“…There are a number of factors that can affect an animal's dietary requirement for the vitamin. Adult ruminants and horses can obtain adequate quantities of thiamin from bacteria in the rumen or cecum (Bechdel et al, 1926;McElroy and Gross, 1941;Kon and Porter, 1947;Hotzel and Barnes, 1966;Poe et al, 1972). However, young ruminants between the ages of 2 to 7 months can, under certain circumstances, develop polioencephalomalacia (cerebrocortical necrosis) in which thiamin deficiency plays an essential role (Edwin andJackman, 1981/1982).…”