced effects on carbohydrate metabolism (increased amy expression) and digestive system (decreased cathB expression). It is possible that cyanobacteria in the diet may be serving as a source of carbohydrates, reducing the use of proteins as a source of energy. It can be concluded that transgenic cyanobacteria had a beneficial effect on shrimp by increasing lipid deposition in muscle and hepatopancreas as well as phosphorus absorption from feed, which can minimize the environmental impact of shrimp farms. [ABSTRACT FROM AUTHOR]

Bioaccessibility of aflatoxin B1 (AFB1) found in contaminated peanut meal was assessed by an in vitro system that simulated conditions of Nile tilapia (Oreochromis niloticus) intestine. Peanut meal containing 17.1 µg kg−1 AFB1 was used as substrate. Reference assays were carried out with intestinal enzyme extracts from adult tilapia under realistic physiological conditions of enzyme/substrate ratio (0.21 U mg−1), pH (8.2), and temperature (25 °C). Different factors that could potentially affect bioaccessibility of AFB1 were evaluated: total digestion time (3 to 6 h), relative amount of substrate (250 to 750 mg), and amount of rice husk used as adsorbent (1:1 and 1:2, peanut meal/rice husk). AFB1 released after digestive hydrolysis was extracted by QuEChERS and quantified by a multi-reader. Bioaccessibility of AFB1 increased with digestion time (from 36 after 3 h to 100% after 6 h) and with the amount of substrate. In contrast, rice husk reduced bioaccessibility of AFB1 by 28 and 20% in ratios of 1:1 and 1:2, respectively. Therefore, this study suggests not only that in vitro assays may be used as prospective assays to evaluate bioaccessibility of AFB1 under species-specific digestive conditions, but also that inclusion of rice rusk in feed may be a promising tool to reduce mycotoxin bioaccessibility. [ABSTRACT FROM AUTHOR]

This work investigates the effect of adding different sources of organic carbon in biofloc systems on water quality, microorganisms' density and zootechnical performance of juvenile Mugil liza raised in the biofloc system indoors over 45 days. Fish (±7.99 g) were stored at a density of 15 fish per tank and fed a commercial feed of 42% protein. The study was arranged in three treatments according to the carbon source: dextrose—DE, liquid molasses—LM and rice bran—RB, and one control with no bioflocs (clear water—CW), all in triplicate. The treatments had no influence (p > 0.05) on the performance parameters of the animals, survival (over 90%), as well on the productivity (between 0.35 and 0.6 kg/m3). Overall mean of total ammonia was lower (p < 0.05) in the biofloc systems than in clear water (CW). Nitrite average was lower (p < 0.05) in the bioflocs fertilized with LM and RB carbon sources, having a concentration of 1.3 ± 1.9 mg/L and 0.6 ± 0.6 mg/L respectively. RB also had the smallest range in nitrite levels throughout the study, from 0.04 to 2.5 mg/L. The LM and RB provided a greater (p < 0.05) abundance of total adhered and coccus bacteria. Water consumption was higher (p < 0.05) in the CW (1.87 m3 per tank) compared with the biofloc treatments (0.41 and 0.44 m3 per tank). Liquid molasses contributed to maintaining water quality compared with clear water, providing savings of around 80% of water. [ABSTRACT FROM AUTHOR]

In the field of shrimp aquaculture, the utilization of probiotics represents a promising avenue, due to the well-documented benefits conferred by these microorganisms. In the current study, a Bacillus subtilis strain, referred to as strain E, was isolated from the gastrointestinal tract of the shrimp Litopenaeus vannamei and subsequently identified via molecular methods and phylogeny. The probiotic potential of strain E was characterized, and its application as a feed shrimp additive was evaluated in a 45-day experiment. Several parameters were assessed, including zootechnical performance, muscle tissue proximate composition, hepatopancreas lipid concentration, and the expression of genes associated with digestion, amino acid metabolism, and antioxidant defense mechanisms in various shrimp tissues. Although no significant impact on zootechnical performance was observed, supplementation with strain E led to an increase in lipid concentration within both muscle and hepatopancreas tissues. Furthermore, a marked decrease in the expression of genes linked to digestion and amino acid metabolism was noted. These findings suggest that the addition of the B. subtilis strain E to shrimp feed may enhance nutrient absorption and modulate the expression of genes related to digestion and amino acid metabolism. [Display omitted] • B. subtilis strain E was isolated from the gastrointestinal tract of L. vannamei ; • Strain E showed probiotic potential and was used as a supplement in shrimp feed; • Shrimps fed with strain E had increased lipid content in muscle and hepatopancreas; • Strain E diet downregulates genes related to digestion and amino acid metabolism. [ABSTRACT FROM AUTHOR]

