Effects of ochratoxin A and deoxynivalenol on growth performance and immuno-physiological parameters in black tiger shrimp (Penaeus monodon)

Ochratoxin A (OTA) and deoxynivalenol (DON), naturally occurring contaminants of animal feed, have been implicated in several mycotoxicoses in farm livestock but there is little information on their toxicity in aquatic invertebrates. Therefore, in the present study an 8-week feeding trial was conducted on black tiger shrimp (Penaeus monodon) to assess the effects of OTA and DON on growth performance, haemolymph parameters and histopathology of shrimp. Results showed that feed supplemented with DON caused no effect on growth or survival rate of the shrimp. However, shrimps fed DON feed diet with 1,000 ppb showed significantly higher growth performance. No significant difference in total haemocyte counts (THC) was found in shrimp fed mycotoxins-supplemented feed. Feeding high level of OTA (1,000 ppb) caused a decrease in phenoloxidase (PO) activity. Although no histopathological change was observed, decrease in serum alkaline phosphatase (ALP), serum glutamic-oxaloacetic transaminase (SGOT) and serum glutamic-pyruvic transaminase (SGPT) levels in shrimp fed OTA or DON indicated that mycotoxin may impair the functioning of hepatopancreatic cells. Since no adverse effect occurred with the highest levels of OTA and DON (1,000 and 2,000 ppb, respectively) on haemolymph parameters and no residue was detected at the completion of the 8-week feeding period, it can be concluded that shrimp feeds occasionally contaminated with OTA or DON have no negative impact on the shrimp culture industry

Streptococcus iniae infection in cultured Asian sea bass (Lates calcarifer) and red tilapia (Oreochromis sp.) in southern Thailand

Streptococcal infections are becoming an increasing problem in aquaculture and have been reported worldwide in avariety of fish species. Here we describe the isolation and characterization of Streptococcus iniae from Asian sea bass (Latescalcarifer) and red tilapia (Oreochromis sp.) cultured in southern Thailand. Conventional and rapid identification systems,as well as the polymerase chain reaction (PCR), were used to determine that the isolate was S. iniae. The virulence of thisS. iniae was higher in Asian sea bass than in red tilapia, as shown by the 10 day-LD50 in Asian sea bass and red tilapia, being1.08x104 and 1.14x107 CFU, respectively. Histopathological changes in Asian sea bass are more severe than those observedin red tilapia. The changes can be found in several organs including liver, pancreas, heart, eye and brain. Histopathologicalfindings included cellular necrosis, infiltration of lymphocytes and granuloma formation in the infected organs

Gonapodasmius epinepheli observed in cage cultured orange spotted grouper (Epinephelus coioides) in Southern Thailand: geographical distribution of parasite and host response

Gonapodasmius epinepheli Abdul-Salam, Sreelatha & Farah, 1990, a didymozoid trematode, was found in orange spotted grouper (Epinephelus coioides, Hamilton, 1822) cultured in cages in Southern Thailand, both on the east coast (Gulf of Thailand) and the west coast (Indian Ocean). The parasite encysted on the primary lamellae of the gills. Histological sections revealed that larvae were primarily embedded underneath the gill epithelium and eggs of the parasite were distributed in some organs such as gill epithelium, heart and macrophage centers in the head kidney. Pathological changes and host response were shown mainly on gill lamellae, e.g. reduction and destruction of secondary lamellae. Prevalence of parasite and its life cycle are discussed in this report

Mali Boonyaratpalin

198

Mali Boonyaratpalin

198