Evaluation of the effect of BHT and MOS on digestibility and gas production in vitro for aflatoxin risk mitigation

Aflatoxin B1 (AFB1) contamination of ruminant feeds adversely affects rumen microbial activity, leading to impaired digestibility and fermentation efficiency. The present in vitro study evaluated the efficacy of two aflatoxin-detoxifying agents, butylated hydroxytoluene (BHT) and mannanoligosaccharides (MOS), in mitigating the negative effects of AFB1 on rumen digestibility and gas production. A total mixed ration (TMR) was contaminated with AFB1 at 31 ppb and supplemented with BHT or MOS at 0.05, 0.10 and 0.2% inclusion levels. In vitro incubation was conducted using rumen liquor collected from a fistulated donor animal, following the gas production technique. Results indicated that BHT supplementation did not significantly influence in vitro dry matter degradability (IVDMD) or total gas production, suggesting limited efficacy of antioxidant supplementation under aflatoxin challenge. In contrast, MOS supplementation significantly improved IVDMD and gas production in a dose-dependent manner, with the optimum response observed at the 0.10% inclusion level. The superior efficacy of MOS is attributed to its dual role as a mycotoxin binder and prebiotic, reducing aflatoxin bioavailability while enhancing rumen microbial activity. The study concludes that biological detoxifying agents such as MOS are more effective than chemical antioxidants in alleviating aflatoxin-induced impairment of rumen fermentation.