Dairy NZ

Project Background

The presence of endophyte (a fungus that lives inside perennial ryegrass) is important because it produces compounds that

The AR1 and AR37 endophytes represent improved selections over the naturally occurring endophyte (known variously as wild type, HE or Standard). For herds susceptible to ryegrass staggers or where particular insect pests occur, they offer potential improvements in ryegrass persistence and yield as well as MS production. Previous work at DairyNZ showed that cows grazing AR1 pastures produced 9% more milksolids (MS) than cows grazing standard endophyte.

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

Research Format

The first three years of this project on Scott Farm (Waikato) compared Commando perennial ryegrass-based pastures infected with AR37, AR1, Standard (HE) or without endophyte (Nil). Six, 0.5 ha paddocks/endophyte treatment were established in April 2005 with Tribute white clover. Another six paddocks of Nil pastures (Run-in) were established outside the experimental area providing endophyte-free feed for cows before short intensive grazing or indoor feeding periods.

This project used both indoor and grazing experiments:

• Cows (8-10 per treatment) were fed indoors on pasture harvested from Scott Farm. These experiments were short-term - typically five to seven days of measurements, preceded by a seven day adjustment to treatments after all cows were fed on Nil endophyte ryegrass for five days.
• On Scott Farm separate small herds of nine cows were grazed for most of the season on pastures of the different endophyte types.

Feed allocation in all experiments was based around offering cows the same allowance of the different pastures.

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.

Research Conclusions

1. AR37 ryegrass was clearly more persistent than either AR1 or Standard (HE) ryegrass. This supports findings from previous work.
2. 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.
3. There was no sign of ryegrass staggers or any other animal health issues in cows grazing AR1 or AR37 pastures - even at times when cows grazing HE were affected by ryegrass staggers.
4. With ryegrass/white clover pastures, there was a trend for slightly lower milksolids production over summer from cows grazing AR37 or HE compared with AR1.

Implications for farmers

Where pasture persistence is the top priority then AR37 will clearly deliver benefits.  Where persistence of AR1 ryegrasses is not a problem, continuing to sow AR1 is advised.