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

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

Epizootic and pathogenesis of Taura syndrome virus (TSV) in black tiger shrimp (Penaeus monodon) cultured in southern Thailand

A research study was carried out on Taura syndrome virus (TSV) in P. monodon and P. vannamei cultured in earthen ponds of Songkhla, Satun and Pattani provinces. Infection rates of 38.33 and 34.21% were detected in P. monodon and P. vannamei, respectively. The injection of Taura virus isolated from the infected specimens of both species in 3-5 g P. monodon juveniles then reared in seawater with 3.25 and 5.74 mg DO for a 15-d period. The mortality rates of 16.67 and 30% were recorded in shrimps injection with TSV solution and reared in 5.74 mg DO seawater, while mortality increased to 50-70% when reared in 3.25 mg DO seawater. TSV infected P. monodon showed aggregated multifocal necrotic foci in epithelial tissues of subcuticle, stomach, haemopoietic tissue and to lesser extent in gill, tegmental and antennal glands. Application of in situ hybridization technique with DNA probes to examine the target organ of TSV showed specificity of infection for subcuticle, epithelial tissues of stomach, intestine and haematopoietic tissue is major target organ of infection, with densely dispersed inclusion bodies and multifocal necrotic foci. Penetration of TSV into the cells can cause damage to tissue of antennal gland, gill, lymphoid organ, subcuticle and connective tissue, remarkably noted of no infection in hepatopancreas, nervous tissue, anterior midgut cecum and epicardium tissue

Pathogenesis and virulence of Vibrio harveyi from southern part of Thailand in black tiger shrimp, Penaeus monodon Fabricius

Ten isolates of bacteria were performed from diseased black tiger shrimp collected from farms in Nakhon Si Thammarat, Patthalung, Songkhla, Satun and Patthani. All isolates belonged to Vibrio harveyi, forming rounded colonies with smooth periphery and hemolysis of red blood cells. The colonies appearedgreen and yellow on TCBS selective media and indeeded both luminescent and non-luminescent groups. To support good growth as cell proliferation, an addition of 2-8% salt to the culture media was required. Sensitivity tests against antibiotics showed that all ten isolates were sensitive to chloramphenicol, norfloxacin, trimethoprim-sulfamethoxazole, oxolinic acid, oxytetracyclin and sarafloxacin at 80, 60, 50, 40, 40 and 30%, respectively. When 12-15 g juvenile shrimp were tested for the virulence by injection, the isolates were highly virulent with OD at 640 nm in the range 0.007-0.139. The bacteria concentration of 1.60×106 - 7.27×107 CFU/ ml caused 50% juvenile mortality in ten days. The physiological changes after susceptibility included a decline in the blood cells (p<0.05), higher plasma pH (p<0.05), decrease in serum protein within 24 h (p<0.05), and a return to normal levels within 48 h. There were no differences in blood sugar levels and phenoloxidase activity between the healthy and the infected individuals. Histological study showed that at an early period of susceptibility, there were swollen tubular lumen, minor cell degeneration of the hepatic tubules and lymphoid organs and aggregation of blood cells around the degenerating cells. During 7-day susceptibility period, there was large scale cell degeneration of the hepatopancreas, lymphoid organs, gills and blood formingorgans with a great extent of blood cell aggregation and eventually mortalities occurred. During 14 day susceptibility period, there was almost entire degeneration of cells in hepatic tubules and lymphoid organs causing hepatopancreatic tubular necrosis. During this period, juveniles did not accept feed and total mortality occurred