Nile Tilapia Oreochromis Niloticus Research Articles

Effects of a multi-strain Bacillus probiotic on the intestinal microbiome, haemato-immunology, and growth performance of Nile tilapia.

The study evaluated dietary supplementation with a feed additive composed of multi-strain Bacillus for Nile tilapia Oreochromis niloticus. In vitro and in vivo assays employing culture-based microbiological methods and metagenomics were performed. Additionally, the study assessed the haemato-immunology, intestinal microbiome, and growth performance of the animals. For this, 30 juvenile Nile tilapia were used in the in vitro assay and 180 (60 + 120) in the in vivo assays. In the in vitro assay, we found evidence of adhesion of the probiotic bacteria to the intestinal mucus of fish, corroborated in the 15-day in vivo assay, in which the count of B. licheniformis was significantly higher in fish fed with probiotic when compared to fish of the control group. Furthermore, in the 50-day in vivo trial, a metagenomic analysis provided evidence for the modulation of the intestine microbiome of Nile tilapia by dietary supplementation of the probiotic. In addition, there was an increase in species richness, higher abundance of potentially probiotic autochthonous species and a lower abundance of Aeromonas sp. when the animals were fed the supplemented diet. Finally, no significant differences were observed in growth performance and haemato-immunological analyses, suggesting no harm to fish health when the product was supplemented for 15 and 50 days. The in vitro results indicate that the multi-strain probiotics were able to adhere to the intestinal mucus of Nile tilapia. Additionally, a modulation of the intestinal microbiome was evidenced in the in vivo assay.

Physiological Changes in Nickel-exposed Nile Tilapia Oreochromis niloticus during Exposure and Recovery Periods

Heavy metals are a significant problem in aquatic ecosystems as they are toxic and tend to accumulate, immediately affecting fish physiology. The present investigation was carried out to evaluate the sub-lethality of Nickel chloride on fingerlings of Nile tilapia, Oreochromis niloticus on long-term exposure to it is below safe concentrations1/fifth (9.39 ppm) and 1/10th (4.69 ppm). The physiological studies revealed a significant reduction in Oxygen Consumption Rate (OCR), Ammonia-N Excretion Rate (AER), Oxygen Rate (O: R) and Food Consumption Rate (FCR) and behavioural changes during accumulation and depuration phases. Limited recovery was obtained in all the physiological parameters after depuration for 28 days from the end of the accumulation period.

Anesthetic Efficacy of Lavender and Lemongrass Essential Oils in Nile Tilapia (Oreochromis niloticus, i-Excel strain) Fry

Anesthetics play a crucial role in aquaculture by ensuring the welfare and health of fish, facilitating various procedures, and preventing physical injuries during handling. Recently, plant- based anesthetics for fish are becoming a sustainable alternative to synthetic anesthetics in aquaculture and fisheries research. The present study examined the use of lavender (Lavandula angustifolia) and lemongrass (Cymbopogon citratus) essential oils as anesthetics for Nile tilapia Oreochromis niloticus(i-Excel strain) fry. Fish (average body weight = 0.004 g) were immersed in varying concentrations of 40, 50, 60, 70, and 80 μL L-1 and 30, 40, 50, 60, and 70 μL L-1 for lavender and lemongrass essential oils, respectively. The induction and recovery times were recorded and the best dose was determined based on rapid induction (<3-4 minutes) and quick recovery (<10 minutes). The results indicated that both essential oils exhibit dose-dependent effects on sedation and recovery. Lavender essential oil achieved optimal anesthesia at 60 μL L-1 , with an induction time of 229.3±10.7 seconds and a recovery time of 310.9±16.9 seconds, while lemongrass essential oil induced optimal anesthesia at 30 μL L-1 , with an induction time of 232.5±11.7 seconds and a recovery time of 130.5±8.6 seconds. Both concentrations for both essential oils resulted in 100.0% survival, while higher doses induced faster anesthesia and recovery but decreased survival rates. These essential oils offer cost-effective alternatives to synthetic anesthetics for short-term handling procedures; however, further research on histopathological effects and optimal transport dosages is needed.