Abstract: Nutritional values of microbial floc meal and soy protein concentrate were evaluated as alternative protein sources to fishmeal in diets for Litopenaeus vannamei juveniles. A feeding trial was conducted during 28days to investigate the effects of partial and total replacement of fishmeal with microbial floc meal and soy protein concentrate on feed intake and growth of L. vannamei. Five diets were formulated to contain 38% crude protein and 17kJ/g gross energy. Microbial floc meal was obtained from super-intensive shrimp farm effluent. A control diet (with fishmeal as the main protein source) was compared to four diets containing microbial floc meal and soy protein concentrate at 25%, 50%, 75% and 100% replacement levels and a commercial diet. This feeding trial was conducted in a recirculating aquaculture system, utilizing shrimps weighing 2.48±0.29g. The weight gain, final weight, feed conversion ratio, specific growth rate, protein efficiency ratio and survival were not significantly different among treatments, suggesting that fishmeal can be completely replaced with soy protein concentrate and microbial floc meal without adverse effects on L. vannamei performance. These results suggest that a mixture of soy protein concentrate and microbial floc meal can be utilised as a substitute for fishmeal in diets for L. vannamei juveniles. [Copyright &y& Elsevier]

The effects of cyclical feeding restriction (3, 4, 5, 6, and 7 days of feeding per week) on the performance of juvenile Nile tilapia (Oreochromis niloticus) in a biofloc technology system (BFT) were evaluated in this study for 77 days. Fifteen experimental units (400L) with temperature control (mean 28.2 °C) randomly distributed 1500 fish (0.42 ± 0.02 g). Fish were fed commercial feed (46.7 g of crude protein and 4475.5 kcal kg−1 of gross energy) up to satiation. Feeding cycles with different restrictions (p < 0.05) influenced animal growth but not survival and final density (p > 0.05), which remained around 94% and 235 fish.m−3, respectively. Juveniles fed 6 days a week showed 1.25 of feeding efficiency, while animals fed 3 days a week (more restricted) showed hyperphagia but did not exhibit compensatory growth. Changes in the morphology of hepatocytes (presence of vacuoles, displacement of the nucleus to the periphery, and fatty degeneration) were observed with an increase in feeding days, and a high degree of hepatic steatosis (p < 0.05). Water quality parameters remained within acceptable limits for the species and system operation. Feeding regimes influenced the characteristics of bioflocs (total suspended solids and porosity) and the abundance of microorganisms (p < 0.05). Nutritionally, less restricted diets (6 and 7 days of feeding per week) produced more protein (38.3 and 40.6% CP) and energy bioflocs (2252.8 and 2313 kcal.kg−1) (p < 0.05), while protein, lipid, and body energy were significantly lower (p < 0.05) with the more restricted diet. The composition of microorganisms was influenced by the feeding regimes (p < 0.05). Results demonstrated that the occurrence of total compensatory growth (6 days of feeding per week) represents an economic advantage with a reduction of 26.8% of feed and greater profitability in the unitary commercialization of tilapia juveniles. [ABSTRACT FROM AUTHOR]

