BFT Treatments Research Articles

Effect of copepod Apocyclops dengizicus addition on growth, survival, and proximate composition of Macrobrachium rosenbergii postlarvae cultured in brackish‐water biofloc system

AbstractObjectiveThe effects of periodically adding the cyclopoid copepod Apocyclops dengizicus (every 4 days at a rate of 4 individuals/mL) with biofloc technology (BFT‐C) was compared with conventional biofloc technology (BFT; without copepod) or a clear‐water control for Macrobrachium rosenbergii postlarvae nursery culture.MethodsSurvival, growth, proximate composition, and economics of SMacrobrachium rosenbergii postlarvae was calculated. Water quality and biofloc proximate composition were also measured among treatments. For the BFT, maize starch was applied to achieve a C:N ratio of 20:1. Triplicate 125‐L polyethylene tanks containing 500 postlarvae each (9.40 ± 1.88 mg) were evaluated.ResultSpecific growth rate was significantly greater in the BFT‐C group (8.40 ± 0.24% per day) than BFT (7.23 ± 0.21% per day) and control (7.12 ± 0.42% per day) groups. Postlarvae survival was significantly increased with the BFT‐C (94.46%) treatment compared with the BFT (87.33%) and control (82.60%). A significantly lower food conversion ratio (1.08) was obtained in BFT‐C than both the BFT (1.73) and control (1.90), possibly due to significantly higher biofloc crude protein and lipid contents in the BFT‐C than BFT. Postlarvae whole‐body protein and lipid contents were significantly elevated in BFT‐C compared to the BFT and control treatments. Economics of gross return, net return, and cost‐benefit ratio were significantly better at BFT‐C than in either the BFT or control groups.ConclusionThis study indicates that copepod additions with BFT enhanced prawn postlarvae survival, growth, and whole body protein and lipid, as well as economics, which could augment productivity and sustainability in this industry.

Growth performance of critically endangered Hypselobarbus pulchellus in biofloc system: Influence of carbon sources on immune response, enzyme and antioxidant activity

We investigated the effect of various carbon sources on the production performance of critically endangered Hypselobarbus pulchellus in biofloc system. The experimental setup comprised four biofloc treatment groups with various carbon sources (jaggery, tapioca, rice and corn flour) and a control group. Healthy early fry (0.0068 g) was randomly stocked at 100 individuals per m3 into 15 circular fibre reinforced plastic (FRP) tanks (1000 l) and raised for 90 days. All the tested carbon sources significantly influenced weight gain, weight gain (%) and specific growth rate (SGR), with the jaggery treatment displaying the best growth performance (p<0.05). Fingerling survival rates varied from 93 to 95.67% (p>0.05). Compared to the control, the biofloc groups had significantly lower concentrations of nitrogen compounds, specifically total ammonia nitrogen, nitrite and nitrate concentrations were significantly lowered (0.29, 0.35 and 1.32 mg l-1, respectively) in jaggery treatment (p<0.05). In addition, the treatment using jaggery had a higher amount of plankton biomass and an abundance of the Bacillariophyceae group (80%). All biofloc groups displayed enhanced immune and antioxidant activity compared to the control. The jaggery treatment had elevated levels of lysozyme activity than other treatments (p<0.05). Furthermore, fingerlings raised in BFT treatments had significantly higher amylase, protease and lipase activity (p<0.05). Overall, this study’s findings suggest that the addition of various carbon sources significantly improves the production performance, with jaggery as the best carbon source for critically endangered H. pulchellus fingerling production in biofloc system to ensure sustainability. Keywords: Antioxidant activity, Fingerling, Heterotrophic bacteria, Jaggery, Specific growth rate, Sustainability

Enhancing Florida red tilapia aquaculture: biofloc optimization improves water quality, pathogen bacterial control, fish health, immune response, and organ histopathology across varied groundwater salinities.

Freshwater scarcity poses challenges to aquaculture worldwide, including countries like Egypt. In this study, we investigate the feasibility of integrating underground saline water (USW) with varying salinities into a Biofloc (BFT) system for desert mariculture of Florida red tilapia (FRT) and its impacts on water quality, fish performance and health. Four BFT treatments (C/N ratio = 15) were examined in triplicate using four salinity levels 0 ppt, 12 ppt, 24 ppt and 36 ppt, expressed as S0, S12, S24 and S36, respectively. For 75 days, a total of 12 fiberglass tanks (each 250L-1 water) were used to store FRT fry (average weight of 1.73 ± 0.01g/fish). The fish were fed an experimental diet (protein/fat = 30/5) and an additional carbon source of rice bran. The results revealed that group S12 showed better growth indicators, higher survival rate, lower FCR, and lower ammonia levels, while group S0 exhibited lower growth indicators (final weight, weight gain, and specific growth rate) than all groups. The serum kidney, liver, and antioxidant indices performed better in the S12 group. At 12 ppt, the immune-related parameter (IgM) increased by 22.5%, while the stress parameter (cortisol) decreased by 40.8% compared to the S0 group. The liver and intestinal histopathological results revealed that the S12 and S24 groups performed better. Pathogenic bacterial load counts favored the S24 group, which had the lowest number among the groups studied. The recommended salinity for FRT cultivation in USW and BFT is 19.94-20 ppt, determined by polynomial regression of FW and FCR.

