Browsing by Author "Oladosu G. A."

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A gross and light microscopic study of three Neoplasms in farmed Clarias gariepinus and its hybrid
(African Union - Interafrican Bureau for Animal Resources (AU-IBAR), 2017) Tijani M. O.; Oladosu G. A.
There are only a few reports of neoplasms and associated pathologies in teleosts. Three different tumours observed in three different fishes were examined grossly and histologically. In the first C.gariepinus, a large irregular, bristly, pinkish mass was observed to be protruding from the oral cavity. Histopathology of the mass revealed numerous denticles and an abundant fibrovascular stroma. Histopathologically, the tumour was diagnosed as a compound odontoma. In the second C. gariepinus, numerous pale yellow to whitish nodules were observed in the liver. Histopathology of the tumours revealed numerous atypical hepatocytes growing in thick trabeculae within nodules compressing adjacent normal hepatocytes. Individual hepatocytes were pleomorphic, large and vacuolated. The cytoplasmic vacuoles frequently contained globular hyaline bodies. These findings prompted a diagnosis of hepatocellular carcinoma. The ovaries of the female hybrid-Clarias gariepinus x Heterobranchus. Longifilis, were observed to be severely distorted by numerous whitish, irregular, nodules. Histopathologically, the tumour revealed sheets and nests of oval to round cells split into lobules by a fibrous stroma. Each cell possessed scanty to moderately abundant eosinophilic to amphophilic cytoplasm, hyperchromatic round to oval central nucleus with coarse chromatin and multiple nucleoli. Mitotic figures were frequently observed. The tumour was presumptively diagnosed as a dysgerminoma. The aetiologies of these tumours were not determined.
Aetiology, epizotiology and pathology of ‘rusty yellow’ skin discolouration of tilapia species Oreochromis niloticus and Tilapia zilli
(Blackwell Wissenschafts-Verlag, 1994) Oladosu G. A.; Ayinla, A,; Ajiboye, M. O.
The presence of a rusty-yellow discolouration of the skin of the two tilapia species being cultured at the African Regional Aquaculture Centre (ARAC) was studied using clinical and epizootiological methods. The condition affected the tilapia species only. Ante-mortem and post-mortem examination revealed that the discolouration was restricted to the surface of the cutaneous tissue; affecting the underside of the exposed part of the scales, the fins, and the skin flap covering the scale pockets, mostly in adult fish. Microbiological and histopathological studies, as well as experimental infection trials demonstrated that a rosette-shaped, filamentous gram-positive bacterium, was the aetiologic agent. This organism was characterised as an Actinomyces species based on standard microbiological techniques. Correlation between physico-chemical parameters of the pond water and the prevalence of the skin discolouration, suggested a possible relationship to low dissolved oxygen. The prevalence of the skin discolouration was observed to increase over the 4-month culture period, being somewhat greater in a non-integrated than in an integrated culture system at harvest. Efforts to control the condition with available chemotherapeutics (mostly disinfectants and antibiotics) were ineffective although the organ- ism was observed to be sensitive to terramycin.
An assessment of the pathogenicity of Edwardsiella tarda and treatment of experimental edwardsiellosis in cutured Clarias gariepinus (Cuvier 1822)
(Fisheries and. Aquatic Science, 2016) Oladosu G. A.; Olufemi B. E.; Ighara O.
The pathogenicity of Edwardsiella tarda isolated from pond water, and chemotherapeutic control of experimental edwardsiellosis in cultured Clarias gariepinus were investigated. The E. tarda isolate was identified based on colony and cellular morphology, as well as biochemical characteristics. A total of 120 fish were randomly assigned to four groups (A, B, C and D) of 30 fish, each comprising of 15 fish replicated once. Fish in groups A, B and C were infected intra-peritoneally with 1.02x10 cfu of E tarda, while group D was not infected. Following observation of clinical signs, group A was treated with ciprofloxacin by 1hour immersion at 25mg/litre of water and group B orally at 100mg/kg body weight of fish for five days. Fish in group (C) were not treated with ciprofloxacin. Fish were observed for mortality daily, and cumulative mortality was compared between groups using ANOVA and Duncan Multiple Range Test. Cumulative mortality of 56.66% observed in group C was significantly higher (p < 0.05) than in groups A and B treated via oral (3.33%) and immersion (3.33%) route respectively. Infected fish were effectively treated by both routes of ciprofloxacin application, but the oral route is considered less stressful for the sick fish.
