Animal Safety and Production

Pastures with AR37 produce more drymatter and through better persistence, pasture quality should be higher meaning stock have a better feed supply on offer. With its improved persistence, the risk of feed deficits should also be reduced. Across Australia and New Zealand, ryegrass with AR37 provides the ideal option for superior pastures, where ryegrass pastures with current endophyte options struggle against insect and weed invasion.

Ryegrass with AR37 has been tested by AgResearch for liveweight gain in sheep, and animal performance was the same as ryegrass without endophyte, and AR1 ryegrass. Sheep performance is considerably better with AR37 than standard endophyte. The incidence of dags is as low with AR1.

Growth rates of lambs grazing various endophyte type ryegrasses
(Mean of 3 years)

Standard endophyte association grams/day AR37 association grams/day Endophyte free ryegrass grams/day
44 129 131

Although AR37 can cause ryegrass staggers. Trials have shown that on average the frequency, duration and severity of ryegrass staggers is less than for standard endophyte. However on occasions, sheep (and potentially other animals) grazing AR37 ryegrass may be severely affected.

After many years of use on commercial dairy farms, ryegrass staggers have not been observed in dairy cows on-farm to date.

AR37 varieties should not be used on properties grazing either deer or horses.

Another key benefit of AR37 is that it does not cause heat stress or flystrike, which can be associated with other endophytes that hold high levels of ergovaline.

*AR37 is only recommended for sheep, beef and dairy livestock.

Endophyte Animal Safety
(Ryegrass, Festulolium and Continental Tall Fescue)

The information in this table is based on animal safety trialling protocols designed to expose animals to simulated worst-case scenario management. This involves forcing them to graze deep into the base of pure perennial ryegrass pastures that have been allowed to grow for several weeks over late spring/summer (similar to a hay crop) where they will encounter the highest concentrations of harmful endophyte chemicals if these are present.

This management does not represent normal farm practice although similar situations may arise on farms in in rare circumstances. Under normal farm grazing practices, the contribution of basal pasture material to total animal dry matter intake is relatively low and therefore the intake of harmful chemicals (if they are present) is diluted. Thus, the likelihood of adverse effects on animals is reduced, but the potential for problems to occur may still exist if the endophyte brand is rated < 4-star for ‘freedom from staggers’ and/or there are comments on animal performance which flag potential issues.

Comments on animal performance have been moderated based on information from other trials (in addition to the formal animal safety testing protocols), consideration of the ‘normal’ grazing management practices implemented on farm (see previous paragraph), and recognition that animal diets are very seldom pure ryegrass. Other dietary components such as clovers or non-ryegrass grass species, crops or supplements will dilute the intake of endophyte alkaloids.

This table has been approved by the New Zealand Plant Breeding and Research Association (NZPBRA). These ratings are indicative. Animal performance and health can vary under different management systems and between seasons.