The culture of Nile tilapia (Oreochromis niloticus) juvenile at different culture technologies: autotrophic, bioflocs and synbiotic

Nile tilapia is a widely produced species due to its rusticity and technological culture package. However, there is a knowledge gap in youth production using new technologies. Therefore, this work aimed to evaluate the production of juvenile Oreochromis niloticus in different culture technologies: autotrophic, synbiotic, and bioflocs, through of water quality parameters, plankton groups, bacterial counts and zootechnical performance. The experiment lasted 40 days, time needed to reach a commercial weight of juveniles, and used tilápia fry weighing 3.60 ± 0.32 g stocking density of 500 fish m−3 and fed with commercial feed (46% crude protein and 9% lipids). Before stocking the fish, the experimental units were prepared for 30 days with inorganic (potassium nitrate and superphosphate - autotrophic - AUT) and organic (sugar - bioflocs - BFT; rice bran fermented with probiotic - synbiotic - SYNB) addition and control group (CTL). Regarding water quality parameters, temperature, salinity, dissolved oxygen (DO) and pH were within those recommended for the culture of the species. The nitrogen compounds (TAN and N-NO2) and water footprint were lower in BFT and SYNB as compared than AUT and CTL. The phytoplankton community had significantly higher Bacillariophyta count in BFT and SYNB as compared than AUT and CLT, however Chlorophyta in AUT and Cyanophyta in BFT, SYNB and CTL, prevailed. Zooplankton showed dominance of Rotifera in all treatments, with higher values in SYNB and BFT (p < 0.05). BFT had the higher standard bacterial count, SYNB had the higher Bacillus sp. count, and AUT and CTL showed the lower microbial counts (p < 0.05). The zootechnical performance: final weight, yield, SGR, FCR, feed efficiency and Fulton condition factor were better (p < 0.05) in the BFT and SYNB treatments as compared than to the AUT and CTL. The FI (feed intake) did not show statistical differences between treatments (p > 0.05). Regarding survival, the lower (p < 0.05) was observed in the control treatment. Therefore, we can conclude that the BFT and SYNB systems are promising for improving the results of nitrogen compounds (TAN and N-NO2) control, water footprint, plankton community, bacterial and zootechnical production of juvenile Nile tilapia.

Different carbon sources and probiotics in biofloc based common carp (Cyprinus carpio) culture: Effects on water quality, growth performance, fish welfare and liver histopathology

AbstractThe current study investigated the combined effects of carbon sources and commercial probiotics on common carp welfare in a biofloc‐based system. Three hundred fingerlings (initial weight 43.2 ± 3.1 g) were distributed in 12 tanks including control, PR + BFT (rice bran + probiotics), PM + BFT (molasses + probiotics), and PC + BFT (corn starch + probiotics). After 12 weeks, the results showed that NNH3, NNO2, pH, and dissolved oxygen decreased in the PC + BFT and PR + BFT treatments when compared with the others. Unlike the control treatment, the fish reared in the biofloc treatments had significantly higher growth performances (p &lt; 0.05). The highest protein and lipid content in microbial flocs, protease, and lipase activity followed by protein and lipid muscle content was observed in PR + BFT when compared with PM + BFT and control (p &lt; 0.05). The sero‐immunological and antioxidant indices improved in the PC + BFT and PR + BFT treatments, and a significant difference was found than the control (p &lt; 0.05). The higher ductal dilatation was seen in PM + BFT treatment which is worth more investigation. Overall, the results revealed that adding probiotics to complex carbon resources improves the water quality and common carp fingerlings welfare in the biofloc system.