Antibiotic sensitivity and sodium chloride susceptibility patterns of Flavobacterium columnare isolated from clinical columnaris in cultured Clarias gariepinus
(Academic Journals, 2019) Oladosu G. A.; Oladosu O. O.
Antimicrobial resistance is a global concern, especially with the backdrop of the development of possible environmental and public health hazards. Flavobacterium columnare has been observed to be multi-drug resistant but highly susceptible to sodium chloride, hence the need for susceptibility profiling. Therapeutic efficacy of commonly used antibiotics and sodium chloride was tested in-vitro against four isolates of F. columnare using the disc diffusion and the pour plate methods, respectively. Comparative in-vivo testing was performed on experimentally infected Clarias gariepinus juveniles in 11 groups of 15 fish each. Nine groups were treated with 1.0, 2.0 and 3.0% NaCl for 5, 10 and 30 min each. A tenth group was exposed to 25 mg L ciprofloxacin for 1 h by immersion, while the eleventh group was not treated (positive control). Growth inhibition was observed to be highest with ciprofloxacin followed by ofloxacin and tetracycline in that order, and also in all NaCl concentrations. There was no mortality in the infected fish groups treated with 25 mg L" ciprofloxacin, 1% NaCl, and 2 to 3% NaCl for 5 and 10 min only. However, 46.7 ± 9.4 % mortality observed in 3 % NaCl treatment for 30 min was significantly higher than the 23.3 ± 4.6% observed in 2 % NaCl for 30 min, but not significantly different from the positive control with 36.7±4.7 % mortality. Since short duration sodium chloride bath was found to be effective in the control of columnaris disease, 1% salt disinfection of fry and fingerling stock for 30 min could be incorporated into routine management in catfish hatchery, without the fear of environmental or public health hazards.
Aquaculture practice in management of fish disease and biosecurity
(Department of Aquaculture and Fisheries Management, University of Ibadan, Nigeria., 2015) Akinwole A. O.; Oladosu G. A.; Ajani E. K.
Arborescent organ necrosis syndrome in catfish, Clarias gariepinus (Burchell): A case report
(Blackwell Publishing LTD, 2011) Oladele O. O.; Olufemi B. E.; Oladosu G. A.; Ajayi O. L.; Adediji, A. A.; Arasi I. O.
Bacterial contamination of stored table eggs from commercial chickens fed garlic meal additives
(African Union - Interafrican Bureau for Animal Resources (AU-IBAR), 2017) Oladele O. A.; Oladosu G. A.; Esan O. O.; Ahankonye I. C.
"Table eggs from poultry farms sometimes take weeks before consumption during which period they are either in-transit to consumers or are stored until purchased. Microbial contamination during this period being the cause of spoilage, determines the shelf-life of eggs. Garlic is known to possess antimicrobial activities. Its potential at improving the shelf-life of table eggs was investigated. Three hundred and fifty-one Isa Brown pullets separated into four groups A, B, C and D of 90,81, 90 and 90 birds, were placed on garlic-meal feed additive at 0.125%, 0.25%, 0.5% and 0%, respectively. At 53 week-old, sixty eggs/group were kept at room temperature (26-27.50C), from which 8 eggs/group were selected on the day of lay and weekly for 4 weeks. One ml of vortex mixed albumin and yolk pooled from 4 eggs was diluted 1:10, inoculated on Plate Count Agar-PCA, Salmonella-Shigella Agar-SSA, Eosin-Methylene Blue Agar-EMBA and Saborand Dextrose Agar-SDA by pour plate method in duplicates and incubated at 360C for 72 hours. Discrete colonies were sub-cultured in Nutrient agar and identified using cellular morphology and biochemical characteristics. Bacterial growths were observed in groups A, C and D (75,0 and 0 cfu/ml in EMBA, 100, 125 and 225 cfu/ml in PCA and 0,25 and 25 cfu/ml in SSA, respectively, at 2 weeks of storage.At 3 weeks, all groups had bacterial growth except B, while at 4 weeks, all groups had bacterial growth with B having a load of 25.5 cfu/ml on PCA only. Escherichia coli, Enterobacter cloacae, Klebsiella pneumonia, Stenocrophomonas maltophilia and Citrobacter amalonaticus were isolated. Garlic-meal in feed of chicken layers at 0.25% delayed bacterial egg contamination, thereby prolonging the shelf-life and reducing the possibility of food poisoning in consumers, as well as, egg wastage with associated economic loss."
