Magnesium deficiency in pastures leading to stock deaths

That solid pasture growth is certainly welcome and no farmer of any description is going to knock it back, but when the conditions aren't conducive to clover growth, the impact on cattle, particular lactating or heavily pregnant cows, can be fatal.

Clover is a richer source of magnesium than the grasses and when the conditions aren't suitable for good clover growth, such as the weeks of overcast, drizzly conditions we've experienced this winter, the pasture gets away nicely, but the clover doesn't.

Local Land Services Regional Veterinarian Bruce Watt said that the problem of magnesium deficiency is particularly an issue for cows.

"Cows need a lot of magnesium to make milk," he said. "When they're on pastures like this they simply don't get enough of it as it's going out in the milk but not coming back in the feed."

Mr Watts said that the cows develop serious problems when they become deficient in magnesium.

"It causes cows to develop convulsions and they can collapse and die," he said.

Known as Grass Tetany the condition is highly prevalent across the central tablelands at present and for Errowanbang grazier Stuart Grant the issue hasn't been around for quite some time.

"We haven't lost a cow to Grass Tetany for well over ten years," he said.

In an average year Autumn and Winter rains bring on a flush of clover, which if consumed in large quantities causes bloat in stock.

"I think we're coming to the end of it now though, the stock really do bounce when that sunshine comes through."

Mark Richardson from Green's Rural Service Centre in Mandurama, who has lost four of his own cows to the condition, said that the availability of magnesium supplements has proven to be a lifesaver for many cows.

"There has been a massive uptake in the sale of supplements to the point where it's very difficult to source," he said.

Getting the cattle to eat it though is difficult when there is just so much grass about.

"There are loose licks available or you can try by putting hay out and adding magnesium sulphate to that," he said.

He also added that the condition was starting to move eastward.

"I've had a lot of calls from people out towards Neville looking for magnesium supplements."

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