Peramine is an insecticide produced by the ryegrass endophyte. Peramine is believed to be the main alkaloid that gives ryegrass with endophyte its resistance to NZ’s major pasture pests Argentine stem weevil and pasture mealy bug. It is not believed to have any effect on animals.
Peramine is produced by all endophytes except AR37 and U2.
Lolitrem B and ryegrass staggers
Lolitrem B is the alkaloid produced by Standard endophyte, which causes ryegrass staggers in livestock, also known as summer staggers. Ryegrass Without endophyte or NEA2 or AR1 endophyte produce very little or no lolitrem B, so stock grazing these are safe from staggers.
Stock grazing ryegrass with Standard endophyte are most likely to suffer staggers when grazing the base of plants in dry summers or grazing the first green growth following a dry period. This is because lolitrem B is concentrated in the base of the plant (see graph). Lolitrem B is also found in seed heads, so rank seedy pasture can also cause problems.
Staggers is seen as tremoring in mild cases and staggering in more severe cases.
Animals are not usually killed by staggers, but may die through misadventure, such as drowning in streams.
Staggers cause severe management problems, particularly if stock must be regularly handled, e.g. milking cows.
Staggers usually clear up within 1-2 days if stock are given a diet containing no lolitrem B.
Lolitrem B is very stable in hay or silage so care should be taken in purchasing these from Standard endophyte pasture.
NEA2, NEA and Endo5 endophytes produce low levels of ergovaline, which are believed to have little or no effect on animal growth or health. Ergovaline also gives plants some resistance to black beetle, and moderate resistance to root aphid. Animal trials on NEA2 endophyte, which produces levels of ergovaline about 30-60% lower than Standard endophyte, have shown the same lamb growth as those on the same ryegrass Without endophyte. The old Standard endophyte, producing high levels of ergovaline in combination with lolitrem B, reduced animal performance.
In ryegrass with Standard endophyte, the concentration of ergovaline is highest in the plant crown and seed head. Ergovaline increases in spring with rising temperature and seed head development. Levels fall after reproductive growth and rise again in response to moisture stress. To minimise animal health problems keep pastures leafy, and try not to graze into the crown of ryegrass plants in summer.
Janthitrems are alkaloids produced only by AR37 endophyte. AR37 produces no peramine, lolitrem B or ergovaline.
Janthitrem levels follow the seasonal pattern of other alkaloids, low in the winter and high in the summer, and give a wide spectrum of insect resistance. Janthitrems have an effect on animal health, although less than the old Standard endophyte (SE). In AgResearch lamb LWG trials AR37 has usually shown similar LWG to AR1 endophyte, significantly better than SE. AR37 can cause ryegrass staggers in sheep; this can be severe and during these periods LWG will be reduced. In endophyte trials run by DairyNZ no ryegrass staggers have been seen in dairy cows grazing AR37. Over the whole season MS production was similar for AR37 and AR1.
Lolines are alkaloids produced by meadow fescue endophyte (Neotyphodium uncinatum), and give a wide spectrum of insect resistance. They are also transocated to the roots of the plant so can assist in detering root feeding insects. At present no data is available on field performance.