Bioprophylaxis of Saprolegniasis in Incubated Clarias gariepinus Eggs Using Pyocyanin Extracted from Pseudomonas aeruginosa
(World Academy of Science, Engineering and Technology, 2022) Oladosu G. A.; Ogbodogbo P. O.; Makinde C. I.; Tijani M. O.; Adegboyega O. A.
Saprolegniasis is a major pathogenic infection that contributes significantly to poor hatching rates in incubated fish eggs in the African catfish hatchery in Nigeria. Malachite green, known to be very effective against this condition, has been banned because it is carcinogenic. There is therefore the need for other effective, yet safer method of controlling saprolegniasis in incubated fish eggs. A total of 50 ml crude, chloroform extract of pyocyanin from which solvent was removed to attain 30 ml, having a concentration of 12.16 ug/ml was produced from 700 ml broth culture of Pseudomonas aeruginosa isolated from a previous study. In vitro susceptibility of the fungus was investigated by exposing fungal infected eggs to two different time-concentration ratios of pyocyanin; 0.275 ug/ml and 2.75 ug/ml for 1 and 24 h, and 5 mg/L malachite green as positive control while normal saline was the control. Efficacy of pyocyanin was evaluated using the degree of mycelial growth inhibition in the different treatments. Fertilized Clarias gariepinus eggs (between 45 to 64 eggs) were then incubated in 20 ml of medium containing the similar concentrations of pyocyanin and malachite green, with freshwater as control for 24 hours. Hatching rates of the incubated eggs were observed. Three samples of un-hatched eggs were taken from each medium and observed for the presence of fungal pathogens using microscopy. Another batch of three samples of un-hatched eggs from each treatment was also inoculated on Sabourand dextrose agar (SDA) using Egg-Agar Transfer technique to observe for fungal growth. Mycelial growth was inhibited in fungal infected eggs treated with 2.75 ug/ml for 24 h and the 5 mg/L malachite green for both 1 h and 24 h. The mortality rate was 100% in fertilized C. gariepinus eggs exposed for 24 h to 0.275 and 2.75 ug/ml of pyocyanin. The mortality rate was least in the malachite green followed by the control treatment. Embryonic development was observed to be arrested in the eggs treated with the two pyocyanin concentrations as they maintain their color but showed no development beyond the gastrula stage, whereas viable eggs in the control and malachite green treatments developed fully into healthy hatchlings. Furthermore, microscopy of the un-hatched eggs revealed the presence of a protozoan ciliate; Colpidium sp. (Tetrahymenidae), as well as a pathogenic fungus; Saprolegnia sp. in the control, but not in the malachite green and pyocyanin treatments. Growth of Saprolegnia sp. was also observed in SDA culture of un-hatched eggs from the control, but not from pyocyanin and malachite green treated eggs. Pyocyanin treatment of incubated eggs of Clarias gariepinus effectively prevented fungal infection in the eggs, but also arrested the development of the embryo. Therefore, crude chloroform extract of pyocyanin from Pseudomonas aeruginosa cannot be used in the control of Saprolegniasis in incubated Clarias gariepinus eggs at the concentration and duration tested in this study.
Bioprophylaxis of Saprolegniasis in Incubated Clarias gariepinus Eggs Using Pyocyanin Extracted from Pseudomonas aeruginosa
(World Academy of Science, Engineering and Technology, 2022) Oladosu G. A.; Ogbodogbo P. O.; Makinde C. I.; Tijani M. O.; Adegboyega O. A.
