Paper presented at the 56th New Zealand Grassland Association Conference, 17-20 October 1994, Hanmer Springs.Endophytes in perennial ryegrass protect their hosts
against attack by Argentine stem weevil but cause
adverse affects, including heat stress, in grazing
animals. Ten lambs were grazed on Grasslands
Nui ryegrass without endophyte or with its wildtype
or a high ergovaline-producing endophyte
(196). Five lambs from the 196 treatment were
swapped for 5 on the endophyte-free treatment
after 20 days. Rectal temperatures and respiration
rates were measured daily; on one day they were
measured every 2-4 hours. There was a significant
difference in respiration rate and body temperature
between lambs grazing endophyte and endophyte free
treatments but not between the two endophyte
treatments. There was no interaction with ambient
temperature within the range 12-30°C. When
lambs where transferred from toxic to non-toxic
treatments there was no significant decrease in
body temperature or respiration rate witbin 14 days.
Ergovaline, even at low concentrations, affects
thermo-regulation in lambs and is undesirable in
perennial ryegrass endophyte associations.Meat Research and Development Council
