Is the grass greener?

Paspalum covered in ergot fungus

While we won’t remember this summer for long days at the beach or sunburn, it is remarkable to see green grass at this time of year! Although, along with this green grass, we have noticed an increase in callouts for “wobbly calves”. Below are a couple of the repeat offenders we’ve seen recently:

Paspalum staggers

Paspalum Staggers occurs when cattle ingest the paspalum seed heads infected with an ergot fungus. The fungus initially starts out sticky and green then becomes black when mature, typically occurring under warm, humid conditions. In high enough doses, ingestion of the mature fungus can lead to neurological signs. This is most commonly seen in calves, as due to their smaller size, less needs to be ingested to reach toxic levels. 

Signs may include head shaking, muscle tremors and incoordination – if animals are stressed or overstimulated, they may end-up falling over. Indirect consequences may include dehydration and poor growth rates as animals are unable to graze effectively or make their way to troughs to drink, as well as injury due to misadventure. 

In more extreme cases animals may go down permanently, suffer paddling convulsions, and eventually die. 

There is no specific treatment or antidote for paspalum staggers. In less severe cases, recovery is usually achieved by removing animals from toxic pasture and feeding an alternative feed source such as hay. More severely affected animals may need veterinary attention to initiate supportive therapies such as fluid and anti-inflammatories. 

 Pictured - Paspalum seedhead covered in Ergot fungus

Calf displaying opisthotonos posture

Vitamin B1/Thiamine Deficiency 

Vitamin B1 or Thiamine is required daily by cattle, normally this is produced in the rumen by bacteria. However, in some cases, other types of bacteria that produce thiaminase (thiamine-destroying) enzymes can proliferate within the rumen leading to deficiency. This most commonly occurs when cattle change from a low-quality, high-fibre diet to one containing high carbohydrates i.e. lush pasture. 

A lack of thiamine causes the brain to swell, resulting in signs such as depression, incoordination, blindness, and “star-gazing” and, if allowed to progress, the animal will end up in a characteristic position known as opisthotonos with their head arched backward and legs outstretched prior to death. 

Treatment consists of B1 injections twice daily for at least 3 days. The prognosis depends on the severity of signs. Some animals may end up with permanent brain damage, therefore prevention is better than cure. 

Methods to prevent thiamine deficiency include avoiding sudden changes in diet, particularly if going onto high-quality feed, providing a fibre source when feeding high carbohydrate diets, and supplementing thiamine using an oral drench during risk periods.

Pictured - Calf in opisthotonos position


Franklin Vets

Franklin Vets - excellence in veterinary care for dairy, farming, lifestyle, equine and household pets. BESTPRACTICE ACCREDITED NZ.