| Budget Amount *help |
¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2000: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1999: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1998: ¥600,000 (Direct Cost: ¥600,000)
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| Research Abstract |
The time course of oxytetracycline tissue residues were studied in the kuruma prawn (Penaeus japonicus, 22.9±4.9g). The prawns were kept in tanks with recirculated artificial seawater at a salinity of 22-23‰. The water temperature was adjusted to 25℃. Oxytetracycline was mixed with the diet and orally administered through a catheter to the prawn. The dose of oxytetracycline was 50 mg/kg body weight. At each sample time four prawns were sacrificed and tissues were sampled. Oxytetracycline levels were determined by high-performance liquid chromatography. The recoveries of oxytetracycline from hemolymph muscle and shell were 91.7, 87.5 and 87.3%, respectively. High concentration of oxytetracycline was observed in the order of shell>hemolymph ≧muscle. The elimination half-lives of hemolymph and muscle were 44.7 and 46.8 hours, respectively. The elimination times of hemolymph and muscle were calculated 9.9 and 9.3 days, respectively. However, the elimination half-lives and elimination time of shell could not be calculated because oxytetracycline residues persisted in shell tissues, and the elimination phase could not be recognized until 20 days. It shows that oxytetracycline accumulates in the shell tissues of prawn. Residual oxytetracycline was reduced to 50-70% in muscle by the usual methods of cooking (boiling, baking and frying), whereas reduced levels in shell were only 20-30%. These results confirm that oxytetracycline is more heat stable in shell tissue than in muscle.
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