Ryegrass Staggers

Ryegrass Staggers is a neurological impairment of cattle – particularly of weaned calves and heifers – as well as sheep, deer, horses and alpacas. Horses can be permanently impaired.

It is caused by a naturally occurring ryegrass endophyte (fungus). The fungus produces a toxin that is concentrated in leaf sheaths and seed heads. When ingested the toxin affects the nervous system of grazing animals.

It occurs throughout NZ as far south as Otago, mostly during dry spells (January to late April) when pasture is likely to be in short supply and is being grazed closer to the ground.

Ryegrass Staggers is not the same as grass staggers or hypomagnesemia – a deficiency of magnesium in the blood that can seriously affect cattle.

Symptoms: 

An early sign of ryegrass staggers is that an animal will be unusually anxious when approached. An affected animal will likely show a slight trembling of the head. Skin on the neck, shoulder and flanks will twitch and flicker when the animal is disturbed.

Symptoms progress to head nodding, jerky movements, swaying while standing and staggering movements. A deterioration is evidenced by stiff-legged and jerky movement, short prancing steps and eventual collapse, sometimes with rigid spasms lasting several minutes.

Calves usually remain upright on their briskets with their legs splayed while sheep tend to roll on their sides with head extended and limbs rigid.

• Affected stock cannot be disturbed without risk of their collapse. This makes it difficult to move them to the next feed break or to a yard.
• Affected animals lose physical condition and do not drink sufficient water.
• An immediate economic consequence for dairy farmers is loss of milk production. Affected dairy cows are also at risk of injury when falling in the race and falling on concrete in the dairy shed, yard or milking area.
• Although not fatal in itself, ryegrass staggers can lead to stock losses through ‘misadventure’ – animals staggering into waterways and drowning, falling into an electric fence or other obstacle and being injured, falling down a bank, or into a ditch or swamp and becoming stuck.

Research:

A DSIR test in NZ showed a correlation between the relief of ryegrass staggers and dosing with Epsom salts (magnesium sulphate) and potassium chloride (McColl & Orchard, 1981).

A preventive course of action was indicated in the results of a North Canterbury farm trial with seaweed-based trough treatments for 236 bull calves over a 10-week period (McKenzie, 1985).

Fungicidal spray is an option to suppress potential endophyte build-up in ryegrass pasture.

Long term options for severely affected farms are pasture replacement with an endophyte-resistant grass or livestock replacement with animals bred for ryegrass staggers resistance

Pasture management options aim to:

1. provide fresh breaks into leafy ryegrass where toxicity is naturally lower.
2. provide pasture that has a low endophyte count or is ryegrass-free.
3. provide pasture that includes legumes such as white clover, which dilute toxin uptake.
4. provide ‘safe pasture’ such as lucerne, red clover, chicory, brown top, kikuyu and annual ryegrass (as opposed to perennial ryegrass).
5. make available summer forage crops and supplements such as grain, hay and silage.

Stock management options aim to:

1. leave affected animals mostly undisturbed.
2. move stock slowly and patiently without the stress of bikes, dogs and overcrowding.
3. postpone any non-essential yarding and stock movements.
4. avoid leaving stock in paddocks with natural hazards such as ponds, ditches and bluffs.
5. make allowance for recovering animals now mobile but still lacking normal coordination.
6. implement a weekly drench programme prior to and during the period of risk.

Dairy management options aim to:

1. minimise the distance walked to the dairy yard.
2. milk affected cows only once a day and drench once or twice weekly with a preferred drench formulation that will help reduce the incidence and severity of ryegrass staggers.
3. dry-off badly affected cows to lessen their physical stress.

Vetpack Summer “Tonic” is a mineral-rich, seaweed-based formulation administered to animals as a ready-to-use feed supplement or drench, which is especially formulated for summer feed conditions.� Farmers claim that their on-farm experience with Vetpack Summer Tonic, when used correctly, is that it can greatly assist in reducing the incidence and severity of ryegrass staggers. It is manufactured by Independent Veterinary Supplies Ltd and distributed through Veterinary Clinics to be used as required or as directed by a Veterinary Surgeon

NOTE:

We suggest you take the appropriate action to ensure your animals’ welfare is safeguarded during the period of risk. We also recommend that you consult your local Veterinarian for up-to-date information on ryegrass staggers in your area.

For further information, please contact us