The mechanism of action of this group of mycotoxins on the physiological state of ruminants will depend mostly on the type and form of presentation of the toxin when it is ingested. The main aflatoxins studied are B1, B2, G1, G2, M1 and M2; with the first two being of greatest relevance. Aflatoxin B1 and B2 can be hydroxylated and distributed in milk or its derived products. They are even capable of contaminating food inputs such as hay, silage and grains; representing a serious risk for the large number of mammals that supply themselves with these foods (Jiang et al., 2021). The damage caused by aflatoxins can be even more serious when their action is synergistic with that of other metabolites. High concentrations of aflatoxins can be detrimental to the growth, health and production of animals. Furthermore, the immune system can be compromised and several plasma metabolites may be altered in the event of liver dysfunction (Chebutia et al., 2020). In the rumen, the effect of aflatoxins may involve lower microbial activity due to their significant capacity to inhibit the synthesis of DNA and RNA, which decreases the growth and performance of the animals. However, these conditions are only seen in the laboratory. In the natural environment, the rapid degradation and absorption of toxins into the bloodstream mitigate adverse effects at the ruminal level. Therefore, the negative effect of aflatoxins on productive performance is better explained by systemic toxicity, which includes immunosuppression and liver damage, rather than by direct intoxication or injury to the rumen (Jiang et al., 2021).

T2 and HT-2: These two toxins develop in warm and humid environments, preferably in cereal grains and less frequently in silage forages. In ruminants, these toxins are extensively detoxified by the rumen flora, although T-2 toxin has commonly been associated with cases of gastroenteritis, intestinal bleeding, immunosuppression and reproductive pathologies in cattle (Ogunade et al., 2018). 

Deoxynivalenol (DON): Type B trichothecene produced mainly by species of the genus Fusarium. It has two less toxic forms, which are 3-Ac-DON and 15-Ac-DON, which can occur at the same time as the DON and are typically detected at lower concentrations. In ruminants, DON is absorbed at an approximate rate of 7 to 10%, with the ruminal epithelium acting as a protective barrier against its effects. Furthermore, rumen protozoa and certain bacteria are capable of deacetylating and deepoxidizing ingested DON, thereby neutralizing its harmful effects. In dairy cows, it was found that DON disappears after 24 hours of ingestion, with a serum half-life of 4 hours. The ruminal degradation of DON allows the formation of its derivative, called de-epoxy-DON or DOM-1. DOM-1 represents the majority of DON absorbed by the body, with a value of 81 to 93%. DON and its metabolites are excreted in feces and urine (Gallo et al., 2022). At the cellular level, DON has the ability to inhibit protein and nucleic acid synthesis by interfering with ribosomes and affecting cellular kinases. It also interferes with steroidogenesis. This toxin is commonly called vomitotoxin, and in sensitive animals, acute exposure causes gastrointestinal problems such as melena and diarrhea. In chronic conditions, DON can result in weight reduction, growth retardation and adverse effects on the immune and neurological systems (Ogunade et al., 2018).