Partial substitution of fish meal by biofloc meal in diets for Nile tilapia Oreochromis niloticus

The effect of a partial substitute of fish meal by biofloc meal on the growth and survival of fry Nile tilapia Oreochromis niloticus was evaluated over nine weeks. Two biofloc meals were obtained by drying them in two processes: A) sun exposure and B) convection oven. A randomized design of eight isonitrogenous (40%) and isoenergetic (17 kJ g-1) diets was used, where 5, 10, 15, and 20% of the fish meal was substituted for the two biofloc meals. The nutritional study was conducted in a recirculating aquaculture system with Nile tilapia fry (initial weight: 0.64 ± 0.16 g). The survival range was similar in all treatments and higher than 97%. Tilapia fed with the treatments A5, A10, B5, and B10 of substitution of biofloc meal showed similar and significantly better final weight, individual weight gain, specific growth rate, and condition factor than A15, A20, B15, and B20 treatments; as well as efficiency of use of the feed: protein efficiency ratio, carcass nitrogen deposition, apparent nitrogen utilization, and apparent digestibility. Therefore, these results suggest that biofloc meal is possible in diets for tilapia, thus reducing the need for fishmeal as the main source of protein in the diet.

Effects of supplementation with different zinc-based products on the growth and health of Nile tilapia

Zinc is one of the essential microelements for the metabolism of animals. Zinc nanoparticles may have higher bioavailability due to their low specific surface area, facilitating absorption by fish. The present study aimed to evaluate the effects of supplementation with different zinc-based products on the growth and health of Nile tilapia Oreochromis niloticus. Zinc, in different sizes (nanoparticles or bulk) and forms (inorganic or organic), were used as a supplement in the tilapia diet at a dose of 15 mg kg feed−1 for 60 days. At the end of the feeding trial, production performance, hemato-immunological parameters, activity of antioxidant system enzymes, exposure to Streptococcus agalactiae and zinc concentration in the muscle were examined. After the bacterial challenge, the mean corpuscular hemoglobin concentration (MCHC) significantly increased in the fish treated with organic zinc, inorganic nano zinc, and organic nano zinc, while in the control group (inorganic zinc), MCHC remained unchanged. Regarding defense cells, dietary inorganic nano zinc increased the number of basophils (1.50 ± 1.10) compared to organic zinc (0.80 ± 0.90). Lymphocyte count increased after the challenge only in the organic zinc treatments (bulk and nanoparticles). Neutrophils decreased in the control (inorganic zinc) (2.20 ± 1.70) and inorganic nano zinc (2.60 ± 2.70) treatments after the challenge. When compared before and after the bacterial challenge, the plasma antimicrobial titer significantly increased after the bacterial challenge in all treatments. No significant differences were observed for total proteins, enzymes (SOD and CAT), cumulative survival and zinc deposition on fillet. In conclusion, organic zinc in nanoparticles or bulk size increased Nile tilapia innate defense during bacterial infection. However, the other parameters evaluated were not affected by zinc particle size or form (organic or inorganic), indicating that further evaluations should be conducted with organic zinc in nanoparticles or bulk size in the tilapia diet.

Biofilm viability and microbial community of non-inoculated moving bed biofilm reactor in Nile tilapia Oreochromis niloticus cultivation

The aim of this study was to evaluate two moving bed biofilm reactors (MBBR) without nitrifying bacteria inoculation. Biofilms and viable bacterial colonies were evaluated after 124 days. MBBR bioreactors received water from Oreochromis niloticus fish farming and water quality parameters were monitored daily. Four distinct phases with different fish stocking density were established.: phase 1 (2.40 kg m−3), phase 2 (4.95 kg m−3), phase 3 (8.71 kg m−3) and phase 4 (12.23 kg m−3). The successful maturation of the bioreactors occurred around on the 100th experimental day when the nitration rate increased to 57 % in MBBR1 and 38 % in MBBR2. 105 species were identified in the biofilms, which were grouped into 65 genera, three of which were essential: Pseudomonas (21.7 %), Nitrospira (15.1 %) and Gemmobacter (11.2 %). MBBR start-up without bacterial inoculation is time-consuming, however, strengthened by important nitrifying groups.

Valorization of two sources of maggots in the diet of Nile tilapia Oreochromis niloticus

Valorization of two sources of maggots in the diet of Nile tilapia Oreochromis niloticus

Expression profiles of four Nile Tilapia innate immune genes during early stages of Aeromonas veronii infection.