Interactive effects of culture systems (biofloc and clear water) and dietary protein levels on growth, digestive activity, mucosal immune responses, antioxidant status, and resistance against salinity stress in the Caspian roach (Rutilus caspicus) fry

This experiment aimed to evaluate effects of culture system and dietary protein level on performance of the Caspian roach fry. Fish (0.99 ± 0.06 g) were stocked into 12 tanks (water volume, 50 L) at a stocking density of 100 fish per tank. The experiment was designed with two culture systems (biofloc, BFT and clear water, CW) each with 38 and 28% dietary protein levels following a 2 × 2 factorial design. After 60 days, fifty fish were randomly captured from each tank and exposed to salinity challenge (13 g/L) for 72 h. On days 45 and 60, total ammonia nitrogen (TAN) values were significantly higher in CW treatments, then BFT38 treatment, and lower in BFT28 treatment. The final weight, weight gain, and SGR in BFT and CW38 treatments were significantly higher and FCR was lower than the CW28 treatment. The protein efficiency ratio was highest in the BFT28 treatment. Also, amylase, lipase, and protease activities in fish cultured in BFT system were significantly higher than the CW system. After salinity stress, skin mucus cortisol values were significantly lower and survival rate was higher in BFT groups compared to the CW treatments. After 72 h stress, the mucus glucose values in BFT and CW38 treatments were significantly lower than the CW28 treatment. Before stress, the mucus alkaline phosphatase (ALP) activity was lowest in the CW28 treatment. Skin mucus protease activity was significantly higher in BFT groups at before and all sampling times after salinity challenge. The skin mucus lysozyme activity and total protein value in all treatments increased at 24 h post stress, and then only returned to the pre-stress values at 48 h for the BFT38 treatment. After salinity stress, lysozyme activity in BFT and CW38 treatments was significantly lower than the CW28 treatment. After 48 h stress, the highest mucus ACH50 activity was observed in the BFT38 treatment, but it was not significantly different from the BFT28 and CW38 treatments. After salinity stress, muscle catalase and SOD activities were significantly higher and MDA content was lower in BFT treatments than the CW treatments, suggesting that biofloc can enhance the antioxidant defense in fish. Overall, biofloc system and high dietary protein level beneficially affect growth, skin mucus immune responses, and resistance against salinity challenge in fish. Also, microbial proteins contained in bioflocs as a supplemental protein source can compensate 10% reduction of protein in the Caspian roach fry diet.

Sodium metasilicate supplementation in culture water on growth performance, water quality and economics of indoor commercial-scale biofloc-based Litopenaeus vannamei culture

In super-intensive shrimp culture, water supplements are often used to adjust and stabilize water quality parameters, microbiological and environmental conditions, as well as suppress undesirable microorganisms. In addition, some water supplements are frequently utilized to boost the diatom population in water. These microorganisms are well known to enhance the shrimp growth performance, and present inhibitory effect against pathogenic vibrio. The present study evaluated the effect of sodium metasilicate (SM) supplementation in the culture water on the diatom population, water quality, zootechnical performance and economics of indoor commercial-scale biofloc-based culture. Litopenaeus vannamei (PL10, 4.1 ± 1.5 mg initial weight) were stocked in eight 500 m−2 commercial ponds with (BFT-SM) and without SM supplementation (BFT as a control), with four replicates per treatment. After 92 days (single phase, direct stock), the average values of silica (SiO2) were 8.2 mg L−1 in BFT-SM and 2.5 mg L−1 in BFT (control) (P < 0.05). Microscopical analysis indicated higher diatom dominance in BFT-SM, corroborated by higher chlorophyll-A concentrations. The shrimp biomass and yield were significantly higher in BFT-SM with 3.0 kg m−3 and 36.2 ton ha cycle−1 compared to BFT with 2.8 kg m−3 and 33.5 ton ha cycle−1, respectively. The BFT-SM treatment produced a 9.75% higher net profit margin than the BFT treatment and a 10.55% increase in revenue. Our study demonstrated positive impacts of SM supplementation on diatom population, resulting in enhanced shrimp performance and economic returns in indoor commercial-scale biofloc-based L. vannamei culture.

Evaluation of Effect of the Different Stocking Densities on Growth Performance, Survival, Water Quality and Body Indices of Pearlspot (Etroplus suratensis) Fingerlings in Biofloc Technology