In this study Aflatoxin B1 (AFB1), ochratoxin A (OTA) and zearalenone (ZEN) occurrence in fish feed, regarding its chemical composition, were investigated. Besides, AFB1 bioaccessibility to fish was evaluated by in vitro digestion. Mycotoxins were extracted by QuEChERS and quantified by HPLC-FLD. Results showed that 93.3% of the samples were contaminated at maximum levels of 16.5, 31.6, and 322 µg/kg in the cases of AFB1, OTA, and ZEN, respectively. A positive correlation between OTA, ZEN contamination, and lipid content was observed. Risk estimation of feed consumption by fish at the highest levels of AFB1, OTA, and ZEN shows that the younger the fish, the higher the risk of exposure to mycotoxins. The AFB1 bioaccessibility assay showed that 85% of this mycotoxin may be absorbed by fish. Therefore, establishing maximum levels in the fishing sector is fundamental to contribute to feed quality and nutritional safety of fish species. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of dietary inclusion of lyophilized açaí Euterpe oleracea (LEO) on redox status of shrimp Litopenaeus vannamei (initial weight 1.5 ± 0.39 g) upon exposure to cyanotoxin nodularin (NOD) in bioflocs system. Three hundred juvenile shrimps were randomly divided into two groups and fed twice a day with two diets: one containing 0.00 (control diet) and the other 10.0% LEO (w/w) for 30-days. After the feeding period, both shrimp groups were submitted to three treatments (14 L; 7 shrimp/tank) with different concentrations of cyanotoxin NOD (0.00; 0.25; and 1.00 μg/L) dissolved in water with 96 h of exposure. Then, the shrimps were sampled (n = 15/treatment) for the determination of reduced glutathione (GSH), the activity of glutathione-S-transferase (GST), sulfhydryl groups associated to proteins (P-SH), and lipid peroxidation (TBARS) in the hepatopancreas, gills and muscle. The NOD accumulation was measured in the muscle. The results revealed that dietary LEO significantly increased GSH levels in the hepatopancreas and gills of the shrimps exposed to NOD. Toxin exposure did not modify GST activity in all organs. Muscle TBARS levels were lower in the shrimp fed with the LEO diet and exposed to NOD. The NOD toxin did not accumulate in the muscle but notably was detected in the control groups fed or not with dietary LEO. Açaí was able to induce the antioxidant system of L. vannamei , as well as lowered the oxidative damage in shrimps exposed to NOD, suggesting its use as a chemoprotectant against cyanotoxins. • It was evaluated the use of açaí Euterpe oleracea as a chemoprotectant. • Shrimps L. vannamei were exposed to cyanotoxin nodularin (NOD). • Açaí increased glutathione levels in shrimps exposed to NOD. • Açaí lowered the oxidative damage in shrimps exposed to NOD. [ABSTRACT FROM AUTHOR]

This study investigated the effects of the inclusion of Mauritia flexuosa fruit pulp in the diet on the growth performance, economic benefit, muscle composition, total contents of carotenoids and flavonoids, chromaticity parameters, total antioxidant capacity, and lipid peroxidation in the hepatopancreas and muscle of the juvenile shrimp Litopenaeus vannamei (weighing 1.26 ± 0.023 g). Five diets (37% protein, 10% lipid) consisting of 0 (control), 1.25%, 2.50%, 5.00% and 10.00% (w/w) M. flexuosa fruit pulp were formulated and provided to the shrimps (n = 50 per tank, treatments in triplicate) for 31 days. Results showed that there were no significant differences between the treatments in terms of the growth capacity, chromaticity parameters, muscle composition and total flavonoid content of shrimps (p >.05). However, the carotenoid content in the muscle and hepatopancreas of the shrimps was significantly increased due to the dietary carotenoids present in M. flexuosa fruit pulp (p <.05). This increase in the carotenoid content directly favoured the increase in the antioxidant capacity in the hepatopancreas and muscle of the shrimps (R2 = 0.99 and R2 = 0.97 respectively; p <.05). There was also a direct relationship between the carotenoid content and the decrease in lipid peroxidation in the hepatopancreas (R2 = 0.90; p <.05). The feed cost kg−1 in terms of weight gain and protein production decreased with the inclusion of high levels of M. flexuosa fruit pulp, reaching 8.11% and 18.76% of cost reduction, respectively, with the addition of 5.00% of M. flexuosa fruit pulp. Therefore, the inclusion of M. flexuosa fruit pulp in the diets of shrimp can increase the carotenoid content and the antioxidant capacity in the hepatopancreas and muscle, reduce lipid peroxidation in the hepatopancreas, and probably provide economic benefits for the rearing of juvenile shrimps. [ABSTRACT FROM AUTHOR]