Saprolegniasis is a major pathogenic infection that contributes significantly to poor hatching rates in incubated fish eggs in the African catfish hatchery in Nigeria. Malachite green, known to be very effective against this condition, has been banned because it is carcinogenic. There is therefore the need for other effective, yet safer method of controlling saprolegniasis in incubated fish eggs. A total of 50 ml crude, chloroform extract of pyocyanin from which solvent was removed to attain 30 ml, having a concentration of 12.16 ug/ml was produced from 700 ml broth culture of Pseudomonas aeruginosa isolated from a previous study. In vitro susceptibility of the fungus was investigated by exposing fungal infected eggs to two different time-concentration ratios of pyocyanin; 0.275 ug/ml and 2.75 ug/ml for 1 and 24 h, and 5 mg/L malachite green as positive control while normal saline was the control. Efficacy of pyocyanin was evaluated using the degree of mycelial growth inhibition in the different treatments. Fertilized Clarias gariepinus eggs (between 45 to 64 eggs) were then incubated in 20 ml of medium containing the similar concentrations of pyocyanin and malachite green, with freshwater as control for 24 hours. Hatching rates of the incubated eggs were observed. Three samples of un-hatched eggs were taken from each medium and observed for the presence of fungal pathogens using microscopy. Another batch of three samples of un-hatched eggs from each treatment was also inoculated on Sabourand dextrose agar (SDA) using Egg-Agar Transfer technique to observe for fungal growth. Mycelial growth was inhibited in fungal infected eggs treated with 2.75 ug/ml for 24 h and the 5 mg/L malachite green for both 1 h and 24 h. The mortality rate was 100% in fertilized C. gariepinus eggs exposed for 24 h to 0.275 and 2.75 ug/ml of pyocyanin. The mortality rate was least in the malachite green followed by the control treatment. Embryonic development was observed to be arrested in the eggs treated with the two pyocyanin concentrations as they maintain their color but showed no development beyond the gastrula stage, whereas viable eggs in the control and malachite green treatments developed fully into healthy hatchlings. Furthermore, microscopy of the un-hatched eggs revealed the presence of a protozoan ciliate; Colpidium sp. (Tetrahymenidae), as well as a pathogenic fungus; Saprolegnia sp. in the control, but not in the malachite green and pyocyanin treatments. Growth of Saprolegnia sp. was also observed in SDA culture of un-hatched eggs from the control, but not from pyocyanin and malachite green treated eggs. Pyocyanin treatment of incubated eggs of Clarias gariepinus effectively prevented fungal infection in the eggs, but also arrested the development of the embryo. Therefore, crude chloroform extract of pyocyanin from Pseudomonas aeruginosa cannot be used in the control of Saprolegniasis in incubated Clarias gariepinus eggs at the concentration and duration tested in this study.
Causal Factors of Mass Mortality of Hatchery Reared Clarias gariepinus fry during Exogenous Feeding
(AkiNik Publications, 2021) Anifowose O. R.; Oladosu G. A.; O. O. Oladele
The study investigated the causal factors associated with mass mortality of hatchery-reared Clarias gariepinus Burchell 1822 fry during exogenous feeding. A feeding trial and fry re-infection trial were conducted using four different starter diets. The food samples were fed to 480 post-yolk-absorbed fries for 21 days in two replicates. Samples of dead fry were cultured for bacteria using standard methods. The total aerobic and coliform were significantly higher in all food samples, meanwhile, alkaline pH (9.25±0.34) and low dissolved oxygen (4.5±1.08) were not significantly different (P>0.05) in all water tanks. The bacterial pathogens isolated from dead fries were Aeromonas hydrophila Stainer, 1943 and Pseudomonas aeruginosa Migula, 1990, whereas significantly higher mortality in experimentally infected fry was observed (α < 0.05). Mass mortality of C.gariepinus fry observed in this study was associated with bacterial pathogens, bacterial contamination of food, alkaline pH, and low dissolved oxygen
Clinicopathological features of arborescent organ necrosis syndrome in Clarias gariepinus (Burchell 1822)
(Faculty of Veterinary Medicine, University of Ibadan, Ibadan, Nigeria, 2013) Oladosu G. A.; Tijani M. O.; Akpavie S. O.; Adedeji O. B.
