SURVIVAL OF THE TALL FESCUE ENDOPHYTE IN THE DIGESTIVE-TRACT OF CATTLE AND HORSES

The endophytic fungus of tall fescue, Acremonium coenophialum, is naturally disseminated only by infected seed. Grazing livestock could serve as potential vectors of this fungus, and stockmen could unwittingly encourage its spread by inappropriate movement of animals between pastures. To test this possibility, a series of experiments were conducted in which cattle were fed a single dose or were allowed to graze ad libitum. Viable endophyte-infected (EI) seeds were recovered from the feces. Recovery of live endophyte reached a maximum of 2.68 EI seeds per gram dry weight (gdw) of feces at 22 hr after feeding a single dose. The last viable endophyte was recovered at 38 hr after feeding, and the last viable seed was recovered at 84 hr. When allowed to graze fescue with EI seed ad libitum, cattle feces contained about 1 EI seed per gdw while feeding and continued to pass decreasing amount of EI seed for 72 hr after removal from the infected pasture. Horses allowed to graze ad libitum passed 0.37 EI seed per gdw. Both cattle and horses were effective vectors of the endophyte and may be a significant source of infection when they are allowed to graze seed and moved to endophyte-free pastures without a period of quarantine. A 3-day quarantine period should be sufficient to prevent the spread of EI seed.