During Egypt's hot summer season, Aeromonas veronii infection causes catastrophic mortality on Nile Tilapia Oreochromis niloticus farms. Egypt is ranked first in aquaculture production in Africa, sixth in aquaculture production worldwide, and third in global tilapia production. This study aimed to investigate, at the molecular level, the early innate immune responses of Nile Tilapia to experimental A. veronii infection. The relative gene expression, co-expression clustering, and correlation of four selected immune genes were studied by quantitative real-time polymerase chain reaction in four organs (spleen, liver, gills, and intestine) for up to 72 h after a waterborne A. veronii challenge. The four genes studied were nucleotide-binding oligomerization domain 1 (NOD1), lipopolysaccharide-binding protein (LBP), natural killer-lysin (NKL), and interleukin-1 beta (IL-1β). The four genes showed significant transcriptional upregulation in response to infection. At 72 h postchallenge, the highest NOD1 and IL-1β expression levels were recorded in the spleen, whereas the highest LBP and NKL expression levels were found in the gills. Pairwise distances of the data points and the hierarchical relationship showed that NOD1 clustered with IL-1β, whereas LBP clustered with NKL; both genes within each cluster showed a significant positive expression correlation. Tissue clustering indicated that the responses of only the gill and intestine exhibited a significant positive correlation. The results suggest that NOD1, LBP, NKL, and IL-1β genes play pivotal roles in the early innate immune response of Nile Tilapia to A. veronii infection, and the postinfection expression profile trends of these genes imply tissue-/organ-specific responses and synchronized co-regulation.

Effect of Dietary Seaweed Supplementation on Growth, Feed Utilization, Digestibility Co-efficient, Digestive Enzyme Activity and Challenge Study against Aeromonas hydrophila of Nile Tilapia Oreochromis niloticus

Background: The present study aimed to determine the growth, digestibility co-efficient, digestive enzyme activity and disease resistance of juvenile GIFT tilapia fed with Ulva seaweed meal supplemented diet. Methods: The study was undertaken with different inclusion levels of Ulva seaweed meal (USM) such as raw (UR) and fermented (UF) Ulva meal (UR-5, UR-10, UR-15, UF-5, UF-10 and UF-15% of diet) and control feed (C) for a period of 60 days. Result: GIFT fed with fermented Ulva meal at a 10% inclusion level in their diet exhibited the highest growth performance (41.43 g) followed by UF5 (41.07±0.43 g), UR5 (39.65±0.36 g), control (39.09±0.20 g), UF15 (38.67±0.26 g), UR10 (38.47±1.47 g) and UR15 (35.77±0.35 g) diet. The Highest Apparent Digestibility Coefficient (ADC) for Crude Protein (85.14±0.91%) was observed in fishes fed with fermented Ulva meal at a 10% inclusion rate than other treatments and the control groups for Dry Matter, Ether Extract, and Gross Energy. The enzymatic activities of digestive enzymes, namely Amylase activity (0.029±0.00 units/mg protein/min), Protease activity (0.147±0.0 units/mgprotein/min) and Lipase activity (0.273±0.05 units/mg protein/min), showed higher levels in the group of fishes fed with a diet containing 10% fermented Ulva meal, as compared to the other treatment groups and the control. Increased survival rate (86.66%) was observed when the fishes were challenged with Aeromonas hydrophila at the end of the trial for Ulva based diets. The results obtained on histopathology showed the presence of lower degree levels of infection in 10% fermented Ulva meal supplementation.The present study concluded that dietary Ulva meal requirement for juvenile GIFT tilapia can be at 10% of Ulva Fermented (UF) and UF-5, Ulva Raw (UR) 5%, control (C), UF-15, UR-10 and UR-15 diet respectively.

Protozoan and helminths infestation of Nile tilapia Oreochromis niloticus and its correlation with certain water quality variables along river Nile in the area of Greater Cairo

