Residualidade da oxitetraciclina no tecido do camarão marinho Litopenaeus vannamei (Boone, 1931) (Crustacea, Decapoda) submetido a tratamento antibiótico

Abstract

Shrimp culture is a very important economic activity in the world and the fastest growing industry in Northeast Brazil. Problem with diseases are common in aquaculture and at the least seven species of Vibrio bacteria have been registered infecting shrimps during different culture stages. Oxytetracycline (OTC) has been widely used against these pathogens. In this research the distribution and residue depletion of OTC in Litopenaeus vannamei tissue were evaluated after 14 days of exposure to medicated feed containing 4g.kg-1. Two trials were conducted: in indoor tanks under laboratory controlled conditions and in outdoor encrosures installed in a commercial shrimp grow-out pond. Medicated animals were sampled periodically, during treatment period and thereafter. The tissue levels of OTC were measured by hight performance liquid cromatograph-HPLC. Although in both treatments shrimp were similar conditions, OTC peak concentrations were different. After 7 and 12 days off exposure to OTC, residual values in shrimp tissues were 17,21 μg.g-1 and 3,78 μg.g-1 for the laboratory and field studies, respectivally. Mean OTC residual tissue concentration observed both in the laboratory and field trial are within the limits of minimum inibitory concentration (MIC) refered to vibriosis treatment. During the first 72 hours after the treatment ceased drug residues dropped fast, slowing down afterwords. A save residue level of 0,1μg.g-1 following the European Community requirements, were attained at day sixteen of OTC withdrawl. After 25 days of OTC withdraw no drug residues could be detected. However, it is reccommended a longer withdrawl period as a safeward to obtain complet drug depletion.