MBV infection in various stages of black tiger shrimp (Penaeus monodon)

MBV infection in various stages of Penaeus monodon were studied. In hatcheries, MBV infection was detected early in nauplii stage using PCR technique, whereas rates of infection of 11.15-49.50% were observed in PL1 using histological technique, rising up to 15.26-100% in PL 10. In earthen ponds, the infection in PL15 was initially in the range of 68.68-96.00%. The infection was decreased toward the end of the first, second and third month of rearing period ranging between 13.63-54.83%. The laboratory trial showed that types of feed might affect the rate of MBV infection of larvae. Postlarva fed with artemia showed lowest infection rate at 29.41±7.98%, whereas the infection rates of shrimp fed with minced cockle flesh and commercial feed were 39.09±12.08% and 52.81±11.91, respectively. In stress test trial, a significant MBV infection was detected in the group of larvae that were raised with 25ºC and 34ºC and the salinity at 6 ppt and 18 ppt for 12 hours then rearing in normal condition for 3 days. In the 24 hour-stress trial, and transferred to normal condition for 7 day, the groups that were exposed to stress conditions had significantly higher rates of infection than the control group (p<0.05). The 24 hour - transportationcondition resulted in highest MBV infection rate (73.61±1.25%). From the present study, it was concluded that MBV infection in larvae from hatcheries increases with period of rearing and stress exposure, but the infection tended to decreased with rearing period in earthen pond condition. Proper feeding management and prevention of stress conditions could reduce of MBV infection in black tiger shrimp

Effect of dietary pigment on growth performance and disease resistance in black tiger shrimp post larva (Penaeus monodon, Fabricius)

Effects of dietary pigment on survival and disease (white spot syndrome virus: WSSV) resistance in black tiger shrimp post larva (Penaeus monodon, Fabricius) (PL15) for a 30-day period were studied. The results showed that not only was mean survival of black tiger shrimp (PL15) fed with supplementation of Lucarotene or Betatene at 125 mg/kg diet significantly higher (P<0.05) but also the body color was increased. There were no effects of dietary pigment on mean weight, percent weight gain and WSSV resistance. However, mean WSSV resistance of black tiger shrimp (PL15) fed diet containing Lucantin pink 50 mg/kg diet, Spirulina 30 g/kg diet or Betatene 125 mg/kg diet was higher than that of control

Effects of Thai medicinal plants on pathogenic bacterial, growth performance, health condition and disease resistance in black tiger shrimp (Penaeus monodon Fabricius)

Chemical analysis of turmeric (Curcuma longa) extracts using TLC/densitometry, showed an extract contain 21.57%w/w of three important curcuminoids: curcumin, desmethoxycurcumin and bisdesmethoxycurcumin. GC and MS were used to analyze volatile oils. Aromatic turmerone, α-turmerone and zingiberene were also obtained. Qualitative and quantitative analyses alcoholic extract of Andrographis paniculata using TLC, revealed that the extracts contain three important compounds in total lactone of 30.49% w/w. There are andrographolide,14-deoxy-11-12-didehydroandrographolide and neoandrographolide. TLC-chromatogram of Clinacanthus nutans extract after reacted with anisaldehyde/sulfuric acid showed a 9 key compounds, while preliminary neutralization test of the compounds revealed that there were active compounds against HSV-1 virus. In vitro efficacy test revealed that Curcuma longa and Andrographis paniculata extracts at 250 and 1,500 mg/L could eradicate 15 isolates of Vibrio spp. which were isolated from infected shrimps. Effects of medicinal plant extracts incorporated into the diet on shrimp immune responses were investigated. Shrimp fed diet containing Clinacanthus nutans extract at 20 mg/kg of diet had good growth, FCR and immune responses. The shrimp that were fed diet containing Curcuma longa extracts at 25 mg/kg of diet for 7-14 days showed high resistance to Vibrio harveyi. Likewise, the shrimp fed Andrographis paniculata extract at 25 mg/ kg of diet for 14 days had a higher resistance to WSSV. Incorporating the medicinal extracts at higher levels resulted in reduction in diet palatability which consequently had an effect on a decrease in growth, immune responses and resistance to bacterial and WSSV infection