This study investigated the effects of the use of the inclusion of açaí on the diet of shrimp Litopenaeus vannamei on antioxidant and histopathological responses after exposure to ammonia. The shrimps were fed two experimental diets: control and with 10% of açaí inclusion (W/W), for 35 days. Afterwards, the organisms were exposed at four concentrations of ammonia (0.01‐control; 0.26; 0.48 and 0.91 mg NH3‐N L−1) for 96 hr. The total antioxidant capacity (ACAP) of the gills decreased significantly in both diets when exposed to ammonia, whereas in the muscle, the açaí promoted an increase in ACAP. Concomitantly, lipid peroxidation levels increased in the gills and decreased in muscle. After exposure to ammonia, glutathione‐S‐transferase activity increased in hepatopancreas in shrimps fed with açaí facilitating the detoxification of lipid peroxidation by‐products, and the concentration of protein sulfhydryl groups decreased in the gills and muscle of the shrimp of the control diet, evidencing protein damage, an unobserved response in shrimps that received the açaí diet. Histopathological changes decreased in açaí‐fed shrimps about the control diet after exposure to ammonia. It is concluded that açaí mitigated ammonia‐induced histopathological changes, improved the antioxidant defence system (gills and muscle) and attenuated the lipid damage in the muscle. [ABSTRACT FROM AUTHOR]

With the productive intensification of fish farming, the partial or total replacement of fishmeal by ingredients of plant origin became a reality within the feed industry, with the aim of reducing costs. However, this practice increased the impact of mycotoxin contamination. Studies have shown that mycotoxins can induce various disorders in fish, such as cellular and organic alterations, as well as impair functional and morphological development, and, in more severe cases, mortality. Thus, studies have been conducted to evaluate and develop strategies to prevent the formation of mycotoxins, as well as to induce their elimination, inactivation or reduction of their availability in feed. [ABSTRACT FROM AUTHOR]

Although aquaculture is among the fastest growing food production sectors in the world, one of the bottlenecks for the continuity of its expansion is the dependence of animal protein on commercial feed formulations. Vegetable proteins are an alternative due to the low cost and high availability. However, this protein source is accompanied by a series of antinutritional and pro-inflammatory compounds, including phytate. Phytases can be added in feed for phytate degradation and increase nutrient availability. However, the use of purified phytases significantly increases the production costs. An interesting alternative is to use probiotics genetically modified as bioreactors for phytase production. In the present study, a strain of Bacillus subtilis secreting a fungal phytase was used to evaluate the effect of a feed with high content of soybean meal on zebrafish (Danio rerio). We analysed the condition factor (K) of fish, and the expression of genes related to the immune system, inflammatory response and oxidative. stress. The results obtained demonstrate that the transgenic probiotic was efficient in improving the fish condition factor, stimulating the immune system, reducing the inflammatory response and oxidative stress. Thus, probiotics acting as phytase bioreactors can be considered an interesting tool for the adaptation of commercial species to feed of lower cost. • Vegetable proteins are a low cost alternative for commercial feed used in aquaculture. • Phytate is an antinutritional compound associated to vegetable matter. • Phytases can degrade phytate and increase nutrient availability. • Bacillus subtilis can be manipulated to secrete recombinant phytase. [ABSTRACT FROM AUTHOR]

The addition of pure carotenoids is a common practice in some aquaculture species production since its use in fish feed is known to improve carcass and antioxidant capacity. Spirulina (Arthrospira) cyanobacteria are a rich source of carotenoids that has proven health benefits for fish welfare. In the current experiment, four isonitrogenous (38%) isolipidic (9%) diets were made, including a control diet (free of β-carotene and Spirulina, SP0), β-carotene diet (50 mg kg−1, β0), and two Spirulina (Arthrospira platensis) diets with 2% (SP2) and 4% (SP4) of total feed inclusion. The experimental diets were given to juvenile mullets in a controlled recirculation system. The parameters evaluated were growth, colour, total carotene content of muscle, and antioxidant capacity of the liver and muscle. Significant differences were found (p < 0.05) in the final weight, specific growth rate, and feed conversion ratio between the SP0 treatment and the β0, SP2, and SP4 treatments. The colorimetric analysis showed that the redness and carotene deposition in muscle of mullet is statistically the same between β0 and SP4. Mullets fed with Spirulina (SP2 and SP4 treatments) had a statistical higher antioxidant capacity against radical peroxyls in liver tissue, showing lower lipid peroxidation (TBARS). In conclusion, Spirulina can be a suitable substitute for pure β-carotene addition in fish diets, improving some of the health benefits from this carotene. [ABSTRACT FROM AUTHOR]

