A study was carried out to investigate antibiotic resistance patterns and plasmid profiling of Edwardsiella tarda isolated from farmed-cultured Heterobranchus longifilis in Lagos State, Southwest of Nigeria. A total o...A study was carried out to investigate antibiotic resistance patterns and plasmid profiling of Edwardsiella tarda isolated from farmed-cultured Heterobranchus longifilis in Lagos State, Southwest of Nigeria. A total of 44 Edwardsiella isolates were recovered from 80 fish samples collected from the 10 fish farms using selective random stratification. It was observed that Edwardsiella tarda isolates were 100% resistant to Amoxicillin, Chloranphenicol, Levofloxacin, Streptomycin and 90% resistant to Nalidixic Acid respectively. All the isolates were 100% susceptible to Spectinomycin and Ciprofloxacin, while Ofloxacin, Gentamycin, and Pefloxacin vary in their level of susceptibility with 90%, 80% and 70% sensitivity respectively. Conversely, 8 out of 10 fish farm locations studied were observed to have antibiotic-resistant strains, and 5 out of 8 drug-resistant strains were found to carry plasmid and the sizes of the plasmid ranges between 20.027 kb to 23.130 kb. The plasmid after treatment with mitomycin C and ethidium bromide were lost during the process of plasmid curing confirming that the multiple drug resistant exhibited by the isolates was plasmid mediated. There are fewer studies on antibiotic resistance in Edwardsiella tarda from aquaculture enterprises and this study provides further support to the view that there is a potential risk of transfer of resistant bacteria and their genes to human pathogen through the food chain. Although, in Nigeria there is no antibiotic product registered for aquaculture usage, yet fish farmers use them off-label for bacterial diseases prevention.展开更多
The present study was performed to investigate the influence of fish oil (FO), two terrestrial animal fats (lard (PL) and poultry oil (CF)) and three vegetable oils (palm kernel (PKO), sheabutter (SBO) and sunflower (...The present study was performed to investigate the influence of fish oil (FO), two terrestrial animal fats (lard (PL) and poultry oil (CF)) and three vegetable oils (palm kernel (PKO), sheabutter (SBO) and sunflower (SFO)) as the dietary lipid sources on the growth performance, nutrient digestibility, fatty acid (FA) composition and histology of Hetero-branchus longifilis. Six isonitrogenous and isoenergetic diets containing 6% of added fat from the lipid sources were formulated and used. Each diet was fed to triplicate groups of 20 fish. The lipid source influenced (P < 0.05) weight gain, specific growth rate, feed conversion ratio, hepatosomatic index and nutrient digestibility. Liver morphology of H. longifilis fed CF showed intense steatosis with hepatocytes containing numerous lipid vacuoles. However, fish fed PKO and SFO showed regular-shaped hepatocytes with few lipid vacuoles in the cytoplasm. Fillet FA profile of fish fed PKO, SBO, PL and CF diets had significantly higher (P < 0.05) concentrations of SFA and MUFA, but lower PUFA com-pared to fish fed FO and SFO diets. Fillet of fish fed the FO diet had higher (P < 0.05) concentrations of EPA and DHA compared with fish fed the other diets. The results of this study shows that alternative lipids sources could be used in H. longifilis diets however, inclusion of PKO or SBO in the diet of H. longifilis produced fillets with low concentrations of long chain n-3 PUFA.展开更多
This study aims to evaluate the production cost of Heterobranchus longifilis larvae reared in fertilized fish ponds. Experiment was carried out in two fish ponds. Each fish pond was filled with 200 liters of water and...This study aims to evaluate the production cost of Heterobranchus longifilis larvae reared in fertilized fish ponds. Experiment was carried out in two fish ponds. Each fish pond was filled with 200 liters of water and fertilized with dry poultry droppings (dose: 0.6 g.L-1) and zooplankton was inoculated with 83±13 individuals/L. Six days after inoculation of zooplankton, larvae of H. longifilis of 2 days after post-hatching were directly introduced into ponds with 300 individuals/m3. These larvae used exclusively zooplankton during the first 7 days. From the 8th day, larvae were fed with Coppens feed until 30 days. At the end, the survival rates were ranged between 58.33% and 56.67%. Final mean weights were brought up to all the ponds and were notsignificantly different (p > 0.05). The production costs ranged between 2.55 FCFA and 2.60 FCFA per fingerling with ratio production cost/weight gain around 0.80 FCFA/g in each pond. Then, this production system of fingerlings in fertilized ponds is very efficient and could be popularized in the rural fish farms.展开更多