Background: This experiment was conducted to evaluate the effect of different stocking density on growth performance, survival, water quality and body indices of E.suratensis fingerlings for 90 days at PRFF, Pazhaverkadu. Methods: Three different stocking densities are 100, 200, 300 no of fishes/m3. The fingerlings of pearlspot, E.suratensis with an average body weight of 5.05±0.03 g were stocked at a rate of SD-1 (100/m3), SD-2 (200/m3) and SD-3 (300/m3) culture for a period of 90 days. Result: The growth parameters were found to significantly decrease with increasing stocking density in the biofloc rearing system. Result of Nitrite and nitrate concentrations were significantly lower in the BFT treatment with lower stocking density than in higher stocking density (P less than 0.05). The highest mean body weight gain recorded in SD1 (42.37±0.04 g) followed by SD2 (29.98±0.08 g) and SD3 (20.85±0.06 g). BFT significantly increased fish specific growth rate and net yield. There was no significant difference in hematology analysis (in terms of white blood cell and red blood cell counts, hemoglobin and hematocrit levels), total superoxide dismutase activity of fish between different stocking density (P greater than 0.05). Second-order polynomial regression analysis of weight gain against pearlspot culture under lower stocking stocking density (100/m3) indicate that biofloc technology culture with lower stocking density can improve the growth performance and immune response and also the maintenance of good water quality and improvement of feed utilization of pearlspot.

Effect of the probiotic Lactococcus lactis on the microbial composition in the water and the gut of freshwater prawn ( Macrobrachium rosenbergii ) cultivate in biofloc

The prawns fed with Lactococcus lactis obtained 100% survival in the BFT and BFTPROB treatments compared to the CONT (80%). Regarding growth, it was observed in PROB and BFTPROB treatments, the organisms got greater weight (6.3 ± 1.6, 6.8 ± 1.3 respectively) compared to the other treatments. The effect of L. lactis in the bacterial community of Macrobrachium rosenbergii postlarvae (PL’s) with initial mean weight of 0.1 g, and length 1.4 cm in biofloc, was evaluated. A randomized experimental design was used: T1:BFT: biofloc; T2:BFTPROB:biofloc+probiotic; T3:PROB:probiotic; T4:CONT:control; all in triplicate with 60 PL's/treatment. On days 64 and 127, the weight and length of prawns were determined. 15 guts/treatment were extracted and water samples to obtain bacterial DNA. Massive sequencing of 16S rRNA gene of the samples was performed. Metagenomic analysis identified 17 bacteria classes in gut and water samples. The most abundant were Alphaproteobacteria, Gammaproteobacteria, Betaproteobacteria, Flavobacteria, Actinobacteria, and Clostridia with different benefits in the prawns' health. The bacterial community in the intermediate phase was different to the final, maybe for the colonization capacity of certain bacteria that developed in each treatment. However, L. lactis did not affect the microbial community in prawns' gut and culture water, it attributed to the displacement of the microbial community in biofloc and other probiotics, however it was observed a better prawns' growth and survival with biofloc and probiotic treatments.

An Arboriculture Treatment of Biochar, Fertilization, and Tillage Improves Soil Organic Matter and Tree Growth in a Suburban Street Tree Landscape in Bolingbrook, Illinois, USA

Background: Urban tree growth may be reduced due to poor urban soil conditions. Soil management to alleviate poor urban soil conditions often includes organic amendments, fertilization, and/or tillage. A 3-year experiment was conducted in an urban landscape in Bolingbrook, Illinois, USA, to test whether an arboriculture treatment with biochar, fertilization, and tillage could improve soil quality and tree growth. Methods: The urban landscape included 75 street trees (Gleditsia triacanthos, Ulmus parvifolia, and Acer rubrum) growing in compacted, fine-textured soils. Results: The results of this experiment suggest that the arboricultural treatment of biochar, fertilization, and tillage (BFT) may improve soil quality and urban tree growth. Relative height growth was significantly greater (P ≤ 0.05) for Acer rubrum trees with BFT treatment (+ 28.9%) compared to tillage alone (+ 13.3%). Total soil organic matter (SOM), particulate soil organic matter (POM), and a soil quality index (SQI) were significantly (P ≤ 0.05) greater in the BFT treatment (total SOM = 6.00%, POM = 9.73%, and SQI = 70.2) compared to the tillage treatment (total SOM = 5.29%, POM = 7.23%, and SQI = 60.8). The SOM responses to the BFT treatment appear to be relatively short-lived but correlated with measures of tree growth. Conclusion: This arboricultural treatment of biochar, fertilization, and tillage has potential to be used to improve soil quality and promote growth for trees growing in compacted, fine-textured soils in suburban street tree landscapes.

Grazing diverse combinations of tanniferous and nontanniferous legumes: implications for foraging behavior, performance, and hair cortisol in beef cattle.

