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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]

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]

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]

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]