Silymarin enhances the performance of Nile tilapia fed an aflatoxin B1-contaminated diet

Intensive aquaculture consumes high amounts of plant-based feed. Unfortunately, this practice increases the risk of aflatoxin B 1 (AFB 1 ) accumulation in fish tissues, impacting their physiological status. The ability of dietary silymarin to mitigate dietary AFB 1 (122.4 ppb) was investigated for 84 days in eight experimental groups: Sil-0 (control, uncontaminated feed), Sil-0.5 (0.5 g/kg), Sil-1 (1 g/kg), Sil-1.5 (1.5 mg/kg), AFB 1 +Sil-0, AFB 1 +Sil-0.5, AFB 1 +Sil-1, and AFB 1 +Sil-1.5. AFB 1 residue in the fish liver of AFB 1 +Sil-0 was 0.86 ppb, while dietary silymarin decreased the residues in the hepatic tissues of AFB 1 +Sil-0.5, AFB 1 +Sil-1, and AFB 1 +Sil-1.5 to 0.64, 0.37, and 0.22 ppb, respectively. Meanwhile, trace residues were found in muscle tissues regardless of AFB 1 levels. Results showed that dietary AFB 1 caused a decline in growth performance and blood indices (RBCs, WBCs, Hb, PCV, MCV, MCH, and MCHC) as well as a decline in lipid profile and serum proteins TP, ALB, and GLO, indicating malnutrition of Nile tilapia. The liver enzymes AST and ALT were up-regulated in response to dietary AFB 1 . Regarding Streptococcus agalactiae infection, fish that received AFB 1 showed high mortality (MR%) and re-isolation (RI%) rates. It also resulted in a weak response to oxytetracycline (OTC) treatment, with high MR%. These effects partially subsided after receiving dietary silymarin, especially Sil-1 (1 g/kg). It is recommended that AFB 1 residues be monitored periodically before oxytetracycline treatment in case of bacterial infection.