Ryegrass staggers symptoms
- Tremors in the neck and head (early)
- Heavy tremors and stiff legs (advanced)
Ryegrass staggers symptoms are most likely seen in stock which graze seed heads or graze into the base of the pasture where the endophyte chemical is concentrated. Symptoms start with tremors in the neck and head, followed by heavy tremors and stiff legs. Seriously affected animals often fall over when disturbed. Calves appear to be more susceptible to ryegrass staggers than older stock.
Outbreaks of Ryegrass staggers occur from late November until the end of April, but the problem is sporadic and tends to be worst from late January to early February. Animals are at most risk when a sustained hot, dry spell is followed by rain, especially when pastures are over grazed.
Wild-type endophytes in New Zealand perennial ryegrass pastures produce a toxin that causes ryegrass staggers. Over the past 20 years, new endophytes have become available that do not produce this toxin, while still protecting the plants from disease. Depending on the age of your pasture, and what was sown, will determine the risk of Ryegrass Staggers on your farm.
Preventing ryegrass staggers
Specific management will vary with the farm business goals, pasture type, season and locations. However, some general principles can be used.
The highest levels of endophyte toxins are in the ryegrass leaf sheath, seed head and seed. Management that increases the leaf content of ryegrass and reduces intake of seed head and plant parts near ground level will reduce the chance of ryegrass staggers.
- feeding a high quality supplement (silage, last season's hay, turnips, maize)
- leaving higher post-grazing residuals
- pasture topping or mowing of seed heads
- grazing endophyte-free/low-endophyte/novel-endophyte ryegrass pastures if available (break feed if there is only a small area available)
Supplementary feeding with high quality pasture silage is the most practical way for most dairy farmers to manage ryegrass staggers by substituting supplement for pasture.
Managing stock with ryegrass staggers
Seriously affected stock should be:
- managed separate from the main herd and milking frequency reduced to once a day
- fed a high quality supplement (silage, last season's hay, turnips, maize) to reduce their intake of ryegrass
- fed pasture of another species - tall fescue (not wild), annual ryegrasses, cocksfoot, lucerne, clover or chicory are excellent
- moved slowly and left undisturbed as much as possible
- not grazed in paddocks with hazards; ponds, ditches and bluffs
For badly affected calves consider a 100% supplement diet. Depending on calf weight, 4 kg dry matter per head will be required, some of which may need to be a high quality feed such as meal or brassica crops.