Pollutants and parasites represent stressors for fish at the individual, population, or community levels. The current study outlines the seasonal infestation pattern of Oreochromis niloticus by protozoan and helminths parasites linked to some physicochemical parameters (pH, dissolved oxygen, total dissolved solids, and electrical conductivity), and metals (Cd, Pb, Fe, Zn, and Ca), at nine selected sites in River Nile (Greater Cairo area) from summer 2019 till spring 2020. Most of the studied criteria in Nile water samples showed normal levels during all seasons compared to the recommended limits of EPA. The parasitological examinations recorded three protozoan categories: Myxobolus (8 species), hemoflagellates (Trypanosoma mukasi) and Ciliates (Trichodina compacta), and three helminths; Clinostomum sp., Acanthocephala sp. and Euclinostomum ardeola. The highest incidence of infection was determined for Clinostomum sp., followed in descending order by Myxobolus sp., Acanthocephala sp., T. mukasi, E. ardeolathen, and T. compacta. Notably, this study introduces the novel identification of new species of Myxobolus in the blood of Oreochromis niloticus. The histopathological examination of gills, muscles, and kidneys reveals serious changes and the presence of encysted trematodes, metacercariae, and cysts of protozoan parasites. Additionally, the study employs cluster analysis based on site similarity in water variables and canonical correspondence analysis, explaining 98.7 % of the variables and indicating correlations between parasite infestation and environmental factors. These analytical approaches reveal the impact of land use activities on water variables and the influence of adjacent activities on fish parasite infestation patterns. In conclusion, this study provides a comprehensive perspective by considering various factors to enhance our understanding of pollutants and parasites affecting fish in the River Nile.

Digestibility of corn distiller's dried grains with solubles (DDGS) in practical feeds with phytase and xylanase treatment fed to Nile Tilapia

AbstractObjectiveDistiller's dried grains with solubles (DDGS), a by‐product of ethanol production from cereal grains, has seen limited use by fish feed manufacturers as an alternative protein source. Over the past 20 years, advances and greater uniformity in processing methods have improved the quality of DDGS and, likely, its digestibility by fish. Our objective was to reevaluate the digestibility of corn DDGS by Nile Tilapia Oreochromis niloticus using a present‐day commercial product with and without xylanase and phytase enzyme treatment.MethodsApparent digestibility coefficients (ADCs) for the major proximate nutrients (dry matter, crude protein, crude fat, ash, digestible energy, and phosphorus) were determined using a practical, commercial‐type feed that was formulated and processed with DDGS supplied at 30% as weight : weight substitution (DDGS diet) of the reference diet (Ref diet). After drying, Ref and DDGS diets were top‐coated with phytase (3310 FTU/kg) + xylanase (7665 BXU/kg) enzymes (Ref+ and DDGS+) and compared with their untreated dietary counterparts.ResultDigestibility of crude protein was similar among diets and unaffected by enzyme treatment. For dry matter and digestible energy, ADC values were significantly lower for the DDGS diet, but enzyme addition improved digestibility to that of the Ref diets. Apparent digestibility for crude fat and ash was significantly better for the DDGS feed, with ash digestibility improved after treatment with xylanase + phytase for both Ref+ and DDGS+. For phosphorus, digestibility was similar among the Ref, Ref+, and DDGS diets, but with enzyme treatment, the phosphorus ADC increased significantly in DDGS+.ConclusionResults of this digestibility trial show that corn DDGS is a highly digestible protein source for use in feeds of Nile Tilapia at 30% of diet. Generally, apparent digestibility of proximate nutrients was either better or similar in DDGS when compared with the reference diet and could be further improved with the addition of xylanase + phytase.

Effect of aeration systems under desert conditions on growth, survival and yield of Nile tilapia Oreochromis niloticus

Effect of aeration systems under desert conditions on growth, survival and yield of Nile tilapia Oreochromis niloticus

Feed efficiency, hematological parameters, and resistance against Streptococcus agalactiae of Nile tilapia (Oreochromis niloticus) as improved by dietary supplementation of Lactobacillus plantarum L03

ABSTRACTThe utilization of beneficial bacteria in aquaculture is increasingly advocated due to their positive impact on fish growth and health. This study assesses the effect of dietary Lactobacillus plantarum L03 on the growth and disease resistance of Nile tilapia Oreochromis niloticus. Fish (19.07 ± 0.43 g) were fed with a diet supplemented with L. plantarum at 0, 2, 5, 10 g/kg (referred to as LP0, LP2, LP5, and LP10 treatments) for seven weeks. One day after the end of experiment, fish were infected with Streptococcus algalactiae at 5 × 105 CFU/mL and monitored for 14 days. Blood samples were collected for hematological analyses after feeding trial and bacterial challenge. The results indicated no effects of dietary L. plantarum on fish growth, while the positive effects on feed conversion ratio and protein efficiency ratio (P < .05) were found in LP2 and LP5-fed fish. The supplementation of probiotics exhibited beneficial effects on red and white blood cells, hemoglobin, hematocrit, and mortality after bacterial challenge for LP5 treatment (P < .05). In conclusion, LP5 treatment at a dietary supplementation of 5 g L. plantarum per kg resulted in positive outcomes on feed utilization, cellular immunity, and disease resistance in Nile tilapia.