Some teleosts such as the African catfish (Clarias gariepinus) posess accessory respiratory organs (arborescent organ) which enable them to breathe atmospheric air in hypoxic conditions. Arborescent organ necrosis syndrome is a relatively new disease condition of farmed African catfish in Nigeria. There is only one report of this syndrome in the African catfish, although several anecdotes of its occurrence exists. Six freshly dead catfishes were collected from two farms during a disease outbreak where severe high mortalities were recorded. At necropsy there was severe necrosis of the arborescent organ. Other gross lesions observed included severe gill hyperaemia and severe depigmentation of the skin. Histopathology revealed severe necrosis and non- suppurative inflammation of the arborescent organ and gills, hepatocellular vacuolar degeneration and severe necrosis of the haematopoietic and non haematopoietic elements of the trunk kidney. Three organisms namely Aeromonas hydrophila, Pseudomonas putida and Salmonella subsp IIIB were isolated from the necrotic arborescent organs and the dorsal and trunk kidneys. All the isolates were susceptible to ciprofloxacin. No mortalities were recorded on affected farms a day following the administration of ciprofloxacin to affected catfishes. Although this is not the first report of this syndrome in the African catfish, it is notable that the organisms isolated in this case differ from what was isolated (Enterobacter cloacae and Aeromonas sobria) in the previously reported case.
Common diseases of fish encountered in different culture systems
(Department of Veterinary Public Health and Preventive Medicine, University of Ibadan, 2014) Oladosu G. A.; Adedeji O. B.
Comparative growth performance and survival of hatchery reared African catfish fry (Clarias gariepinus Burchell 1822) fed on live and artificial diets
(Akinik Publications, 2022) Anifowose O. R.; Oladosu G. A.; Oladele, O. O.
Background: Feed determines to a large extent the sustainability in aquaculture since the survival and growth of the fish fry depends on the quality of feeds. The comparative growth performance and survival in Clarias gariepinus fry fed with live and artificial feeds were carried out. Methods: Four hundred and eighty healthy fries collected from a commercial hatchery were randomly divided into four experimental groups of 40 fry with three replicates for each group, and fed with four different feeds (three live feeds and one artificial feed) to differentiate each group; Artemia Lush® (AL), Artemia Inve® (AI), Dried-ground Shrimp (S), and artificial feed Durante® (D) for three weeks. The proximate composition of feed samples was analyzed, Physico-chemical parameters and microbiological analysis of water in experimental tanks were analyzed on weekly basis. The fish were assessed for growth performance and survival on weekly basis. Results: There was a significant difference of P< 0.05 in all proximate compositions of the feeds analyzed, there was no significant difference (P> 0.05) in the Physico-chemical parameters of water in the experimental tanks within twenty-one days. The final weight, final length, specific growth rate, and survival of fry fed with live feeds Artemia were similar to artificial feed Durante® but the economic analysis was reduced in artificial feed compared to live feeds while fry fed with Dried-ground Shrimp had poor growth and survival rate. Conclusion: The feeding of live and artificial feeds to Clarias gariepinus fry within the first twenty-one days produced a similar growth response and survival rate but artificial diet required reduced cost than live diets while dried-ground shrimp should not be recommended for feeding Clarias gariepinus fry.
Completion report on technical training in best hatchery management practices for hatchery operators in the Niger-Delta
(USAID | NIGERIA, 2017) Oladosu G. A.