A diversity of forages with different types and concentrations of nutrients and plant secondary compounds may lead to complementary relationships that enhance cattle performance and welfare. We determined whether grazing combinations of tanniferous legumes (Lotus corniculatus, birdsfoot trefoil [BFT], Onobrychis viciifolia, sainfoin [SF]), and alfalfa [ALF] (Medicago sativa) influence foraging behavior, performance, and hair cortisol concentration in beef cattle compared with grazing the same legumes as monocultures. Twenty-one pairs of heifers grazed three spatial replications of seven treatments: monocultures of BFT, SF, or ALF, and all possible two- and three-way choices among strips of these legumes: SF-BFT, ALF-BFT, ALF-SF, and ALF-SF-BFT in two periods of 25 d each (adaptation phase + experimental period) during two consecutive years. The lowest incidence of grazing events occurred in the BFT treatment (42.0% of the total scans recorded; P < 0.10), with the rest of the treatments ranging between 47.8% (SF-BFT) and 52.6% (ALF-SF) of the total scans recorded. Heifers selected a varied diet, preferring SF over BFT or ALF in a 46:27:27 ratio for the three-way choice, and in a 70:30 ratio for both two-way choices. Heifers preferred BFT over ALF (62:38 ratio) in a two-way choice. All treatments followed similar daily grazing patterns (P > 0.10), with two major grazing events (1 h after sunrise and 3 h before dark). No differences among treatments were observed for the number of steps taken by heifers on a daily basis, motion index, or the percentage of time heifers spent standing (1,599, 5,356, and 45.3%, respectively; P > 0.10), suggesting that heifers on choice treatments did not invest extra time in walking, searching, or patch switching activities relative to heifers grazing monocultures. Heifers grazing the three-way choice gained more body weight (1.27 kg/d) than the average gains observed for animals grazing in all legume monocultures (1.00 kg/d; P = 0.014) or two-way choices (0.97 kg/d; P = 0.007), suggesting a synergism among pasture species for the treatment with the highest diversity. No differences in hair cortisol concentration were observed among treatments, with values ranging between 1.4 (BFT) and 2.12 ng/g (three-way choice; P > 0.10). Thus, forage diversity has the potential to enhance animal performance without affecting grazing efficiency, likely explained by the spatial arrangement of the forage species presented in the study.

The Effect of Adding Molasses in Different Times on Performance of Nile Tilapia (Oreochromis niloticus) Raised in a Low-Salinity Biofloc System

Abstract This study aimed to evaluate the effect of adding molasses in different times on water quality, growth performance, body biochemical composition, digestive and hepatic enzymes of Nile tilapia in the biofloc system. Tilapia fingerlings (1.53 ± 0.14 g) were distributed in five treatments including control, BFT24 (adding molasses to the tanks every 24 h), BFT48 (48 h), BFT72 (72 h), and BFT96 (96 h) and reared for 37 days in fiberglass tanks (130 L), with a stocking density of one fish per litre. The results showed that highest increases in biomass (740.12 g) and survival (98.97%) were obtained in BFT24 treatment (P&lt;0.05). The body composition was affected by the experimental treatments so that the highest protein content was obtained in the BFT72 (P&lt;0.05). Digestive enzymes activities were significantly (P&lt;0.05) higher in BFT treatments than the control group. The current study showed higher biomass and survival ratio for Nile tilapia were observed in BFT24 treatment. The liver and digestive enzymes of Nile tilapia were affected by the different addition times of molasses to the rearing tanks.

Growth, body composition and antioxidant status ofLitopenaeus vannameijuveniles reared at different stocking densities in the biofloc system using inland saline groundwater

Growth, body composition and antioxidant status of Litopenaeus vannamei under zero water exchange biofloc-based culture system using inland saline groundwater (ISGW) were evaluated during the 60-day culture period in four varying stocking densities of 60 (T1), 100 (T2), 140 (T3) and 180 (T4) juvenile shrimps m−3. The carbon : nitrogen ratio was maintained at 15:1 using sugarcane molasses. Shrimp in the BFT treatments performed significantly better (P < 0.05) than control in terms of survival (98%-100%), weight gain (10.83 to 7.68g), feed conversion ratio (1.19 to 1.30) and feed efficiency ratio (0.88–0.84) at the end of the experimental period. Higher level of crude protein (29.1% to 33.0%), lipid (5.0% to 5.6%) and ash (1.4% to 1.6%) content was observed in the tissues of the shrimps from the BFT treatments when compared to control. Antioxidant enzyme activities such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) in gills, hepatopancreas and muscle were higher in the BFT treatments than in the control. These results indicate that microbial protein from recycled waste functions as nutrient, growth promoter and antioxidant capacity stimulator in shrimp reared in BFT using ISGW.