Assessment of hydrolysis of partially defatted black soldier fly larvae meal in diets for Nile tilapia Oreochromis niloticus

The chitin content of black soldier fly (Hermetia illucens) larvae meal (BSFM) is known to negatively affect its digestibility by fish. Nile tilapia (Oreochromis niloticus) tolerates well BSFM in the diet. However, chemical hydrolysis of dietary BSFM has not previously been attempted for this species. In this study, based upon a low-fishmeal control diet (40% crude protein and 9% crude fat), three levels of dietary protein, 25%, 50%, and 75%, were replaced by partially defatted BSFM, subjected or not to a prior hydrolysis treatment with formic acid and fed to Nile tilapia juveniles (initial body weight: 0.26 ± 0.00 g). The hydrolysis treatment did not modify greatly the proximate and amino acid composition of the diets, nor did it improve their in vivo apparent digestibility coefficients of dry matter or crude protein. However, it significantly increased the contents of arginine, taurine, and tyrosine, and significantly reduced the contents of methionine, valine, aspartic acid, and glutamic acid in muscle tissue of Nile tilapia. The hydrolysis treatment also decreased fish growth significantly. In contrast, for diets not containing hydrolyzed BSFM, not only did fish fed all three levels of protein replacement grow satisfactorily, but the diets with the levels of replacement of 50% and 75%, with final weights of 23.04 and 23.11 g, respectively, elicited superior fish performance, as compared to the diet with 25% replacement (final weight of 20.09 g). In addition, all three protein replacement diets produced significantly greater growth than the control diet (final weight of 17.72 g). The actual levels of inclusion of BSFM were, respectively, 14.11%, 28.21% and 42.33% of diet, the latter being the highest inclusion level of BSFM reported to date for successful growth of Nile Tilapia.

Metal-amino acid complexes (Zn, Se, Cu, Fe, and Mn) enhance immune response, antioxidant capacity, liver function enzymes, and expression of cytokine genes in Nile Tilapia reared under field conditions.

In the present study, we investigated the effects of partial or total replacement of dietary inorganic trace materials (ITM) with metal-amino acid complexes (MAACs) on immune response, antioxidant capacity, cytokine genes expression, and overall health status of Nile Tilapia Oreochromis niloticus reared in in-pond hapas (mesh cages) under field conditions. All-male Nile Tilapia with an average initial weight of about 90 g fish-1 were stocked into the hapas, in quadruplicates, at a density of 60 fish per hapa (30 fish m-3 ). The fish in each hapa were acclimatized to culture conditions and test diets for 1 week. Water quality parameters, including temperature (°C), pH, dissolved oxygen (mg L-1 ), and total ammonia (mg L-1 ), were monitored regularly. The MAACs were formulated to contain the same mineral concentrations found in the inorganic premix. Metal-amino acid complexes replaced the ITM premix at 0 (control), 25, 50, 75, and 100% levels (Table 1). The diets were fed to caged Nile Tilapia twice a day, for 80 days, at a daily rate of 3% of their body weights. The fish were weighed every 10 days, and the daily rations were readjusted. At harvest, fish in each hapa were collected, counted, and weighed collectively. Five fish from each hapa were rapidly anesthetized, and used for chemical and physiological analyses, including antioxidant and immune response analyses, liver function analysis, and gene expression. The activities of lysozyme, respiratory burst (%), alternative complement (ACH50), phagocytic cells, phenoloxidase, superoxide dismutase, glutathione peroxidase, and liver function enzymes were all improved with increasing supplemental MAACs up to the 50% substitution level. The expression of cytokine genes, including interferon, tumor necrosis factor, interleukin-1, serum alkaline phosphatase, the integrated microbial genomes, chloramphenicol acetyltransferase, and transforming growth factor genes, was significantly upregulated in fish fed on MAAC-supplemented diets compared with the control group. The 50% MAAC level produced the highest upregulation of these genes, whereas gene expression decreased with increasing dietary MAAC levels to 75% and 100%. The quadratic regression analysis indicated that about 60-65% MAAC is required for maximum promotion of immunological and oxidative stress responses, gene expression, and overall health status of Nile Tilapia reared in in-pond hapas under field conditions. Replacement of the ITM premix with a MAAC premix enhanced the immune and antioxidant responses of Nile Tilapia.

