The health and production of sheep grazing
perennial ryegrass with and without wild-type
endophyte (Neotyphodium lolii) has been studied
in several trials over a number of years. Lambs/
hoggets grazing predominantly perennial ryegrass
swards with endophyte developed moderate to
severe ryegrass staggers in summer and autumn,
while those grazing endophyte-free ryegrass did
not. Lambs/hoggets grazing ryegrass with endophyte
also had more dags, lower growth rates, lower
plasma prolactin levels, higher body temperatures
and respiration rates under warm humid conditions.
Most of these adverse responses were more severe
in summer and autumn when endophyte toxin concentrations
were highest. Many of these symptoms
are similar to those described for the “autumn ill
thrift” syndrome in New Zealand.