Feedback from southern extension officers and producers is indicating that ryegrass staggers may be occurring more this year than normal, exacerbated by current seasonal conditions.
Perennial ryegrass toxicoses, or ryegrass staggers, can be a serious and widespread problem and is caused by toxins that accumulate in the leaf sheaths of perennial ryegrass. The accumulated toxins peak in summer and autumn.
The species at risk are mainly cattle and sheep, but alpacas, deer and horses are also susceptible.
Obvious signs from affected livestock includes staggering, excitable behaviour and over-alertness. In severe cases, animals collapse, convulse or die without any apparent early warning signs.
In horses, the staggers can quickly develop into stiffness in the hind legs resulting in difficulty in getting up or lying down.
Identifying ryegrass staggers
The observable signs of ryegrass staggers typically become visible 7 to 14 days after the stock start grazing the toxic plants. Animals that are not severely affected usually recover a few days after being removed from the toxic pasture. Any livestock that are no longer able to get around will need to be nursed back to health – or, in extreme cases, humanely destroyed.
If you see the signs of ryegrass staggers in your livestock, you should move your animals to a safe paddock promptly. If you are unsure whether another paddock is safe, you should provide extra feed to help buffer the risk of toxins. Hay is much better than silage because the toxin levels can remain high for prolonged periods in silage, whereas in hay the toxins seem to decline significantly over the months after it was cut.
Reducing the risk of ryegrass staggers
The risk of ryegrass staggers is greater when the pasture is ryegrass-dominant and short. If you have ryegrass dominant pastures, where possible rotate your pastures so that the animals don’t graze the pasture right down. If you are short of feed and that strategy is not viable, you may need to consider feedlotting at least your weaners, until the pasture grows and you can avoid grazing the pasture right down.
In the long term, you can reduce the risk of ryegrass staggers by increasing other pasture species. Block grazing techniques can increase the clover content. And you can sow other grasses (cocksfoot, tall fescue, prairie grass, phalaris etc, according to your rainfall, soil type and so on).
Also, varieties of ryegrass with low endophyte or non-toxic endophyte are now available. You may need to consider resowing any paddocks that have caused ryegrass staggers with one of these new varieties.
Please note there is no evidence to support claims made by some that different fertiliser regimes or the application of salt or other additives to the pasture or water supply have any effect on ryegrass staggers. The only “cure” is to remove the livestock from the infected pastures until the toxins dissipate.
Source: Animal Health Australia. If you have any queries about grass staggers, please contact your local vet or Bruce Jackson at DPIPWE on (03) 6777 2115.?