Five isonitrogenous and isolipidic diets were prepared with different inclusion levels of Gracilaria domingensis (GD; 0%, 5%, 10%, 15%, and 20%) with the objective to test its effects on growth and mullet immune system. The experimental diets were fed to juvenile mullet (Mugil liza, 0.42 ± 0.03g) for 60 days. The growth and expression of anti-CD3 and anti-CD4 primary antibodies for T lymphocytes were evaluated. Fish growth and feed conversion ratio decreased insignificantly by increasing GD levels up to 10% level, after which fish growth was significantly retarded. On the other hand, no significant difference was observed in granulocytes, lymphocytes, and monocytes values due to GD supplementation. Mullet fed with GD-enriched diets had a higher expression of anti-CD3 and anti-CD4 antibodies than those fed the control diet. It is concluded that a 5% inclusion level of G. domingensis in the diet increases immune competence without compromising fish growth. [ABSTRACT FROM AUTHOR]

Abstract This research evaluated the effect of the simultaneous substitution of fish meal and fish oil at 0, 30, 50, 70 and 100% (termed SS0, SS30, SS50, SS70 and SS100, respectively) with both Spirulina (Arthrospira platensis) and linseed oil. The effect on growth, colour, fatty acid (FA) profile, and liver and muscle antioxidant response in mullets (Mugil liza) were evaluated. A full substitution was not possible due to a final body weight reduction (p < 0.05). The colorimetric analyses showed an improvement in fillet colouration (p < 0.05). Also, we found a saturation of carotenoids in muscle at 30% substitution. The content of highly unsaturated fatty acids - HUFA (DHA, EPA and ARA) in muscle diminished as the substitution level increased and, at the same time, the level of these FAs in the diet diminished. We found interesting evidence of elongation from 18:3n-3 to 20:3n-3 when substitution with linseed oil levels was above 50% but no desaturation to 20:4 or 20:5n-3 was found, which could insinuate a certain n-3 HUFA requirement under the experimental conditions. Moreover, we noted an increase in the antioxidant capacity up to the treatment SS70; the SS100 treatment showed a diminution in the antioxidant capacity. It is concluded that a partial inclusion of Spirulina and linseed oil (50%) is possible, and that this replacement can increase antioxidant responses, improve its growth performance and can modulate the mullets fillet quality without affecting negatively fillet fatty acid content. Graphical abstract Mugil liza juveniles were fed diets with different levels of simultaneous substitution (SS) of fish meal and fish oil with Spirulina and linseed oil. Unlabelled Image Highlights • Simultaneous substitution of fishmeal and fish oil with Spirulina and linseed oil was assessed using Mugil liza juveniles • Partial inclusion of Spirulina and linseed oil (50%) is possible without hampering Mugil liza survival and growth • Full simultaneous substitution is not feasible probably as a result of the lack of some essential amino acids • We have found evidence of fatty acid elongation in the muscle of mullets. [ABSTRACT FROM AUTHOR]

