Clarification on milksolids production from AR37

Clarification on milksolids production from AR37 ryegrass

On the 20th March 2008, DairyNZ released a press release on its trial with AR37 ryegrass. In reviewing this release with Grasslanz Technology, DairyNZ and Grasslanz Technology have collaborated to add some information to the initial release. This information is seen as providing important aspects for consideration by farmers undertaking pasture renewal.

In the one complete season of a planned three-year DairyNZ Waikato trial available so far the annual milksolids results show no significant difference in milksolids production on a per cow basis from AR37 pastures compared to AR1 pastures. However in three grazing trials and two indoor feeding trials there are seasonal differences with the summer/autumn results showing statistically significantly more milksolids for AR1 over AR37 pastures. In early March the AR37 pastures had double the tiller density of other treatments, but the drought continues. Other evidence shows that over time AR37 pastures persist longer and produce more dry matter relative to both standard endophyte and AR1 pastures.

No cows in the DairyNZ trial showed signs of grass staggers when fed AR1 or AR37 pasture.

Generic Ryegrass Information

• New Zealand milk production is largely based on grazing ryegrasses
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• Ryegrasses are susceptible to many insect pests
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• Perennial ryegrasses have evolved a symbiotic relationship with fungal endophytes
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• The standard wild type (HE) strain confers some insect pest resistance but the protective alkaloids have some toxicity for cattle leading to reductions in milksolids and ryegrass staggers
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• The AR1 endophyte strain, available commercially in several grass varieties, has a different alkaloid content, produces more milksolids than standard endophyte, but has a narrow range of protection against insect pests
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• AR1 was developed to combat negative animal performance and health issues associated with standard endophyte e.g. heat stress and ryegrass staggers
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• The AR37 endophyte, available in four grass varieties, has a much broader insect pest protection and has shown higher dry matter production in nationwide trials.
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Our advice to farmers intending to sow ryegrass, based on all the knowledge we have, is:

1. Choose a novel endophyte, not Wild Type or HE when sowing any endophyte-ryegrass combination.
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3. AR37 does seem to produce less milksolids from the same pasture yield compared with AR1. However there is evidence that AR37 will persist and yield more dry matter than AR1 over the medium term.
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5. Where persistence of AR1 ryegrass is a problem, then sowing AR37 ryegrass is the best option.
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7. Where AR1 persistence is good, farmers should continue to sow AR1 ryegrasses.
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