Search

Plankton population of shrimp and shrimp-GIFT (Genetically Improved Farmed Tilapia) culture ponds were studied. The present study was carried out to estimate phytoplankton and zooplankton abundance and diversity in mono and polyculture systems. A total of 13 phytoplankton genera of cyanophyceae, chlorophyceae, bacillariophyceae, euglenophyceae, rhodophyceae and dinophyceae were recorded from the monoculture ponds while 12 phytoplankton genera were measured from shrimp-tilapia mixed culture ponds. Six genera of zooplankton under copepod, rotifer, cladocera, ostracoda were identified in monoculture system and 7 genera were found from polyculture ponds. The numbers of phytoplankton and zooplankton species were recorded to be significantly (p

The effect of cypermethrin pesticide on juvenile rohu (Labeo rohita) was determined in captive condition. Live and healthy rohu (average initial weight 21g) were exposed to five concentrations of Cypermethrin 0.63, 0.13, 0.025, 0.005, 0.001 ppm and one control group (no pesticide) with two replications for each treatment. The mean temperature and pH in the experimental tanks were 27.53±0.41ºC and 7.22±0.013 ppt, respectively. The highest growth recorded in control tank was 0.2g per week, where as nosignificant growths were found in 0.001 ppm and 0.005 ppm concentration. Rohu reared in the 0.13 ppm had the lowest growth. The median lethal concentration values were found at 0.025, 0.005 and 0.001 ppm for 9th, 17th and 20th day, respectively. Behavioral patterns were observed in both lethal 0.63, 0.13 ppm and sub lethal concentration 0.025 ppm. L. rohita in toxic media exhibited erratic and darting movements with imbalanced swimming activity, which might be due to the malfunctioning of neurotransmitters, followed by hyper and hypo opercula activity, loss of equilibrium and mucus secretion all over the body were observed

Staphylococcus aureus is an emerging pathogen from dairy animals that can form biofilms in the udder of dairy cows affected by mastitis. The use of antibiotics in dairy farms leads to a decrease in bacteria, finally making healthy food. The aim of this study was to determine the occurrence, antibiotic susceptibility, and biofilm forming ability of S. aureus isolated from cow milk. A total of fifteen raw milk samples were collected from Mohammadpur, Narayangonj, Savar, Bosila, Siddheshwari and Norshingdi dairy farms for isolation of S. aureus. All the samples were highly loaded with Staphylococcus and the total staphylococcal count ranged from 105 to 106 cfu ml-1. Biochemical tests (TSI, catalase, oxidase, motility, MR/VP etc.) were performed for the confirmation of the Staphylococcal isolates. The 100% resistance was observed against oxacillin, erythromycin, cotrimoxazole, amoxicillin, cefixime and vancomycin. In contrast to these results, the isolates showed 100% sensitivity to gentamicin and ciprofloxacin. The sensitivity against kanamycin and tetracycline was observed to be variable. The present study reveals the presence of multidrug resistant S. aureus in milk. Therefore, appropriate control measures like proper sanitation of the place where the milking cows live, maintenance of hygiene before and after milking, using proper mechanical methods for milking with strict maintenance of sanitation etc. are needed to be ensured. South Asian J. Agric., 8(1&2): 13-19

Tilapia (Oreochromis niloticus) is one of the most promising aquaculture species in Bangladesh, the culture of which is mostly dependent on the supply of hatchery-produced seed. Published information on genetic monitoring and genetic variability of the hatchery-reared tilapia population is rare in Bangladesh. Therefore, intra- and inter-population genetic variations were estimated among the five mono-sex tilapia populations collected from the matchday-kanon, khan, nancy, city, and brac hatcheries located at different districts in Bangladesh. Random amplified polymorphic DNA (RAPD) markers were amplified from tilapia’s muscle DNA of each of the five populations using ten decamer random primers. The primers produced a total of 181 scorable bands of which 64.1% were found to be polymorphic ranged in molecular size from approximately 100bp to 2000bp. The brac population obtained the highest genetic variability (51%) of overall polymorphic loci and the lower index was estimated (55-62%) in that population with the four others in pair-wise similarity comparison. Moreover, a common pattern of distinctive genetic variation was observed in the brac hatchery population when the genetic differentiation (FST), gene flow (Nm) and genetic distance (D) had been analyzed. The distinctiveness was also supported from the unweighted pair group method of arithmetic mean (UPGMA) dendrogram analysis where the five populations aligned into two clusters- the brac alone belonged to one and the rest of the four grouped into another. Our overall findings reveal that a low level of genetic variation exists in the current tilapia populations of Bangladesh except in the brac hatchery population where broodstock is known to be well managed. This low level of genetic variation of the tilapia hatchery population will have a seriously detrimental effect on this species and its overall production if the genetic quality is not maintained.

The present study evaluated the effect of probiotic Lactobacillus sp. against pathogenic bacteria Vibrio harveyi in freshwater prawn Macrobrachium rosenbergii. The bacteria were isolated from the gut of prawn and identified using biochemical and PCR tests. Inoculation of probiotic (9 log CFU/g) and pathogenic bacteria (5 log CFU/g) mixture was employed for in vitro test. The in vivo challenge test was conducted in glass aquaria (45 × 30 × 30 cm3) and also in an earthen pond (70 m2, 1 m depth) for 8 weeks, individually. In both cases, only the treatment group was provided probiotic (9 log CFU/g) incorporated feed. Growth, digestibility, and immune response of prawn were determined. Both in the in vitro and in vivo test, V. harveyi growth was found to be reduced significantly at 8 hr (from 5 to 4 log CFU/g) and after 50 days (from 7 to 6 log CFU/g) of probiotic administration, respectively. In the pond, higher growth and better digestibility were found in the treatment group (WG%, 549. 30 ± 40.02%; SGR%, 3.12 ± 0.10%; amylase, 1.23 unit/mg; protease, 2.47 unit/mg) compared to the control group (WG%, 310.77 ± 18.68%; SGR%, 2. 35 ± 0.08%; 0.7 unit/mg; protease, 1.82 unit/mg). The immune response was found to be significantly different (P

