Dynamics impacts of oxytetracycline on growth performance, intestinal health and antibiotic residue of grouper in exposure and withdrawal treatment

Little is known about the effects of oxytetracycline (OTC) on marine fish. Using juvenile pearl gentian grouper (Epinephelus fuscoguttatus female x E. lanceolatus male), we investigated the effects of 56 days dietary oxytetracycline (OTC; OTCD) exposure (80 mg/kg body weight/day) on fish growth performance, intestinal health and antibiotic residue. Meanwhile, the alteration of intestinal health status and antibiotic residue after 7 (O7) or 14 days (O14) OTC withdrawal treatment were explored. We also assessed the potential human health risks based on target hazard quotient (THQ). The results showed that OTC exposure had no effects on growth rate parameters but caused liver and intestine atrophy. OTC exposure impaired the intestinal health by distorting intestinal morphological features, inducing oxidative stress, repressing immune function, triggering NF-kappa B-mediated in-flammatory response and apoptosis, while 7 days OTC withdrawal treatment improved intestinal health status and 14 days OTC withdrawal treatment further improved it. In addition, the order of OTC residue in tested tissues after OTC exposure was: liver > kidney > spleen > muscle > intestine. OTC residue was significantly decreased in all tissues along with the increasing of withdrawal treatment period. Adults and children consuming the edible tissues (muscle) of OTC-treated or withdrawal-treated pearl gentian grouper would not experience any previous health risk as the THQ < 1 in all group.

Automated summary

This study investigated the effects of oxytetracycline (OTC) on marine fish and its impact on intestinal health and antibiotic residue. The results showed that OTC exposure had no significant effects on fish growth, but caused liver and intestine atrophy. OTC exposure also impaired intestinal health and induced oxidative stress, inflammation, and apoptosis. However, withdrawal treatment improved intestinal health status. OTC residue was found mainly in the liver, kidney, and spleen, and decreased with withdrawal treatment. The consumption of OTC-treated or withdrawal-treated pearl gentian grouper muscle posed no significant health risks according to the target hazard quotient assessment.