文摘A study was carried out to investigate antibiotic resistance patterns and plasmid profiling of Edwardsiella tarda isolated from farmed-cultured Heterobranchus longifilis in Lagos State, Southwest of Nigeria. A total of 44 Edwardsiella isolates were recovered from 80 fish samples collected from the 10 fish farms using selective random stratification. It was observed that Edwardsiella tarda isolates were 100% resistant to Amoxicillin, Chloranphenicol, Levofloxacin, Streptomycin and 90% resistant to Nalidixic Acid respectively. All the isolates were 100% susceptible to Spectinomycin and Ciprofloxacin, while Ofloxacin, Gentamycin, and Pefloxacin vary in their level of susceptibility with 90%, 80% and 70% sensitivity respectively. Conversely, 8 out of 10 fish farm locations studied were observed to have antibiotic-resistant strains, and 5 out of 8 drug-resistant strains were found to carry plasmid and the sizes of the plasmid ranges between 20.027 kb to 23.130 kb. The plasmid after treatment with mitomycin C and ethidium bromide were lost during the process of plasmid curing confirming that the multiple drug resistant exhibited by the isolates was plasmid mediated. There are fewer studies on antibiotic resistance in Edwardsiella tarda from aquaculture enterprises and this study provides further support to the view that there is a potential risk of transfer of resistant bacteria and their genes to human pathogen through the food chain. Although, in Nigeria there is no antibiotic product registered for aquaculture usage, yet fish farmers use them off-label for bacterial diseases prevention.
文摘The present study was performed to investigate the influence of fish oil (FO), two terrestrial animal fats (lard (PL) and poultry oil (CF)) and three vegetable oils (palm kernel (PKO), sheabutter (SBO) and sunflower (SFO)) as the dietary lipid sources on the growth performance, nutrient digestibility, fatty acid (FA) composition and histology of Hetero-branchus longifilis. Six isonitrogenous and isoenergetic diets containing 6% of added fat from the lipid sources were formulated and used. Each diet was fed to triplicate groups of 20 fish. The lipid source influenced (P < 0.05) weight gain, specific growth rate, feed conversion ratio, hepatosomatic index and nutrient digestibility. Liver morphology of H. longifilis fed CF showed intense steatosis with hepatocytes containing numerous lipid vacuoles. However, fish fed PKO and SFO showed regular-shaped hepatocytes with few lipid vacuoles in the cytoplasm. Fillet FA profile of fish fed PKO, SBO, PL and CF diets had significantly higher (P < 0.05) concentrations of SFA and MUFA, but lower PUFA com-pared to fish fed FO and SFO diets. Fillet of fish fed the FO diet had higher (P < 0.05) concentrations of EPA and DHA compared with fish fed the other diets. The results of this study shows that alternative lipids sources could be used in H. longifilis diets however, inclusion of PKO or SBO in the diet of H. longifilis produced fillets with low concentrations of long chain n-3 PUFA.
文摘This study aims to evaluate the production cost of Heterobranchus longifilis larvae reared in fertilized fish ponds. Experiment was carried out in two fish ponds. Each fish pond was filled with 200 liters of water and fertilized with dry poultry droppings (dose: 0.6 g.L-1) and zooplankton was inoculated with 83±13 individuals/L. Six days after inoculation of zooplankton, larvae of H. longifilis of 2 days after post-hatching were directly introduced into ponds with 300 individuals/m3. These larvae used exclusively zooplankton during the first 7 days. From the 8th day, larvae were fed with Coppens feed until 30 days. At the end, the survival rates were ranged between 58.33% and 56.67%. Final mean weights were brought up to all the ponds and were notsignificantly different (p > 0.05). The production costs ranged between 2.55 FCFA and 2.60 FCFA per fingerling with ratio production cost/weight gain around 0.80 FCFA/g in each pond. Then, this production system of fingerlings in fertilized ponds is very efficient and could be popularized in the rural fish farms.