This training program for capacity building in hatchery management was proposed to mitigate skills gap earlier observed during the technical assessment of catfish hatcheries in the Niger Delta for infrastructural upgrade that was conducted in 2014. Of the twelve (12) catfish hatcheries selected for facility upgrade, eight (8) were empowered with production facilities following competitive bidding, while the entire twelve (12) were recalled to provide two (2) persons for capacity building in best hatchery management practices. However, only twenty-two (22) out of the expected twenty-four (24) participants attended the training program, as two (2) farms namely Zezi farms, Benin, Edo State and Segfun farms Calabar, Cross River State were represented by one trainee each. Pre-training evaluation conducted to determine the areas of critical deficiencies revealed the need to improve skills in all areas of controlled catfish propagation since challenges indicated by participants as intractable for them cut across all areas of controlled fish breeding. The modules for the training that took place in Port-Harcourt, Rivers State, between the 16th and 19th of May 2017, comprised of technical and practical sessions. Seven (7) technical sessions (TS) were delivered in a 67 slides power point presentation at Sparklight Hotel, GRA Phase 3, and seven (7) hands-on, practical sessions (PS) were conducted in the hatchery of Mayuel Fisheries belonging to one of the trainees. Controlled spawning of Clarias gariepinus by the dry stripping method was carried out at Mayuel Fisheries, Port-Harcourt using male and female broodstock procured from another farm within Port-Harcourt metropolis. All aspects of seed propagation techniques such as broodstock selection, induction of ovulation, milt procurement, fertilization, egg incubation, fry nursing, fry rearing, biosecurity and disease control were demonstrated within the 4-day period of training. In their post training evaluation, the trainees adjudged both the technical and the practical sessions as timely, appropriate and excellently delivered, providing insights that will be helpful in overcoming their challenges, since errors of the past were fully exposed and addressed. Some recommendations were made in the action plan drawn by the trainees to round-up the training program
Design and construction of a shrimp hatchery for the breeding of the black tiger shrimp Peneaus monodon
(Fisheries Society of Nigeria, 2009) Ayinla O. A.; Anyanwu P. E.; Atakpu J. A.; Ebonwu B. I.; Hamzat M. B.; Ihimekpen F. A.; Oladosu G. A.; Adeleke T. A.; Matanmi M. A.; Afolabi E. S.; Oguntade O. R.; Ayaobu-Cookey I. K.; Asikhia G. I.; Oseni A.; Olaluwoye L. B.; Ajijo M. R.
A shrimp hatchery for the breeding of the black tiger shrimp, Penaeus monodon was constructed the Nigeria Institute for Oceanography and Marine Research in 2008 by the reconstruction of an existing old shrimp hatchery. The new shrimp hatchery comprises of the following: water treatment, water storage, broodstock maturation, spawning/incubation, nursery and micro-algae units. The design included the construction of a concrete sump for the collection and treatment of wastewater before disposal, in addition to an acration unit equipped with root blower for adequate supply of dissolved oxygen. The reconstructed NIOMR shrimp hatchery has been successfully used for the production of post larvae, which are presently being reared to adult shrimp in concrete tanks. The successful completion of the shrimp hatchery and breeding of P. monodon has confirmed that the species can be spawned and reared to adult size in Nigeria for local and export markets.
Detection of Saprolegnia species on incubated eggs of Clarias gariepinus (Burchell 1822) using morphological and molecular characterization
(Association of Nigerian Fisheries Scientists (ANIFS), 2019) Fagbohun O.; Oladosu G. A.
Fungal infection of incubated eggs suspected to be one of the causal factors of poor hatching rates was studied on eggs collected from selected hatcheries in Ibadan, Nigeria. Morphology of the hyphae and the reproductive organs of fungus isolated with Sabouraud dextrose agar (incubated at 25°C for 48 hours) was conducted. Also, polymerase chain reaction (PCR) was used to detect and amplify the internal transcribed spacer 2 (ITS-2) and 5 'end region of 28S (D1-D2 region) of ribosomal RNA genes of the fungus. Hyphae and reproductive organ structures observed were typical of Saprolegnia spp.. while the PCR amplified the target nucleotide sequence in the fungal isolate. These findings confirmed the involvement of Saprolegnia spp. in mycosis commonly observed in incubated catfish eggs, and should be considered in the control of poor egg hatching rates and mass mortality of hatchlings and fry.
Detection of Saprolegnia species on incubated eggs of Clarias gariepinus (Burchell 1822) using morphological and molecular characterization
(Association of Nigerian Fisheries Scientists (ANIFS), 2019) Fagbohun O. A.; Oladosu G. A.