Effect of Brachionus plicatilis and Navicula sp. on Pacific white shrimp growth performance, Vibrio, immunological responses and resistance to white spot virus (WSSV) in nursery biofloc system

The purpose of this study was to evaluate the effect of Brachionus plicatilis and Navicula sp. addition on growth performance, Vibrio count, immunological responses and resistance to white spot syndrome virus (WSSV) of Litopenaeus vannamei in nursery biofloc system. The study was divided into two phases and four treatments were examined in the first phase: BFT (biofloc); BFT-N (addition of 10×104 cells mL−1 of Navicula sp.); BFT-B (addition of 30 org mL−1 of B. plicatilis) and; BFT-BN (addition of 10×104 cells mL−1 of Navicula sp. and 30 org mL−1 of B. plicatilis), all in triplicate and; the second phase included a viral challenge, also in triplicate. Shrimp (PL10, 2 ± 0,01 mg) were reared in biofloc system (fertilized with inorganic and anaerobic and aerobic carbon process with a microbial mix), for 45 days at a density of 3000 shrimp m-3, with controlled temperature, without water exchange and fed with commercial feed. The diatoms and rotifers were added every 10 days, and at the end, shrimp performance, water quality, Vibrio count and total hemocyte count were evaluated. After 45 days, 300 shrimp m−3 were challenged with WSSV (2.2 × 107 copies of WSSV μL−1 of DNA) for 9 days. The BFT-N, BFT-B and BFT-BN treatments had higher values of final weight (1.02 to 1.16 g) and yield (2.85 to 3.30 kg m−3) which were higher than the BFT (0.86 g and 2.46 kg m−3). There were no differences in water quality among treatments. Vibrio count from water samples was significantly lower at the end of experiment with significant decrease of non-sucrose-fermenting gram-negative bacteria. However, for hepatopancreas, the Vibrio count was significant higher at the end, however with significantly increase of sucrose-fermenting gram-negative bacteria (98 to 100%). There was no significant difference between the THC and hyalyne count for all treatments. Massive mortality rate was firstly achieved in BFT and BFT-B treatments in the second phase. However, all treatments reported complete mortality and WSSV infection was confirmed by nested-PCR and histopathologically, with lesions suggestive of WSD (presence of nodules and tissue deformations). The Navicula sp. and B. plicatilis addition contributed to better performance parameters of shrimp in the nursery biofloc system, although there was no significant effect on the WSSV resistance of shrimp. Absence of tissue degeneration in WSSV infected shrimp from BFT-N treatment indicated benefit of using diatoms under standardized conditions.

Comparison between recirculating aquaculture and biofloc systems for rearing juvenile common carp ( Cyprinus carpio ): Growth performance, haemato‐immunological indices, water quality and microbial communities

In a 2-month trial, four different aquaculture systems, viz., (a) rearing at 50% daily water exchange without filtration (WE), (b) biofloc system (BFT1), without water exchange or filtration, (c) biofloc system (BFT2), similar to BFT1 but 10% of daily feed deducted, and (d) recirculating system (RAS), without water exchange, were compared through monitoring water quality as well as measuring the growth, haematological and immunological indices of common carp (Cyprinus carpio). Metagenomics was also applied to characterize the microbial profile of the waters through screening 16S rDNA gene sequences. BFT systems demonstrated lower values of pH, dissolved oxygen but did higher concentration of total suspended solid (TSS) and 5-day biochemical oxygen demand (BOD5). No significant change was observed in haematocrit, haemoglobin, albumin, total protein and total cholesterol of the fish kept in all treatments. Metagenomics analysis revealed the highest abundance for Proteobacteria in BFT1, BFT2 and RAS systems, whereas Firmicutes was the dominant phylum in WE treatment. At the genus level, Flavobacterium (in BFT treatments), Sphingobacterium (RAS) and Rhodoluna (WE treatment) were the dominant bacteria. Taken together, BFT treatments could improve water quality and feed utilization. Moreover, BFT and RAS rearing conditions might change microbial structure of water.

Effect of bio-floc on water quality and the production performance of bottom and filter feeder carp fed with different protein levels in a pond polyculture system

