Dietary supplementation of Terramycin and Romet-30 does not enhance growth of channel catfish but does influence tissue residues

Abstract

Two controlled feeding trials were conducted in which Terramycin and/or Romet-30 were incorporated into either semipurified or practical diets to provide 25, 50 and 100% of the recommended dosages when fed to juvenile channel catfish at 3% of body weight per day. Data for 4-wk and 8-wk weight gain, feed efficiency, and survival of channel catfish fed the various diets were analyzed to determine if these responses could be enhanced by dietary inclusion of either or both antibiotics. In addition, 4-wk and 8-wk muscle samples from fish of each dietary treatment were analyzed by high performance liquid chromatography for oxytetracycline (OTC), ormetoprim (OMP) and sulfadimethoxine (SDM) residues. The performance of juvenile channel catfish was not enhanced by the inclusion of Romet-30 or Terramycin in semipurified or practical diets. Moreover, fish performance tended to decrease relative to that of fish fed the control diet when antibiotics were supplemented in the diet. Residues of OTC, OMP and SDM in the fillets of catfish fed medicated diets generally increased in a time- and dose-dependent fashion. Residue concentrations above the legal tolerance limit of 0.1 mg/kg were noted in most samples from fish fed diets medicated at 100% of recommended levels and in many of the samples from fish subjected to lesser dosages, particularly in those that had been fed diets with Romet-30. Allowing catfish that were previously fed medicated diets a 3-wk or 4-wk withdrawal period effectively decreased the OTC, OMP and SDM contents of fillets to undetectable levels.