Abstract

Adult giant freshwater prawns (Macrobrachium rosenbergii) were fed with practical diets medicated with erythromycin (50 and 100 mg/ kg shrimp for 7 days), while erythromycin residues in their muscle were determined by LC-MS/MS method through TUV Rheinland Aimex Vietnam Co., Ltd. Interpolation of the study’s data, following European Agency for the Evaluation of Medicinal Products Guidelines, gave a withdrawal time of 976°C-days (°C-day_water temperature-days) or 35 days. Our study provides preliminary data for a more prudent use of erythromycin in giant freshwater prawns, suggesting a possible withdrawal time after treatment. However, medication at a dose of 100 mg.kg^-1 prawn body weight.day^-1 for 7 days via feed, shows that erythromycin was derived slightly by erythromycin E (2.09 µg/kg) after 1 day of post-treatment. This biotransformation was kept on derivation of erythromycins (erythromycin E: 5.81 µg/kg, erythromycin F: 3.52 µg/kg) at a safe residue on day 23 of post-treatment.

Key words: Giant freshwater prawns, erythromycin, LC-MS/MS, withdrawal time, biotransformation.