The Science Behind Safe Endophytes

The Science Behind Safe Endophytes

For immediate release
With photo from Agriseeds
692 words

Scientists aren’t really supposed to operate on gut instinct.

But that’s exactly what led Lester Fletcher to make one of the biggest discoveries in New Zealand agriculture nearly 30 years ago.

Ask him why he first looked into the relationship between ryegrass endophyte, and ryegrass staggers in livestock, and the answer is simple: “I had a strong feeling about it…”

As it turned out, he was on the money, big time. That ‘strong feeling’ led to years of serious science proving once and for all that the endemic Standard or wild endophyte found in ryegrass pastures all over New Zealand is bad news for animal health.

Today, Lester’s still full time in the endophyte business. With his team at AgResearch Lincoln, he is responsible for all animal testing of new endophytes.

Like any job, it has its moments. “But for years I’ve been more than happy to get up and come to work everyday,” he says.

Why? Because the intricate relationship between this particular plant fungus, its host, and the animals and insects that consume it remains intriguing and far from totally understood, even in a country which is widely held to be a world leader in endophyte research and development.

New Zealand agriculture has already benefited to the tune of millions of dollars from the work of our endophyte researchers.

Approximately 80 per cent of the ryegrass planted every year is now estimated to contain AR1, the first staggers-free endophyte released to the New Zealand market.

Seven years after its launch, it remains the ‘bee’s knees’ in terms of animal performance, Lester says.

That’s because the old Standard endophyte not only causes ryegrass staggers, but is also associated with a whole host of sub-clinical animal health issues which were once generally accepted as normal, if not desirable.

These include things like heat stress, ill thrift, depressed liveweight gain and production, increased dags and flystrike, and behavioural issues.

“We know now from all the trials that animals grazing ryegrass with AR1 endophyte grow faster, produce more, and have better overall health than those on Standard endophyte,” Lester says.

“Since 2000, we’ve tested 22 different ryegrasses with AR1 as part of our animal performance research, using sheep grazing trials. We’ve never seen any adverse affects in terms of animal health. Observations of dairy and beef grazing on farms are the same.”

And it’s not like he and his team are not looking for problems.

“We don’t just take a look-see. It’s not a matter of putting animals on trial pastures and saying they look good. We monitor them very closely. We weigh them repeatedly; we measure factors like heat stress, respiration, and body temperature to make sure we don’t miss any sub-clinical health effects.

“We want to maintain the integrity of the product, and we’ve made a big effort with our science to make sure it stands up.”

So who should use ryegrass with AR1 endophyte, and why?

“If good livestock performance is important to you; you’re in an area where ryegrass staggers and other ryegrass endophyte toxicosis problems are a concern and you want protection against insect pests, this would be a good situation for using AR1.

“It’s not designed for marginal or harsh environments. We’ve seen people putting ryegrass with AR1 into areas where ryegrass itself with wild-type endophyte is highly unlikely to survive. I think people’s expectations have been a bit unrealistic in this regard.

“They expect it to perform better than ryegrass with wild-type endophyte, and that’s led to it being used in some pretty harsh, dry environments to which it is not suited.

“What it is highly suited to is situations were good stock performance is paramount, and insect protection is required.”

Because ryegrass with AR1 endophyte is more palatable than that with Standard or wild-type endophyte, farmers also need to be careful not to over-graze it, Lester says.

“The chemicals in Standard endophyte act as a built-in grazing deterrent. But AR1 ryegrass doesn’t have those chemicals, so there’s nothing to stop animals grazing it right into the ground if you’re a few days late in taking them off the paddock. And that’s not conducive to long-term persistence.”

ENDS

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