Dietary Cholesterol and Aggression in Nile tilapia Oreochromis niloticus

AbstractTilapia farmers would benefit tremendously if they could decrease aggression among fish. Conspecific aggression affects growth, feed conversion and general wellbeing of fish. Previous studies established an inverse relationship between blood cholesterol levels and aggression in fish, whereby a decrease in cholesterol led to an increase in aggression. The present study assessed the effect of an increase of dietary cholesterol on blood cholesterol and possible decrease in aggression of Nile tilapia Oreochromis niloticus. Nile tilapia were stocked in an outdoor recirculation system then offered one of five diets: 0% cholesterol, 0.5% cholesterol, 1% cholesterol, 1.5% cholesterol and 2% cholesterol. Five fish of each treatment were moved to a glass tank and monitored for signs of aggression for 10 minutes, twice a day. This experimental procedure was repeated five times using a new set of fish every time. Results show an increase in cholesterol levels in the blood but that there are no significant differences in aggression among treatments. Accordingly, the present study suggests that an increase in dietary cholesterol increases blood cholesterol in fish but does not have a significant effect on antagonistic patterns in Nile tilapia.This article is protected by copyright. All rights reserved.

Efficacy of Oxolinic Acid Against Aeromonas hydrophila Infection in Nile tilapia Oreochromis niloticus Juveniles

Oxolinic acid (OA), a broad-spectrum quinolone antibiotic that plays a crucial role in human medicine, is often used in aquaculture as a second-line treatment at 12 mg/kg biomass/day continuously for seven days. The objective of this study was to assess its effectiveness against Aeromonas hydrophila infection in Nile tilapia Oreochromis niloticus in terms of progression and healing of wounds, clinical biochemistry and histopathological changes upon challenge and treatment. To evaluate the efficacy, the juveniles were intramuscularly challenged with A. hydrophila at a sublethal dose of 1.93×106 cells/fish, followed by the administration of OA-supplemented feed at 2% body weight daily for seven days. OA treatment yielded better consequences in terms of increased feed intake and biomass and decreased plasma biochemical parameters, histopathological changes and improved recovery from A. hydrophila infection compared to the untreated group. Wounds of the OA-treated group healed at a faster rate, with complete healing within 12 days post-injection, while the wounds of the untreated group took longer to heal. Though the efficacy of OA against A. hydrophila infection in tilapia was established in this study, it is important to exercise caution regarding its application in aquaculture due to its classification as a critically important medicine for humans.

Sustainable Production of Tomato Using Fish Effluents Improved Plant Growth, Yield Components, and Yield in Northern Senegal

Aquaculture and agriculture integration is essential for maximizing water and land productivity in arid and semi-arid regions. Thus, the increase in global water scarcity and the dual use of water for crop and fish production has the potential to optimize water use, dispose of aquaculture wastes, provide additional nutrients to crops, and reduce inorganic fertilizer usage, thus maximizing farm productivity. This greenhouse study was conducted to determine the effects of fish effluents on the growth, yield parameters, and yield of tomatoes (Solanum lycopersicum L.). The experiment was carried out in a randomized complete block design with six replications. The 13 treatments consisted of three irrigation water types (river water—control, Nile tilapia—Oreochromis niloticus, African sharptooth catfish—Clarias gariepinus), four fertilizers (chicken manure, cow manure, sheep manure; recommended rate of NPK—280 kg ha−1 of 10-10-20), and six mixed treatments with fish effluent and 50% of the applied rate of manure alone. Results showed that irrigation with C. gariepinus effluent increased the stem diameter by 21%, the number of flowers by 88%, the fruit number by 50%, the fruit diameter by 24%, the mean fruit weight by 34%, and total fruit weight of tomato by 96% compared to NPK treatments. These effects were more evident when C. gariepinus was mixed with poultry, cow, and sheep manures, which resulted in significantly greater values than recommended rates of NPK. The higher productivity observed from the combined use of C. gariepinus and manure treatments (133% increase, on average) compared to NPK treatments was related to the continuous supply of nutrients and the increase of yield parameters. Therefore, the combined use of C. gariepinus effluent and manure can be a viable alternative for smallholder farmers, for whom inorganic fertilizers are often neither affordable nor available.

