Biological Responses of Nile tilapia <i>Oreochromis niloticus</i> as Influenced by Dietary Florfenicol

Abstract

Antibiotics are used in the treatment of bacterial diseases in commercial aquaculture. In this study, we the biological responses of Oreochromis niloticus juveniles upon dietary florfenicol (FFC) administration at 15 mg (1×) and 45 mg kg biomass−1 day−1 (3×) for 10 days in terms of feed intake, survival, biomass, hematological, erythro-morphological, serum biochemical, and histopathological aberrations as compared with controls. FFC caused a dose-dependent reduction in feed intake, survival, and biomass, with marked variations in hematology, hematological indices, and erythrocytic cellular and nuclear abnormalities, suggesting its apparent cytotoxic and nucleotoxic effects. The serum biomarkers increased significantly in a dose-dependent manner, except for calcium and chloride, which decreased significantly. The therapeutic dose (1×) group exhibited marked histopathological aberrations, such as renal tubular epithelial degeneration and a widened lumen in the kidney, as well as glycogen-type vacuolation and cytoplasmic degeneration in the liver during the dosing period. The extent of kidney and liver tissue damage was more prominent in the 3× group. The 1× serum biomarker levels became normal, with the exception of alkaline phosphatase, within 3 weeks of suspension of dosing. The recovery of the measured parameters and histopathological and erythro-morphological changes suggested that the therapeutic dietary biological responses induced by FFC are reversible and safe for O. niloticus.

Keywords

• aquaculture
• antibiotics
• biomarkers
• hematological responses
• histopathology
• erythrocytes