Background: Cyanobacterium Athrospira platensis (Spirulina) is a potential fishmeal (FM) substitute in fish diets because of its high protein content, antioxidant and immunostimulant properties. Objective: To evaluate the effects of total and partial substitution of FM with A. platensis (0, 30, 50, 70 and 100% substitution) in juvenile mullet (Mugil liza). Methods: Juvenile mullets (n=210) were maintained in a recirculation system under optimal water parameters for the species. Mullets were fed five experimental diets for 80 days. Each diet was tested in triplicate tanks. At the end of the experimental period growth parameters were measured and samples of blood, liver and spleen were taken to evaluate the immune system. Results: Full replacement (100%) of FM resulted in growth deficits and low survival. The FM replacement induced changes in the proportion of macrophages and lymphocytes. Up to 50% FM replacement increased the expression of CD3 receptors in spleen T lymphocytes (T-Cells), whereas >50% FM replacement decreased the expression of CD3 receptors. We also found that partial FM substitution diminished the apoptotic process. Conclusions: Up to 50% FM substitution with A. platensis can improve performance of non-specific immune system of mullets. [ABSTRACT FROM AUTHOR]

The effects of salinity on growth and parameters related to osmoregulation and energy turnover were evaluated in juvenile pompano Trachinotus marginatus . In a first experiment, fish were reared at different salinities (4, 8, 12, 16 and 20 ppt) for 15 days. No fish mortality was observed. Also, no significant difference in fish size (length and weight), hematocrit and plasma glucose concentration was observed among treatments. Although a significant increase in plasma Na + , Cl − and K + concentrations was noted with increasing water salinities, while no significant changes in plasma osmolality were observed. The isosmotic point was calculated as 357.5 mOsm/kg H 2 O, corresponding to the osmolality of the ambient water at salinity 13.1 ppt. These findings indicate that juvenile pompanos T. marginatus acclimated to 20 ppt are fully acclimated to a wide range of salinities (4–20 ppt) after 15 days of transfer to the new salinity condition. Also, they show that the plasma isosmotic point of juvenile T. marginatus (13 ppt) is within the range of values reported for some euryhaline teleost fish from different habitats (10–14 ppt). In a second experiment, fish were reared at different salinities (3, 6, 12 and 32 ppt) for 28 days. No significant difference in survival, feed conversion, Fulton's condition factor, body weight coefficient of variation, feed intake and intestinal trypsin activity was observed among salinity treatments. However, fish reared at 32 ppt showed lower body weight, specific growth rate, oxygen consumption, and gill Na + ,K + -ATPase activity than those reared at 3 and 6 ppt. Also, their gills showed higher chloride cell area, epithelium thickness, chloride cell density and mucous cell density than those of fish reared at 3, 6 and 12 ppt. These findings indicate that juvenile pompano T. marginatus is euryhaline in the range of salinities tested (3–32 ppt) and grows better when reared at low salinities (3–6 ppt) for 28 days. This performance is associated with a good osmoregulatory ability resulting from structural and biochemical adaptive responses of the gill epithelium to salinity changes paralleled by increased aerobic metabolism and elevated use of liver carbohydrate store. Although it would be cost effective to maintain higher salinities in coastal aquaculture systems given the proximity to the marine environment, our findings support the idea of rearing juvenile pompano T. marginatus in low salinities (3–6 ppt) to improve growth. Statement of relevance Pompano rearing performance is improved in low salinities. [ABSTRACT FROM AUTHOR]

The current study aimed to evaluate the influence of lipoic acid (LA) supplementation (439.84 ± 6.71 mg LA/kg feed) on antioxidants responses throughout the time in intestine, liver and muscle of juvenile common carp Cyprinus carpio . Two experimental groups were fed during four weeks with a diet with or without LA. Glutathione-S-transferase (GST) activity, glutathione (GSH) content, antioxidant capacity against peroxyl radicals (ACAP) and lipid peroxidation (TBARS) were evaluated in these organs. Also, a technique to measure protein disulfide bonds and sulfhydryl groups was optimized for intestine samples. GST activity was significantly higher (p < 0.05) in intestine after two weeks of supplementation. GSH content was also significantly higher (p < 0.05) in intestine, liver and muscle of fish fed with LA after two and three weeks, respectively. Total capacity antioxidant against peroxyl radicals was significantly increased (p < 0.05) in the muscle of animals fed with LA after the fourth week. Concentration of disulfide bonds was higher in the intestine of fish fed with LA but this group also showed higher concentration of sulfhydryl groups (p < 0.05). It is concluded that supplementation with LA is a safe strategy to induce antioxidant responses and improves the antioxidant status in different organs of common carp. Two week of supplementation are required to induce antioxidant responses in intestine and liver and three week for muscle. [ABSTRACT FROM AUTHOR]

