The rumen anaerobic fungi

Yeasts and aerobic fungi have long been known to be normal inhabitants of the rumen (Clarke and DiMenna, 1961; Sivers, 1962a, b; Lund, 1974) but most species isolated are considered to be transient and non-functional, entering the rumen with the feed. Some aerobic fungi are capable of growth under anaerobic conditions, and Brewer et al. (1972) concluded that Aspergillus fumigatus, Mucor rouxii and Sporormia minima, which are implicated as causative agents in ovine ill-thrift, could survive in the rumen. Two other groups of fungi are now known to occur, one group parasitic upon ciliate protozoa, the other saprophytic on plant tissues.