Widespread occurrence of Tilapia parvovirus in farmed Nile tilapia Oreochromis niloticus from India.

Tilapia parvovirus (TiPV) has been associated with heavy mortalities in tilapia as a single infection or in co-infection with Tilapia lake virus (TiLV). In this study, TiPV was detected in farmed Nile tilapia, Oreochromis niloticus, from two geographical regions of India, Maharashtra and Uttar Pradesh. TiPV-specific polymerase chain reaction (PCR) reported earlier was used in the screening. Tilapia collected from Maharashtra showed characteristic clinical signs, and TiPV was detected along with TiLV and/or Aeromonas spp. However, fish from Uttar Pradesh were apparently healthy and only TiPV could be detected in these samples. A high prevalence of TiPV was recorded from both the geographical locations, Maharashtra and Uttar Pradesh (59.6% and 95.0% respectively). The virus could be detected in tissues such as the spleen, liver, kidney, brain and mucus. The spleen appeared to be the best tissue for detecting TiPV in apparently healthy tilapia. The presence of TiPV was further confirmed through sequencing the PCR products, isolation of the virus in the cell line and electron microscopy. Sequences of the NS1 gene of the two TiPV isolates showed similarity to the earlier reported TiPV isolates. The virus could be successfully propagated in O. niloticus Liver (OnL) cell line, and cytopathic effect was observed as early as 3 days post-infection. Furthermore, the presence of non-enveloped icosahedral to round virus particles measuring about 26-35 nm could be demonstrated in the cytoplasm and nucleus of infected OnL cells in transmission electron microscopy. With this confirmation of the presence of the virus, India is the third country to report TiPV after China and Thailand. The detection of TiPV in co-infection cases with TiLV and in apparently healthy Nile tilapia suggests its wide distribution and potential synergistic effect in co-infection cases. Therefore, this emerging virus needs holistic attention to understand its virulence, host-specificity and epidemiological risk factors.

Evaluation of fermented soybean meal by Bacillus subtilis as an alternative to fishmeal on the growth, and physiological status of Nile tilapia Oreochromis niloticus fingerlings

A feeding trial was conducted to investigate the effect of fermented soybean meal with Bacillus subtilis bacteria on growth performance, feed utilization, carcass composition, and hematological, and histological section of the liver and intestine of Nile tilapia Oreochromis niloticus fingerlings. Commercial soybean meal (SBM) containing 44% Crude Protein (CP) was fermented using the solid-state fermentation method which depended on autoclaving of SBM, then bacterial treatment injection by Bacillus subtilis, and finally incubation at 40C for 72 h then autoclaved to stop the growth of bacteria. Five isonitrogenous (25% crude protein) and isocaloric (4.4 kcal\\g gross energy) experimental fish meal-free diets were formulated to compare with a common control diet containing fishmeal and unfermented soybean meal. Diets without fish meal contain fermented soybean meal (FSM) as a sole protein, FSM with corn gluten (CG), FSM with free amino acid methionine (Meth), FSM with corn gluten and methionine, and unfermented soybean meal. Eighteen glass aquaria, 80-L net volume, were used to stock 10 fingerlings (10.0 ± 0.1 g/fish) in each aquarium in the replicates group. The feed amount was given three times daily, six days a week throughout the 98 days experimental period. Fish were weighed biweekly and feed amounts were adjusted based on the new fish weight. Bacterial fermentation enhanced the protein content of commercial soybean meals by 6%. The crude protein of fermented soybean meal increased from 43.44% to 50.67%. Used of FSM as a sole dietary protein source resulted in a decrease in growth rate and feed utilization. However, the incorporation of FSM with corn gluten, and/or methionine amino acid led to an improvement in the performance of fish. Finally, the best final body weight, weight gain, specific growth rate, protein efficiency ratio, and protein productive value were recorded by a fish-fed mixed plant protein diet (FSM + CG + Meth). Also, Hematocrit and red blood cells were not significantly affected including the FSM.