Fungal infection of incubated eggs suspected to be one of the causal factors of poor hatching rates was studied on eggs collected from selected hatcheries in Ibadan, Nigeria. Morphology of the hyphae and the reproductive organs of fungus isolated with Sabouraud dextrose agar (incubated at 25°C for 48 hours) was conducted. Also, polymerase chain reaction (PCR) was used to detect and amplify the internal transcribed spacer 2 (ITS-2) and 5 'end region of 28S (D1-D2 region) of ribosomal RNA genes of the fungus. Hyphae and reproductive organ structures observed were typical of Saprolegnia spp.. while the PCR amplified the target nucleotide sequence in the fungal isolate. These findings confirmed the involvement of Saprolegnia spp. in mycosis commonly observed in incubated catfish eggs, and should be considered in the control of poor egg hatching rates and mass mortality of hatchlings and fry.
Efficacy of silt and powdered milk in the removal of stickiness of fertilized eggs of Clarias gariepinus
(Faculty of Agriculture, University of Benin, Nigeria, 2004) Oladosu O. O.; Oladosu G. A.; Yakubu A. F.
Two batches of Clarias gariepinus eggs each were treated with autoclave-sterilized silt (25ml/L of water) and powdered milk (18g/L of water) respectively for 45minutes prior to incubation. A third batch of eggs that was not treated was incubated immediately after fertilization to serve as control. The three water quality parameters observed for all the treatments including temperature, dissolved oxygen and pH are within acceptable limits for Clarias gariepinus. They range from 26.7° C to 26.8°C for temperature, 5.9mg/L to 6.1mg/L for Dissolved Oxygen and 6.9 to 7.4 for pH. Hatching rates and the percentage of eggs that were free (unattached) were observed to be significantly highest in the batch treated with silt, which recorded 60.55% free eggs and 64 % hatching rate, as compared to the batch treated with powdered milk which recorded 22.0% free eggs and 38% hatching rate. The control (untreated) also recorded 10.2% free eggs and 32.6% hatching rate. This observation showed that silt is a more effective de-adhesive agent in the control of stickiness of fertilized C. gariepinus eggs and an indication that silt particles may not have adverse effect on the hatching of eggs.
Environmental induction of natural spawning in Gymnarchus niloticus (Cuvier 1829) in earthen pond
(Blackwell Science, 1997) Oladosu G. A.
Evaluation of monoclonal antibodies in immunofluorescence assay for rapid quality control of Peste des petits ruminants (PPR) vaccine.
(Elsevier B.V., 2023) Oyedele H. A.; Bodjo C. S.; Diallo H.; Gelaw H. B.; Baziki J. D.; Chitsungo E.; Rahamatou C.; Boukary M.; Fikru H.; Oladosu G. A.; Nwakpa N.
Peste des petits ruminants (PPR) is an acute viral disease of small ruminants with morbidity and mortality rates as high as 90 % and 100 % respectively. Vaccination using a homologous live-attenuated vaccine is the main control strategy available in endemic countries, and ensuring the quality of these vaccines is of utmost impor tance for PPR control. Currently, the quality control test to determine vaccine potency is the time-consuming and subjective tissue culture infectious dose (TCID 50 ) assay involving titration on Vero cell line and reading the cytopathic effect (CPE) using light microscopy. In this study, an indirect immunofluorescent antibody test (IFAT) was evaluated for PPR vaccines potency testing. Accuracy and repeatability of the IFAT were also determined. Six PPR vaccine batches were produced and tested simultaneously by CPE reading and the IFAT. Vero cells were seeded in 96-well plates, and infected with 10-fold serial dilutions of the vaccines. CPEs were read continuously from day 3–14 after infection, and titers expressed in TCID 50 /ml. From 3–7 days post-infection, cells were fixed, incubated with anti-N and anti-H monoclonal antibodies (mAbs), and stained with a secondary antibody labeled with a fluorescent tag. Fluorescent foci of infection were detected using a fluorescence microscope, and titers were calculated as TCID 50 /ml. The results indicated that from day 4, the IFAT gave similar results to CPE readings of day 14 (intraclass correlation coefficient, ICC = 0.957, P < 0.0001). This is a three-fold reduction in time and can be used for rapid PPR vaccine potency evaluation. However, there was no difference observed between the results of the two mAbs (ICC = 0.910, P < 0.0001) indicating that both are equally sensitive and rapid. This result indicates that the IFAT may be more suited for potency testing of PPR vaccines as it saves time and minimizes analyst-related variability associated with CPE reading.