A 90-day experiment was conducted with the aim of investigating the effect of bio-floc on water quality and the production performance of bottom and filter feeder carp fed with different protein levels in a pond polyculture system. For this purpose, three bioflocs treatments with carbohydrate referred to as ‘BFT-24% (24% feed protein)’, ‘BFT-27% (27% feed protein)’ and ‘BFT-30% (30% feed protein)’ and a control referred to as ‘CW-30% (30% feed protein)’ without carbohydrate addition were performed in three replicate enclosures (7 m × 7 m × 1.5 m) each. Young bottom feeder mirror carp (Cyprinus carpio specularis) and filter feeder bighead carp (Hypophthalmichthys nobilis) with initial mean individual body weights of 691.34 (± 6.73 g) and 327.13 (± 3.54 g), respectively, were stocked altogether in polyculture at biomass of 800 g·m−2 and 200 g·m−2 in the control and treatment enclosures. There was a significant positive correlation between the bioflocs volumes and water temperatures from 19.3–28.5 °C (P < 0.05). The pH values and the concentrations of total ammonia nitrogen (TAN), nitrite nitrogen (NO2-N), nitrate nitrogen (NO3-N), total inorganic nitrogen (TIN) and orthophosphate (PO4-P) in all the treatments of BFT were significantly lower than those in the control (P < 0.05), while the total alkalinity, the concentration of chlorophyll a and the chemical oxygen demand (COD) did not show significant differences among the treatments and the control (P > 0.05). The specific growth rates (SGR), survival rates (SR) and net yields (NY) of mirror carp did not show significant differences among the different treatments or from the control (P > 0.05). The total feed conversion rate (TFCR) of fish in the control was significantly higher than that of the fish in the BFT treatments (P < 0.05). The total protein efficiency ratios (TPER) of the fish in BFT-24% was significantly higher than that of fish in the control (P < 0.05). The activities of protease and amylase in the gut of mirror carp significantly increased with increases of feed protein levels in the BFT treatments (P < 0.05), while the digestive enzyme activity in the BFT treatments did not show significant differences compared with that in the control (P > 0.05). This study demonstrated that a protein-restricted diet did not affect the productive performance or body condition index of mirror carp and bighead carp in a BFT polyculture system with improved water quality.

Bacteroides fragilis Enterotoxin Induces Sulfiredoxin-1 Expression in Intestinal Epithelial Cell Lines Through a Mitogen-Activated Protein Kinases- and Nrf2-Dependent Pathway, Leading to the Suppression of Apoptosis.

Enterotoxigenic Bacteroides fragilis is a causative agent of colitis and secrets enterotoxin (BFT), leading to the disease. Sulfiredoxin (Srx)-1 serves to protect from oxidative damages. Although BFT can generate reactive oxygen species in intestinal epithelial cells (IECs), no Srx-1 expression has been reported in ETBF infection. In this study, we explored the effects of ETBF-produced BFT on Srx-1 induction in IECs. Treatment of IECs with BFT resulted in increased expression of Srx-1 in a time-dependent manner. BFT treatment also activated transcriptional signals including Nrf2, AP-1 and NF-κB, and the Srx-1 induction was dependent on the activation of Nrf2 signals. Nrf2 activation was assessed using immunoblot and Nrf2-DNA binding activity and the specificity was confirmed by supershift and competition assays. Suppression of NF-κB or AP-1 signals did not affect the upregulation of Srx-1 expression. Nrf2-dependent Srx-1 expression was associated with the activation of p38 mitogen-activated protein kinases (MAPKs) in IECs. Furthermore, suppression of Srx-1 significantly enhanced apoptosis while overexpression of Srx-1 significantly attenuated apoptosis during exposure to BFT. These results imply that a signaling cascade involving p38 and Nrf2 is essential for Srx-1 upregulation in IECs stimulated with BFT. Following this upregulation, Srx-1 may control the apoptosis in BFT-exposed IECs.

Comparative study on the performance of genetically improved rohu “Jayanti” and native rohu, Labeo rohita fingerlings reared in biofloc system

The experiment was designed to compare the growth performance, haematological parameters, digestive enzyme activities, carcass composition and survival of genetically improved Labeo rohita (Jayanti rohu) and native Labeo rohita fingerlings rearing under the biofloc system.One ccomparative experimental trial of 60 days was carried out using pearl-millet as a carbon source with a C/N ratio of 15:1 along with control. Results showed that the average TAN (mg/l) was significantly lower in biofloc treatments as compared to control. The growth of Jayanti rohu was significantly higher in biofloc treatments. Further FCR was also found significantly lower in Jayanti rohu as compared to native rohu. Better survival was found in BFT treatments as compared to control. Jayanti rohu showed the highest survival (100%) compared to native rohu (96.66%). Jayanti rohu exhibited the highest average body weight gain (4.30 ± 0.06) and the lowest FCR (0.91 ± 0.01) in biofloc based system as compared to weight gain (3.46 ± 0.04) and FCR (1.17 ± 0.01) of native rohu. Enzymes viz. amylase, protease and lipase showed significantly higher activities in Jayanti rohu as compared to native rohu in the BFT treatment, whereas, haematological parameters were also found significantly higher in Jayanti rohu and native rohu in BFT treatment compared to control. Carcass composition of the Jayanti rohu showed significantly higher protein level (21.53 ± 0.39) and lipid level (0.96 ± 0.02) as compared to native rohu. The study revealed that, genetically improved Labeo rohita (Jayanti rohu), appears to be a better suitable strain to culture under BFT systems compared to native rohu.

