AR37 vs other endophytes

What is endophyte?

An endophyte is a fungus found naturally in many grass species, including ryegrass. It provides the plant with protection from insects, and in return the plant provides the endophyte a place to live and reproduce. Endophytes can only be transmitted from one plant to another by seed. New endophyte strains can be introduced into different ryegrass cultivars, but there is no transmission between adult plants growing in pasture.

Endophytes produce a number of chemical compounds, including various alkaloids. The levels and types of alkaloids produced vary between different endophyte strains. Some alkaloids are toxic or deterrent to particular insects (e.g. peramine and lolines), and some can adversely affect animal health (e.g. lolitrem B1) and may depress animal performance when in high concentrations (e.g. ergovaline2). The key is finding an endophyte that provides excellent pest resistance, while at the same time reduces the risk of compromising stock performance.

Why is AR37 so different?

AR37* is a novel endophyte that produces none of the alkaloids found in other commercially available endophytes. It produces a unique type of alkaloid - epoxy-janthitrems - which have never been found in any other ryegrass/endophyte combination. These epoxy-janthitrems seem to play a role in decreasing insect activity (feeding), while having no adverse effect on animal production, though they may in situations cause ryegrass staggers.

Animal performance and health

For information on the benefits on animal performance and health when using AR37 endophyte click here.

AR37 - DairyNZ Endophyte research

The DairyNZ trial on Scott Farm (Waikato) compared Commando perennial ryegrass-based pastures infected with AR37, AR1, Standard (HE) or without endophyte (nil).

The project aimed to measure ryegrass persistence and pasture yields and to assess any effects of the AR37 endophyte on cow health and milk production.

In the fourth and final milking season white clover was removed to test the effect of endophyte/ryegrass association in isolation from any effect on clover content of pastures. The following bullet points present a summary of results from the four seasons.


Overall conclusions:

  • AR37 ryegrass was clearly more persistent than either AR1 or Standard (HE) ryegrass. This supports findings from previous work.
  • The greater persistency translated into a reduced need for renovation of AR37 pastures after the 2008 drought, but in the three years before that time there was no difference in total pasture yield.
  • There was no sign of ryegrass staggers or any other animal health issues in cows grazing AR1 or AR37 pastures – event at times when cows grazing HE were affected by ryegrass staggers.
  • With ryegrass/white clover pastures, there was a trend for slightly lower milksolids (MS) production over summer from cows grazing AR37 or HE compared with AR1. With pure ryegrass pastures there were no significant differences in MS production. These results suggest that the higher clover content of the AR1 mixed pasture was a contributing factor to the observed MS production differences.
  • Where pasture persistence is the top priority then AR37 will clearly deliver benefits. Where persistence of AR1 ryegrass is not a problem, continuing to sow AR1 is advised. DairyNZ cannot envisage any situation in which farmers should sow HE ryegrass.

*AR37 is protected by patent in New Zealand. 1 Lolitrem B is found in standard endophyte, and is the main cause of ryegrass staggers. 2 Ergovaline is produced by standard endophyte, and by some novel endophytes, but levels vary greatly between cultivars.

 

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