Endophyte Alkaloids
Ryegrass endophytes produce different alkaloids:
Peramine
Peramine is an alkaloid produced by some ryegrass endophytes. It provides good control of the pasture pests Argentine stem weevil and pasture mealy bug. It is not believed to have any adverse effect on animals.
Lolitrem B and ryegrass staggers
Lolitrem B is the alkaloid produced by some ryegrass endophytes. At high levels it can cause ryegrass staggers in animals, also known as summer staggers. Ryegrasses without endophyte, or with AR1 endophyte produce no lolitrem B, so animals grazing these are safe from staggers.
Animals 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). However, lolitrem B is also found in high levels in seed heads and their stems, so rank seedy pasture can also cause ryegrass staggers problems.
NEA, NEA2 and NEA4 endophytes provide ryegrass staggers free pasture for dairy cows and beef cattle. We have never seen staggers on commercial dairy or beef farms. However, in an extreme situation, (i.e. summer dry where animals are forced to graze very close to the ground, or grazing rank pasture) a level of staggers may be seen with sheep or deer.
Staggers are seen as tremoring in mild cases and staggering in more severe cases. Animals are very rarely killed directly 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. A low level of staggers usually clears up within 1-2 days if stock are given a diet containing no lolitrem B. Severe staggers can affect animals for weeks.
Lolitrem B is very stable in hay or silage so take care purchasing these if made from Standard endophyte pasture.
Ergovaline
Ergovaline helps protect plants against black beetle and root aphid, but high levels of ergovaline (e.g. from Standard endophyte) can in some situations reduce animal performance. NEA, NEA2 and NEA4 endophytes produce low-moderate levels of ergovaline which tests have shown are unlikely to affect animal performance.
The distribution of ergovaline through the plant is different for different endophytes. For NEA and NEA2, ergovaline levels are very low in ryegrass leaves, but are moderate in the plant crown. This has a significant advantage as leaves are the primary diet of stock, whereas the crown of the plant, containing the growing point, needs protection from insect damage.
Animal health trials on NEA2 endophyte in diploid ryegrass have shown the same lamb growth as those on the same ryegrass Without endophyte.
Lamb liveweight gain (LWG) in Lincoln University trials
Trials suggest the ergovaline intake of dairy cows grazing well managed NEA2-based ryegrass pastures is unlikely to affect animal production. A review of animal intake research* showed that ergovaline intakes below 0.03 mg/kg LW0.75/day have never shown any effect on animal performance, with diploid NEA2 pastures testing at this safe level (see graph).
Calculated ergovaline intakes of cows grazing Standard endophyte were almost double NEA2, at which level ergovaline effects could possibly be seen.
In ryegrass the concentration of ergovaline is highest in the plant crown and seed head. Ergovaline increases in summer with rising temperature and seed head development, and in response to moisture stress. To minimise animal health problems keep pastures leafy through late spring, and try not to graze right into the base of pastures in summer. Using other feeds (e.g. summer crops, silage, PKE, grain) greatly reduces the chance of any endophyte issues.
Janthitrem
Janthitrems are alkaloids produced by NEA12 and AR37 endophytes. They produce no peramine, lolitrem B or ergovaline.
Janthitrem levels follow the seasonal pattern of other alkaloids, low in winter and high in summer, and give a wide spectrum of insect resistance. High levels of janthitrems can cause staggers, although this is not as severe as that caused by Standard endophyte (SE)
In lamb LWG trials ryegrasses with NEA12 and AR37 have typically shown similar LWG to AR1 endophyte, significantly better than SE. However NEA12 and AR37 pastures can cause ryegrass staggers in sheep typically in summer dry situations where stock are pushed to eat into the base of pasture; 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. Although on occasion AR37 has been shown to effect milksolids (MS) production, over the whole season MS production has shown as similar for AR37 and AR1.
Lolines
Lolines are alkaloids produced by meadow fescue endophyte (Neotyphodium uncinatum), and give a wide spectrum of insect resistance. They are produced at good levels in meadow fescue plants, but when these endophytes have been put into perennial ryegrass cultivars loline levels are typically much lower.
They are also translocated to the roots of the plant so can assist in deterring root feeding insects.
While meadow fescues with loline producing endophytes have good insect control, they are typically slow to establish, low yielding, and have limited cool season growth.
