Control of regulated and emerging silage mycotoxins

Silage, particularly corn silage, represents one of the major routes of mycotoxin exposure in dairy production systems due to the widespread occurrence of metabolites originating from both field and storage fungi. Although ensiling is intended to preserve forage through anaerobic fermentation, microbiological and biochemical processes occurring before and after harvest and during ensiling, storage, and feed-out, may favor fungal proliferation and mycotoxin accumulation. Consequently, silage should be regarded as a dynamic microbial ecosystem in which regulated and emerging mycotoxins frequently co-occur in complex mixtures. Traditionally, research and regulatory frameworks have focused on a limited group of regulated mycotoxins, including aflatoxins, fumonisins, zearalenone, ochratoxin A, and trichothecenes such as deoxynivalenol and T-2 toxin. However, recent advances in multi-analyte analytical technologies, particularly high-resolution mass spectrometry, have revealed that silage matrices contain a much broader diversity of fungal metabolites than previously recognized, including emerging mycotoxins produced by Fusarium spp. (e.g., enniatins, beauvericin, moniliformin, and fusaric acid) and Penicillium spp. (e.g., mycophenolic acid and roquefortines). This review provides an updated perspective on regulated and emerging mycotoxins in silage-based dairy systems, with emphasis on contamination dynamics along the silage production chain, ecological interactions between fungi and fermentation processes, and current analytical approaches for multi-mycotoxin detection. The review also discusses recent studies questioning the scientific basis of current European Union and US Food and Drug Administration standards for aflatoxin M1 in milk, as well as their broader implications for food security, dairy trade, and milk consumption. Finally, mitigation strategies during ensiling and storage are discussed, highlighting key knowledge gaps and future research priorities for improving feed safety in dairy production systems.