Evaluation of biofloc generation protocols to adopt high density nursery rearing of Penaeus vannamei for better growth performances, protective responses and immuno modulation in biofloc based technology

Biofloc (BFT) based nursery rearing system help provides an additional food source, healthy juvenile production with better survival and an avenue for nitrogen removal through eco-friendly approach. It should be cost and energy efficient with a quick turn over. However, many questions remain unanswered regarding mechanisms of action and induced antibacterial/antiviral immune responses in penaeid shrimp especially during nursery phase. The present experiment was designed to evaluate the effects of biofloc treatments generated and maintained through three approaches on growth performances, physico-chemical parameters, microbial dynamics, feed utilization and immunological assessments in P. vannamei nursery rearing. The experiment was conducted in 500 L FRP tanks stocked with PL-III stage of Pacific white shrimp for 30 days at a stocking density of 6000 nos/m3. The heterotrophic bacteria level of 1 × 107 CFU/ml was maintained through three approaches differing in their generation; 1) biofloc lyophilized powder (BFP), 2) biofloc matured water (BFW) and 3) biofloc consortium (BFC) and compared with that of the conventional nursery rearing without biofloc treatment (Control). BFT treatments showed significantly higher growth as observed in average body weight (ABW) (BFP - 0.357 g, BFW - 0.363 g & BFC - 0.391 g) compared to control (0.188 g). BFT groups showed significantly (P < 0.01) higher survival (BFP (81.47%), BFW (79.73%), and BFC (85.4%)), than control groups. The population of heterotrophic bacteria was significantly (P < 0.05) increased in treatments when compared to control. But higher Vibrio load was recorded in the control than BFT water samples. BFT based nursery rearing system improves the water quality parameters when compared to the control. The cumulative mortality rate of biofloc reared juveniles was significantly lowered when challenged with Vibrio whereas, in control, it was higher. Further, certain immune genes like the prophenoloxidase, crustin, MAS, serine protease, alpha-2-M, antiviral genes, and RAN were up-regulated in the BFT groups. All these findings indicate that BFT nursery rearing system gives optimal and better culture condition displaying better survival, growth, disease tolerance, immune activity during the nursery phase and can be managed with minimal water exchange and maximum biosecurity.

Effects of different protein levels and carbon sources on water quality, antioxidant status and performance of common carp (Cyprinus carpio) juveniles raised in biofloc based system

An 8 weeks trial was performed to evaluate the effects of crud protein (CP) levels (20 and 30%) each in three carbon sources in BFT (sugarcane molasses: M, rice bran: R, M + R and control) on water quality and performance of Common carp (cyprinus carpio) juveniles. Seven hundred twenty healthy juveniles (30.5 ± 3.1 g) were randomly distributed in 24 rectangle tanks (200 L) at a density of 4.5 kg m−3 (30 fish/tank). Juveniles in BFT treatments were fed at 75% of the daily feeding rate (DFI) of control. At the end of the experiment, the results showed that among the BFT treatments, M + R in both CP level had the lowest amount of total ammonia nitrogen (TAN) in comparison with other carbon sources in CP levels. The 30% CP level and rice bran contained treatments (R, R + M) significantly increased weight gain, specific growth rate (SGR) and survival and decreased feed conversion ratio (FCR) when compared the M and control treatments (P < 0.01). The highest activity of amylase, total protease and lipase was seen in the higher CP level and R + M treatment which was coincidental with growth performance data in this group. The CP levels did not changed white blood cell (WBC) and packed-cell volume (PCV) but in comparison to low level of CP and control, the 30% CP level and R + M significantly increased red blood cells (RBC) and (hemoglobin test) HB (P < 0.05). Glucose as a stress indicator was not affected by diet CP level however the fish reared in M treatment showed a significant increase in concentration when compared with others (P < 0.01). The higher CP level improved immune response in the fish reared in BFT treatments and the highest concentration for IgM, ACH50, total protein and globulin was seen in R + M treatment which significantly differed from the control (P < 0.05). The similar trend was observed for antioxidant enzymes and the fish fed higher CP level and reared in BFT treatments had significantly better antioxidant status than the control (P < 0.05). According to normal range of CP for Common carp juveniles (35–40%), the results of this experiment suggest that microbial flocs could not compensate 15% reduction of CP in juveniles diets but using R + M as carbon source improves growth performance, immune and antioxidant status in the fish when fed 30% CP.