Evaluation of the effect of BHT and MOS on volatile fatty acid production and microbial count in vitro for aflatoxin risk mitigation

Aflatoxin B1 (AFB1) contamination of ruminant feeds adversely affects rumen microbial ecology and fermentation, leading to reduced nutrient utilization. The present in vitro study evaluated the efficacy of two detoxifying agents, butylated hydroxytoluene (BHT) and mannanoligosaccharides (MOS), in mitigating the adverse effects of AFB1 on total volatile fatty acid (TVFA) production and rumen microbial populations. A total mixed ration (TMR) was contaminated with AFB1 at 31 ppb and supplemented with BHT or MOS at 0.05, 0.10, and 0.20% inclusion levels. In vitro incubation was carried out using rumen liquor obtained from a fistulated donor animal, following the gas production technique. Results showed that BHT supplementation caused only marginal and biologically insignificant changes in TVFA concentration and microbial counts, indicating limited efficacy under aflatoxin challenge. In contrast, MOS supplementation significantly increased TVFA concentration as well as bacterial and protozoal populations in a dose- dependent manner, with the most pronounced response observed at the 0.10% inclusion level. The improved fermentation with MOS is attributed to its dual role as a mycotoxin binder and prebiotic. The study concludes that biological detoxifying agents, such as MOS, are more effective than chemical antioxidants in alleviating aflatoxin-induced impairment of rumen fermentation.