Impacts of florfenicol on immunity, antioxidant activity, and histopathology of Oreochromis niloticus: a potential protective effect of dietary spirulina platensis.

The misuse of antibiotics enhances the development of resistant microorganisms and decreases the efficacy of treatments. Florfenicol (FF) is one of the antibiotics approved for use in aquaculture in Egypt. Because of its extensive usage, potential negative impacts on aquatic creatures are a major concern. This motivates us to search for an appropriate neoadjuvant to work synergistically with FF and reduce adverse effects. Results from this study will contribute towards improving the understanding of the impacts of FF on Oreochromis niloticus and the possible amelioratory effects of Spirulina platensis algae (SP). O. niloticus (n = 240; 40 ± 2.5 g) were fed on two diets supplemented with or without SP for 4 weeks, then divided into four treatments each in three replicates (n = 60/treatment). G1; was fed a control diet, and the other groups were fed diets supplemented with FF (10 mg /kg of BW, G2), SP (2 g/kg of diet, G3), or FF + SP (G4) for 10 days. Among the four groups, the SP group (G3) had the best immunostimulatory effects as observed by a significant (p < 0.05) elevation in phagocytic activity, phagocytic index, IL6, and TNF-α. The treatment with FF had significantly impacted hepatic and renal tissues, as the values of liver enzymes and creatinine demonstrated tissue deterioration and also resulted in oxidative stress, which was expressed by an increase of GPx, CAT, and SOD in (G2). Additionally, the combined FF + SP improved the hematological parameters and decreased the oxidative damage induced by FF (G4). Thus, it was clear that FF has harmful effects on O. niloticus and that SP can modulate such impacts. These data recommend the use of SP as an effective immunostimulant and a probable adjuvant to FF in O. niloticus diets to attain maximum disease resistance.