Recently mud crab (Scylla olivacea) has emerged as a potential export commodity. Its farming is increasing rapidly in Bangladesh because of its lucrative price and high demand in international market. However, the farming or fattening of mud crab is totally dependent on capture of wild crablets. A huge quantity of mud crabs is being caught indiscriminately from nature and thus putting intense pressure on its wild stock, which is a major concern of conservation. Imposing ban at peak breeding season and setting a legal capture size are considered effective management tools for safe migration and spawning of berried females. There is contradictory information on breeding season of mud crab in Bangladesh. Thus, it is crucial to identify the peak breeding season of it and to formulate conservation policies to protect the berried crabs. Live crabs were collected year-round from the river adjacent to southwest part of Sundarbans. Although mud crab breeds throughout the year, March–April was identified as the peak breeding season of it. The second peak was observed in August–September. The highest abundance of crablets (1–2 months age) was recorded in May–June, and the lowest in January–February. Immature crablets were found all through the year that proves that mud crab is a continuous breeder. The highest amount of GSI value (11.6) was observed in February–March, which indicates that the breeding is very near. The size at first maturity (M50) was estimated as 95.5 mm CW which lied at size class 91–100 mm (CW). The findings from the study will assist in fixing up the banning time and thus protecting the mother crabs; and will assist in formulating police to conserve and protect juvenile crabs in the sense that the minimum legal capture size of crabs will allow the adults to mate and spawn at least once before their capture., Peak breeding season; Spawning time; Size at maturity; Mud crab Scylla olivacea, Agriculture; Animal science; Fishery management; Environmental science; Environmental management; Nature conservation

To determine antagonistic effect of Clostridium butyricum against Vibrio harveyi and its probiotic effect on growth performance, digestibility and immune response of fresh water prawn, Macrobrachium rosenbergii juveniles were examined following feeding with C. butyricum incorporated feed for 60 days. Significant reduction of V. harveyi growth was found at 8 hr and onward in in-vitro and at 10 days and onward in in-vivo challenge test. After rearing prawn with the bacteria in feed treatment for 60 days, body weight and growth rate of prawns was significantly higher (p 0.05) compared to control group. This study revealed that probiotic, C. butyricum incorporated diets were found to be beneficial for M. rosenbergii culture in terms of hindering the growth of pathogenic bacteria and increasing the growth, protease and amylase activities of prawn. Results from this study will be helpful to improve fresh water prawn farming.

DOI: 10.20286/ajlsr-040288 This study was conducted to detect the presence of enterovirulent Escherichia coli strains using PCR technique in some selected unhygienic and hygienic traditional shrimp farms in Bangladesh. The target genes chosen for this investigation included: the phoa housekeeping gene (present in all E. coli ); the lt1, lt2 and st1 genes of ETEC; the vtverotoxin, and eae virulence genes of EHEC and EPEC, respectively. Six pairs of oligonucleotide primers were designed to amplify internal fragments of these genes by PCR to generate PCR products that were analyzed by gel electrophoresis. The presence of E. coli strains were determined by visualization of strain specific band comparing with a 100 bp DNA size marker in UV transilluminator. The results revealed that water of both hygienic and unhygienic farms were highly contaminated with E. coli followed by sediment and shrimp. Whereas, only water, sediment and shrimp of unhygienic farms were found to be contaminated with virulent E. coli strains. Among the virulent E. coli strains, ETEC and EPEC strains were detected in unhygienic farms, but no EHEC strain was detected. However, no contamination with virulent E. coli strains was found in hygienic farms.

The study was conducted to detect faecal coliforms and pathogenic bacteria in shrimp and shrimp farms. Although coliforms are widely distributed in the environment, but only a small percentage are pathogenic to humans. The presence of pathogenic bacteria in shrimp causes several waterborne infections in humans that are worldwide concerning issues. In order to better determination of the health risks that are associated with the exposure to pathogenic bacteria, a multiplex PCR system was used for the rapid detection of pathogenic Aeromonas sp., Clostradium sp., Listeria sp., Salmonella sp., Shigella sp., Vibrio sp. and Staphylococcus sp. in the water, sediment and shrimp. The target genes were chosen for this investigation included: Aer gene for Aeromonas sp., hilA gene for Salmonella sp., virA gene for Vibrio sp., Sec gene for Staphylococcus aureus, neurotoxin gene type A, B, E, F for Clostridium botulinum, internalin gene for Listera sp. andipaH gene for Shigella sp. Seven pairs of specific primers were used to amplify internal fragments of these genes by PCR to generate PCR products that could be analyzed and confirmed with relative ease by gel electrophoresis. The presence of Aeromona and Vibrio sp. were found in the water, sediment as well as in the shrimp that were dominant among other bacteria species. On the other hand, Salmonella and Clostridium group was found in the sediment of one sample but there is no evidence of Listeria, Staphylococcus and Shigella group in the farms. All of the samples contained relatively large number (1100 to ≥2400 cfu/g) of coliform bacteria. The unhygienic condition and polluted water source could be the major reasons for the occurrence of these types of pathogenic bacteria in the shrimp farms in this area. The result revealed that the PCRbased rapid detection system described in this study is a powerful method for routine monitoring and risk assessment of water quality in the shrimp farms and could be an effective tool for disease studies in our shrimp sector.