Getting pasture with AR37 growing on your farm.

AR37 endophyte can have a tremendous effect on the pasture persistence and productivity of your farm, meaning stock should have a better feed supply on offer.

Pasture is one of your most valuable assets, providing the fuel for your stock to perform at their peak. When you regrass make sure you’re making the right investment for your farm by choosing ryegrass with AR37.

Before you start your regrassing, it’s best to talk to your local Agricom or PGG Wrightson Seeds representative or your local seed retailer to get the right advice for your local area. But here are a few key tips for making the most of AR37:

How to establish pastures with AR37

As with new AR1 pastures, all existing ryegrass plants should be removed from the paddock (using spraying and/or ploughing), and old ryegrass seed buried or germinated (following multiple spray applications or cropping) before planting ryegrass with AR37.

Re-establishment of old ryegrass plants will not result in failure but can reduce animal performance (if old ryegrass has standard endophyte), pasture production and possibly persistence.

Regrassing with new ryegrass/endophyte combinations

Pre-sowing management

Perennial ryegrass produces seedheads from late spring (October) until the end of summer (February).

The endophyte grows from the plant base up the stalk of the developing seedhead and into the new seeds as they form at the tip.  Mature seeds containing endophyte detach from the seedhead and fall onto the soil surface.  This process is called natural reseeding.

These seeds germinate after autumn rain and establish a new endophyte-containing plant in the pasture.  This is the only way endophyte can be transferred between plants.  So if the original seed was infected with wild endophyte the new seedling will also be infected with this endophyte.  This is the main way new pastures become contaminated with plants containing wild endophyte.

Spring removal of old pasture by sowing crops such as maize or turnips eliminates natural reseeding over summer/autumn and is the best way to prepare for the autumn sowing of a new ryegrass/endophyte combination.

Dexcel research has shown that haymaking before the sowing of the new pasture was a major source of contamination, resulting in 2500 ryegrass seeds/m2 on the soil surface compared with virtually none following a crop.  On grazed pastures or those grazed and topped, about 400 seeds/ m2 were counted, rising to 750/m2 where silage was made.  The latter situation (assuming all the seeds germinated) provides about 3x the number of plants found in well-established dairy pasture.

Establishment Method

Establishment methods should eliminate all existing ryegrass plants, reduce ryegrass seed numbers on the soil surface, and provide a seedbed that favours the rapid establishment of the new ryegrass/endophyte combination.  Dexcel research recently compared three methods of establishment following five pre-sowing managements (described below) and looked at the success of introducing novel endophytes.

Table 1: Percentage of perennial ryegrass shoots containing novel endophyte, one year after drilling (work by S Bluett, Dexcel, 2003).

† Ryegrass containing novel endophyte was direct drilled in all cases
*  Spray with Roundup® @ 4 l/ha

Spray/cultivation and spray/fallow/spray were far superior to hard grazing and drilling (undersowing) existing pasture, as ways of establishing a strong new pasture free from contamination with plants containing the wild endophyte.

The spray/cultivation method was successful because:

• Existing ryegrass plants were killed by herbicide and/or were buried by ploughing;
• Seeds lying on the soil surface were buried, preventing their germination.

The spray/fallow/spray method was successful because:

• Existing ryegrass plants were killed by two herbicide applications (disturbing dung pats before spraying will assist herbicide contact of all target plants);
• The timing of the second spray was such that significant autumn rain (50-75 mm) had stimulated the germination of surface seed and seed in dung pats.  Plan the first spray for February.

Undersowing after hard-grazing was not successful because:

• Ryegrass plants containing wild endophyte were still present to compete with seedlings containing novel endophyte.
• The new seedlings containing novel endophyte also had to compete with seedlings containing wild endophyte that were produced by natural reseeding of the existing ryegrass plants.

This greatly reduced the impact of the new ryegrass/endophyte combination on animal health and production.

Maintaining the advantages

• Hay made on old pastures contains the wild endophyte and must not be fed out on new pastures.
• During seedhead growth (December to February) allow at least two days between grazings of old and new pastures so seed in dung from the old pasture can be excreted away from the new pasture.

Conclusion

To get the most out of investing in new ryegrass/endophyte combinations, long-term planning is essential.

Spay/cultivation, spray/fallow/spray or growing a crop before the autumn sowing of a new ryegrass/endophyte combination are recommended establishment methods.

Once established, the new pasture must be managed to stop input of seed from the old pasture growing on the remainder of the farm.

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 persitency 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 tend 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.