Abstract:

Oxytetracycline (OTC) residue in Nile tilapia Tilapia niloticus muscle was assayed after injection and oral administration. The OTC concentration in fed fish was the greatest after 10 d of feeding medicated feed, and was 0.46 and 0.14 µg•g^-1 in the 75 and 50 mg OTC•kg^-1 treatments, respectively. The OTC residue was below a detectable level in fish fed 50 mg•kg^-1 10 d after treatment, and in fish fed 75 mg OTC•kg^-1 15 d after cessation of medicated feed. The β-value and half-life (t1/2) were 0.1642 d^-1 and 4.2 d, respectively, for 50 mg•kg^-1 fed fish; and 0.1759 d-1 and 4.0 d, respectively for 75 mg•kg^-1 fed fish. Muscle OTC concentration was higher in fish receiving an intraperitonal (IP) injection than in fish fed OTC. The OTC residue decreased from 7.56 µg•g^-1 on the first day to 0.58 µg•g^-1 on day 10 after injection for 163-mm fish, and from 5.83 to 0.27 µg•g^-1 for 229-mm fish. Muscle OTC concentration was not detected in IP-injected fish 20 d after treatment in the samples of both size fish at 23.4ºC. The β-value and t1/2 were 0.2687 d^-1 and 2.6 s for OTC-injected 163-mm fish, and 0.2554 d^-1 and 2.7 d for 229-mm fish. There was no significant difference and liver of fish fed at rate of 1.5 and 3.0% body weight was significantly lower than fish receiving no feed.

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Date 1995/10/01

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