The study aimed to evaluate the use of increasing levels of defatted rice bran fermented by Rhizopus oryzae in the diets of juveniles of mullet fish Mugil liza , assessing growth parameters, proximal carcass composition, and lipid peroxidation (TBARS) in the liver and intestine. Six experimental diets were formulated: a control treatment without rice bran, a second treatment with the inclusion of 200 g kg−1 of defatted rice bran without fermentation (DRB200), and the remaining treatments received diets with the inclusion of 100, 200, 300, or 400 g kg−1 of fermented bran. The experimental design used 216 mullet juveniles (2.10 ± 0.04 g) randomly distributed in a recirculation system composed of 18 tanks, divided into six treatments and three replications, with 12 fish per experimental unit. During the experiment, fish were fed ad libitum three times a day, for 50 days. No mortalities were recorded during the experimentation. The performance variables showed that an inclusion equal or higher than 200 g kg−1 of fermented rice bran resulted in decreased growth. Furthermore, in carcass proximal composition, the lipid content decreased with higher inclusion levels of fermented rice bran and the control treatment showed the highest lipid content, while the ash content of fish carcasses increased with the higher inclusion of the tested ingredient. No differences were recorded for TBARS in the liver and intestine. According to the results, we recommend a maximum inclusion of 100 g kg−1 fermented rice bran in diets for M. liza juveniles. • Fermentation of rice bran by Rhizopus oryzae fungus improved by 32% the amount of protein. • Defatted Rice Bran fermented can be included up to 100 g kg−1 for mullet without compromising growth performance. • Inclusions equal to or greater than 200 g kg-1 have an adverse effect on growth, but not on flesh quality. [ABSTRACT FROM AUTHOR]

Fish are potentially submitted to water acidification when reared in recirculating aquaculture systems. This study evaluated the responses of juvenile cobia Rachycentron canadum after acute exposure to acid water. Juvenile cobia (12.6 ± 0.5 g; 14.2 ± 0.2 cm) were acutely exposed to four pH levels (7.9 (control), 6.5, 6.0, and 5.5). After 24 h of exposure to different pH values, fish were sampled for physiological and histopathological evaluation. Acid water affected physiological parameters and induced morphological histopathologies on gill and skin of juvenile cobia, and these effects were more conspicuous with decreasing pH values. Acid stress induced blood acidosis in juvenile cobia, coupled to a decrease in bicarbonate ( HCO3−) and saturated O2 (s O2) in fish blood. On the other hand, haematocrit, haemoglobin and glucose concentration increased their values ( P < 0.01) comparing to control level. Hyperplasia with completely fusion of secondary lamella was observed in all pH treatments (6.5. 6.0 and 5.5), while telangiectasia and proliferation of chloride cells were present for fish exposed to pH 6.0 and 5.5. In skin hyperplasia and hypertrophy of mucous cells, necrosis of these cells for fish exposed to pH 6.0 and 5.5 was observed. The results of this study demonstrate that acute acid water exposition affected physiology and histopathology in juvenile cobia, especially at pH values below 6.5. Accordingly, particular attention must be given to pH during cobia reared in recirculating aquaculture. [ABSTRACT FROM AUTHOR]

Abstract: The use of fishmeal (FM) and fish oil in aquafeeds is a major challenge in the development of aquaculture. The discovery of alternative ingredients for aquaculture feedstuffs will allow for the sustainable growth of this activity. The cyanobacteria Arthrospira (Spirulina platensis) contains high quality protein and also immune-stimulatory properties that have been tested in mammals, fish and crustaceans. The purpose of this work was to evaluate the growth and immunological parameters of the white shrimp Litopenaeus vannamei when it was fed experimental isonitrogenous diets (~35% protein), containing 0%, 25%, 50%, 75% and 100% cyanobacteria A. platensis replacing fishmeal for 50days. At the end of the experiment, there were no significant differences (p <0.05) in growth performance among the shrimp fed diets with up to 75% fishmeal replacement. The immunological parameters differed significantly in the percentage of hyaline and granular hemocytes in the shrimp fed the diets with at least 25% fishmeal replacement. The apoptotic index also showed highly significant differences, but only in those shrimp fed a diet consisting of 100% fishmeal replacement. The results showed that up to 75% of fishmeal could be replaced by A. platensis without affecting survival or creating a growth depression. Moreover, the smaller substitution level (25%) promoted an enhancement of the tested immunological parameters. [Copyright &y& Elsevier]

