You’ve probably heard about endophyte in pasture grasses. Nature has created some interesting partnerships - two are now good news for New Zealand livestock farmers.
The able partnership of legumes, like clover, working with Rhizobium bacteria to use atmospheric nitrogen for making nitrate, one of the most essential plant nutrients, is well known. The other important partnership in New Zealand grasslands is between perennial ryegrass and tall fescue and the special endophyte fungi that live inside them.
When present in perennial ryegrass and tall fescue they produce three main toxic compounds – Peramine, Lolitrem B and Ergovaline. Peramine circulates throughout the grass plant and is a “goodie” as it deters some insect pests (especially the Argentine stem weevil) from attacking these grasses.
Lolitrem B is a neurotoxin and a “baddie” – it causes ryegrass staggers in grazing animals. This toxin concentrates in the shoot bases, flowering stems and seeds, especially in summer and autumn, and also persists in hay made from these grasses. The third toxin, Ergovaline, is also bad news as it lowers blood prolactin levels and causes heat stress in livestock, especially those in the warmer regions. Some of these chemicals combine with other as yet unidentified compounds to depress intake and liveweight gain, and can also cause scouring and dags in sheep.
New Zealand scientists have studied the effects of these compounds on animals, and have also identified endophyte types that do not produce Lolitrem B or Ergovaline. These novel endophytes are now becoming available present in seed of some perennial ryegrass and tall fescue cultivars, and this resolves these serious pasture-related animal disorders. Ryegrasses containing AR1 endophyte have been grown widely in recent years, with considerable benefit for livestock, and tall fescue types containing MaxP endophyte are now being sold, showing similar benefits.