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 หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Efficacy of Calcium Hypochlorite on the Prevalence of Microsporidiosis (Thelohania) in Pond-Reared Litopenaeus vannamei) ผู้เขียน: ดร.ชลอ ลิ้มสุวรรณ, รองศาสตราจารย์ , ดร.นิติ ชูเชิด, รองศาสตราจารย์ ,  เกศินี หลายสุทธิสาร สื่อสิ่งพิมพ์:pdf AbstractThe efficacy of calcium hypochlorite for controlling microsporidian (Thelohania or Agmasoma) infection by treating the water before stocking Pacific white shrimp, Litopenaeus vannamei, postlarvae (PL) was studied in intensively cultured ponds. Five ponds (of 4 rai each) were used as the treatment group in which calcium hypochlorite at a concentration of 18 mg/l was added into the ponds while all the aerators were operating. In the control group, no calcium hypochlorite was used. PL10 were stocked at a density of 80 PL/m2 and shrimp were fed with commercial pelleted feed throughout the 120-day culture period. Results showed that the prevalence of microsporidian (Thelohania, Agmasoma) infection of shrimp in the treatment group was significantly lower than that of the control group (P<0.05). At day 50, the average highest percentage of microsporidian infection in the treatment ponds was 5.40% compared with 25.16% in the control ponds. The infected shrimp gradually died off or were eaten by the healthy shrimp so that after harvesting only a few infected shrimp were found. In conclusion, in shrimp culture areas where microsporidian outbreaks previously occurred, calcium hypochlorite at the concentration of 18 mg/l should be used for water treatment before stocking the PL. |
หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : The Effects of Microsporidian (Thelohania) Infection on the Growth and Histopathological Changes in Pond-reared Pacific White Shrimp (Litopenaeus vannamei)) ผู้เขียน:สาธิต ประเสริฐศรี, ดร.ชลอ ลิ้มสุวรรณ, รองศาสตราจารย์, ดร.นิติ ชูเชิด, รองศาสตราจารย์ สื่อสิ่งพิมพ์:pdf AbstractThe effects of microsporidian (Thelohania) infection on the growth and histopathological changes in intensive pond-reared Pacific white shrimp (Litopenaeus vannamei) were studied. Postlarvae 10 (PL10) were stocked at 125 PL/m2 in three earthen ponds of approximately 5 rai (8,000 m2) in an area with a salinity of 30-35 ppt. Shrimp were fed with commercial pelleted feed throughout the 120 days of the culture period. Shrimp were first observed to be infected with microsporidian parasites between 20-25 days after stocking. The highest prevalence of infection between 25-28% was found at day 60 in all growout ponds. Subsequently, the prevalence of infection decreased until the shrimp were harvested at day 120 when only 3-5% of shrimp remained diseased from the three rearing ponds. Shrimp infected in both hepatopancreas and abdominal muscle had the lowest weight, which was significantly different (P<0.05) from shrimp infected in only abdominal muscle and the uninfected group from first sampling at day 45 throughout the 120 days of the culture period. Histopathological changes in diseased shrimp from the hepatopancreas-and-muscle-infected group revealed that white masses of microsporidian parasites had partially infested the hepatopancreas and other organs, including the stomach, lymphoid organ and abdominal striated muscle, while in the muscle-infected group only the striated muscles were partially infested by microsporidians. These results clearly indicated that the severity of microsporidian infection negatively affected the growth and survival of white shrimp. |
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