This study evaluated the effects of dietary supplementation with different concentrations of chitosan from shrimp tailings on the antioxidant and immune systems of juvenile Litopenaeus vannamei cultivated in a biofloc system (BFT) and subjected to abrupt salinity reduction. The experiment was performed with juvenile shrimp fed diets supplemented with four levels of chitosan: C0 (0 g kg−1 diet – control), C1 (1 g kg−1 diet), C3 (3 g kg−1 diet), and C5 (5 g kg−1 diet). After 35 days, the shrimp were exposed to an acute reduction in salinity from 30 to 5 for 24 h, and the hemolymph, gills, and hepatopancreas were collected. No significant differences were found in the growth performance and survival among treatments. In the gills, acute salinity reduction increased the activity of catalase (CAT), although this effect was reversed by the 5 g kg−1 diet (C5). Furthermore, glutathione-S-transferase (GST) activity was maintained at the basal level in shrimp fed a 1 g kg−1 diet (C1) but reduced in those fed C3 and C5. We also identified a reduction in lipid peroxidation in shrimp fed the C3 and C5 diets. In the hepatopancreas, the GST activities and glutathione (GSH) levels were higher in shrimp supplemented with chitosan, which showed a protective effect. Saline stress and chitosan supplementation did not affect differential hemocyte counts. In conclusion, the results of this study suggest that dietary intake of chitosan could enhance some antioxidant defenses of L. vannamei farmed in a BFT system. Thus, the inclusion of at least 1 g kg−1 chitosan could represent a good alternative to improve defense mechanisms and stress resistance, and it could also contribute to the development of sustainable aquaculture. • Salinity stress induced oxidative stress in shrimp cultivated in the BFT system. • Chitosan supplementation improved different antioxidant responses in both the gills and hepatopancreas of L. vannamei. • Chitosan reduced lipid peroxidation in the gills of shrimp subjected to salinity stress. [ABSTRACT FROM AUTHOR]

Aquaculture is an important sector of world food production for which the source of protein for commercial diets is a huge bottleneck. Vegetable proteins are cheaper, but are accompanied by antinutritional compounds like phytate. Phytases are enzymes produced in microorganisms capable of degrading phytate. The addition of purified phytases to commercial feed improves the nutrient bioavailability of vegetable matter. However, the production and purification of phytases has a high cost. An alternative is to genetically manipulate a probiotic bacterium to produce and secrete phytase directly into the host's digestive tract. In the present study, a strain of Bacillus subtilis was engineered to produce and secrete a fungal phytase. The fish fed with a high vegetable content supplemented with transgenic probiotic showed an improvement in the parameters analysed. These results were corroborated with the expression of genes related to peptide transport (slc15a1b and slc15a2), appetite (ghrl), somatic growth (igf1 , myod and myog) and bone metabolism (bglap). All the analysed genes were strongly induced in the group of fish treated with the transgenic probiotic, corroborating with the results observed for the parameters. This study shows, for the first time, that a transgenic probiotic expressing recombinant phytase is able to minimize the antinutritional effects of the high content of vegetal matter included in the fish diet. The results presented herein open the possibility of transgenic probiotics being used as bioreactors for the production of molecules capable of interfering in other physiological systems in fish. • Protein for commercial diets is a huge bottleneck for aquaculture. • Plant proteins are accompanied by antinutritional compounds such as phytate. • Phytases improve the nutrient bioavailability of vegetable matter. • Since phytases have high cost, probiotic bacteria can be manipulated for enzyme secretion. • GM Bacillus subtilis minimized the antinutritional effects of phytate in zebrafish diet. [ABSTRACT FROM AUTHOR]