24 Aug 2020

Rural vet sees grass staggers cow disease spike

4:26 pm on 24 August 2020

Having only recently escaped drought, a mild winter on the Hauraki Plains is now creating a different challenge for farmers; grass staggers.

dairy cows grazing in a field with New Zealand mountain in the distance

Photo: 123RF

Prolonged gentle rain, combined with mild temperatures and very few frosts has resulted in rapid pasture growth in recent weeks.

That means many farms have increased their pasture rotation, exposing the cows to younger grasses which were high in potassium and non-protein nitrogen, and low in magnesium. That's a classic recipe for the condition known as grass staggers.

The metabolic disease is caused by magnesium deficiency in cows and when untreated, results in seizures and death.

A rural vet based near Kopu, Dr Greg Lindsay, from Franklin Vets said in the last fortnight there had been a spike in calls about grass staggers.

Lindsay believed this was a combination of drought, which had lead to cows being a bit lighter at calving and rapid pasture growth, which was prompting farmers to use it as a source of feed more than they usually would this time of year.

"This year it seems to be coming home to bed. So we're seeing multiple deaths and all of a sudden, so it'll be going along fine and then a farmer just gets two dead cows all of a sudden and the majority of those have come back as hypo-mag or low magnesium issues."

Lindsay said farmers who suspected that their stock were at risk should speak to their vet.

"Really just looking at the whole farm system, what's going into the cows? Is it enough to compensate that risk of grass staggers overall?," he said.