Chemoprevention of aflatoxicosis in poultry by dietary butylated hydroxytoluene

Turkeys are among the most sensitive species to the toxic effects of the mycotoxin aflatoxin B1 (AFB1). The programme reported explored whether dietary antioxidants, which have been shown to exert strong chemopreventive properties against AFB1 bioactivity in mammalian models, are likewise protective in turkeys. The feed of 10-day-old male white turkeys were supplemented with BHT (4000 ppm) for the 20 days of the experiment. At the 10th day of pretreatment, AFB1 (1 ppm) was added to some of the diets for another 10 days to give the following groups: control (no treatment), AFB1-only, AFB1 + BHT, and BHT only. Birds in the AFB1-only group had a lower weight gain, a condition which had returned to near control in groups fed diets containing AFB1 + BHT. Activity of hepatic a microsomal cytochrome P450 (CYP) 1A homologue as well as conversion of AFB1 to the putative toxic metabolite, the exo-AFB1-8,9-epoxide (AFBO) were significantly lower in the BHT group compared to control. Conversely, dietary BHT significantly increased activities of the phase II enzymes glutathione S-transferase, as well as quinone oxidoreductase (QOR). However, there was no observable BHT-related increase in GST-mediated specific conjugation with microsomally-generated AFBO. Dietary AFB1 caused diffuse hepatocellular necrosis and biliary hyperplasia, the severity of which was significantly lessened in the AFB1 + BHT treated group. Slight hepatocellular hydropic degeneration was observed in the BHT-only group, but not in the AFB1 + BHT groups. This condition associated with BHT treatment was found in a separate study to be reversible and without any long-term adverse effects. Despite induction of phase II enzymes in turkey liver, our data indicates that the strong chemopreventive ability of BHT appears to occur via primarily inhibition of AFB1 activation, while having no measurable effect toward specific AFB1 detoxification by GST. Thus, BHT and possibly related phenolic antioxidants may prove to be a viable feed additive for the reduction of aflatoxicosis in poultry.