The application of fluorescence in situ hybridization (FISH) technique for studying the microbial communities in intestinal tissues of white shrimp (Penaeus vannamei)

Fluorescence in situ hybridization technique is very useful for the evaluation of microbial communities in various environments. It is possible to apply this technique to study the intestinal microflora in white shrimp (Penaeus vannamei). Different fixatives and storage temperature were tested in this technique. It was found that fixation with 10% buffered formalin for 12 hours and changed to 70% ethanol shown positive results when compared to the fixation with Davidson's fixative or RF fixative. The best signaling was obtainedfrom the samples which were stored in -20ºC. By using the DNA probe targeted to the Eubacteria domain (EUB338 probe, 5′-GCT GCC TCC CGT AGG AGT-3′) labeled with fluorescein as a hybridizing probe, it was found that most intestinal microflora were aggregated with the intestinal contents, or dispersed in the lumen. There was not evidence of the attachment of the microflora with the intestinal epithelium in this study

Effects of aflatoxin B1 on sex reversed red tilapia (Oreochromis niloticus Linn. x O. mossambicus Peters)

In the present study an 8-week feeding trial was conducted on sex-reversed red tilapia (Oreochromis niloticus x O. mossambicus) to assess the effects of diets containing various levels (i.e. 0, 50, 100, 500, 1,000 and 2,500 ppb) of aflatoxin B1 (AFB1) on growth performance, blood parameters and histopathology of fish. Results showed that experimental fish fed AFB1 with 2,500 ppb showed significant reduced weight gain and hepatosomatic index. However, feed supplemented with AFB1 caused no effect on survival rate of the fish in each group. Feeding high level of AFB1 (1,000 and 2,500 ppb) also affected some blood parameters i.e. hemoglobin and plasma protein. Some histopathological changes (i.e. cloudy swelling, inflammation and cell necrosis) were observed in liver and pancreas of fish fed AFB1 with 1,000 and 2,500 ppb. The severity of symptoms was related with concentration of AFB1. This indicated that AFB1 may impair the functioning of fish hepatocytes. However, no residue of AFB1 was detected in fish tissues at completion of the feeding period. It can be concluded that fish feeds occasionally contaminated with AFB1 directly affected fish health but may have no negative impact on fish consumers

Mud crab susceptibility to disease from white spot syndrome virus is species-dependent

<p>Abstract</p> <p>Background</p> <p>Based on a report for one species (<it>Scylla serrata</it>), it is widely believed that mud crabs are relatively resistant to disease caused by white spot syndrome virus (WSSV). We tested this hypothesis by determining the degree of susceptibility in two species of mud crabs, <it>Scylla olivacea </it>and <it>Scylla paramamosain</it>, both of which were identified by mitochondrial 16 S ribosomal gene analysis. We compared single-dose and serial-dose WSSV challenges on <it>S. olivacea </it>and <it>S. paramamosain</it>.</p> <p>Findings</p> <p>In a preliminary test using <it>S. olivacea </it>alone, a dose of 1 × 10⁶WSSV copies/g gave 100% mortality within 7 days. In a subsequent test, 17 <it>S. olivacea </it>and 13 <it>S. paramamosain </it>were divided into test and control groups for challenge with WSSV at 5 incremental, biweekly doses starting from 1 × 10⁴and ending at 5 × 10⁶copies/g. For 11 <it>S. olivacea </it>challenged, 3 specimens died at doses between 1 × 10⁵and 5 × 10⁵copies/g and none died for 2 weeks after the subsequent dose (1 × 10⁶copies/g) that was lethal within 7 days in the preliminary test. However, after the final challenge on day 56 (5 × 10⁶copies/g), the remaining 7 of 11 <it>S. olivacea </it>(63.64%) died within 2 weeks. There was no mortality in the buffer-injected control crabs. For 9 <it>S. paramamosain </it>challenged in the same way, 5 (55.56%) died after challenge doses between 1 × 10⁴and 5 × 10⁵copies/g, and none died for 2 weeks after the challenge dose of 1 × 10⁶copies/g. After the final challenge (5 × 10⁶copies/g) on day 56, no <it>S. paramamosain </it>died during 2 weeks after the challenge, and 2 of 9 WSSV-infected <it>S. paramamosain </it>(22.22%) remained alive together with the control crabs until the end of the test on day 106. Viral loads in these survivors were low when compared to those in the moribund crabs.</p> <p>Conclusions</p> <p><it>S. olivacea </it>and <it>S. paramamosain </it>show wide variation in response to challenge with WSSV. <it>S. olivacea </it>and <it>S. paramamosain </it>are susceptible to white spot disease, and <it>S. olivacea </it>is more susceptible than <it>S. paramamosain</it>. Based on our single-challenge and serial challenge results, and on previous published work showing that <it>S. serrata </it>is relatively unaffected by WSSV infection, we propose that susceptibility to white spot disease in the genus <it>Scylla </it>is species-dependent and may also be dose-history dependent. In practical terms for shrimp farmers, it means that <it>S. olivacea </it>and <it>S. paramamosain </it>may pose less threat as WSSV carriers than <it>S. serrata</it>. For crab farmers, our results suggest that rearing of <it>S. serrata </it>would be a better choice than <it>S. paramamosain </it>or <it>S. olivacea </it>in terms of avoiding losses from seasonal outbreaks of white spot disease.</p

Diversity and distribution of parasites from potentially cultured freshwater fish in Nakhon Si Thammarat

Twenty-one species from 16 genera of potentially cultured freshwater fish were examined for external and internal parasites. Ten individuals of each fish species were sampled from various places in Nakhon Si Thammarat. Eight groups, 72 species were identified and the majority was external (52 spp.). The parasites found were ciliated protozoan (2 spp.), myxozoan (2 spp.), monogenean (44 spp.), digenean (7 spp.), cestode (6 spp.), nematode (6 spp.), acanthocephalan (2 spp.) and crustacean (3 spp.). Monogenean was regarded as a major group of parasites with 44 species. Dactylogyrus (Monogenea) had the highest number of species (12 spp.), whereas Trichodina pediculus (Ciliophora) was the most widely distributed species observed from at least 7 fish species (7 families). Most of the parasites (72 %) found in this study were specific to their host species

Haematological studies of climbing perch (Anabas testudineus Bloch)

Some blood parameters of the climbing perch (Anabas testudineus Bloch) i.e. red (RBC) and white (WBC) blood cell count, percent haematocrit (HTC), hemoglobin, plasma protein as well as hepatosomatic index (HSI) were studied. There were no statistically significant difference (p>0.05) in average body weight and length of fish from the earthen pond and net cage culture, which were 16.85±1.46 g and 16.24±2.42 g, respectively, for the weight and 10.02±0.25 and 9.74±0.37 cm, respectively, for the length. Haematologicalstudies revealed that RBC, WBC including percent HTC levels of the fish from earthen pond and net cage were not significantly different (> 0.05). Whereas hemoglobin and serum protein concentration of the fish sampling from net cage were higher than those sampled from the earthen pond (p<0.05), with value of 12.21± 0.91 g/dl and 11.12±0.85 g/dl for hemoglobin and 4.61±0.50 mg/dl and 3.87±0.62 mg/dl for serum protein, respectively. HSI of the fish cultured in the earthen pond was significantly (p<0.05) higher than that of fish reared in net cage, with value of 1.93±0.12% and 1.66±0.12%, respectively

Production of killed vaccine from Streptococcus sp. and its application in sea bass (Lates calcarifer)

Fish with an average length of 3.0-4.0 inches vaccinated with formalin-killed vaccine of Streptococcus sp. either by intraperitoneal injection and immersion methods had a survival rate of 100% indicating that the vaccine is safe to be used with sea bass. The highest efficacy was received when the vaccine containing bacterin at 2.50x1010 CFU/ml. Injection of vaccine together with adjuvant (CFA) was highly effective against Streptococcus sp. infection. The relative percent survival (RPS) of fish injected with vaccine alone and vaccine plus adjuvant were 100 (10 days post vaccination), 54.06 and 92.29 (20 days post vaccination) and 31.58 and 73.68 (30 days post vaccination) respectively. The fish which received vaccine by hyperosmotic immersion showed higher resistance to the disease than by direct immersion with the RPS of 30.77 and 71.80 (10 days post vaccination), 9.75 and 70.73 (20 days post vaccination) and 7.14 and 16.67 (30 days post vaccination) for direct immersion and hyperosmotic immersion, respectively