Milk fever risks concealed in the long grass

But without preventative management in place, the mineral make-up of crops and fast-growing pastures can lead to hypocalcemia, known as milk fever.

Central Tablelands Local Land Services district vet Nigel Gillan said hypocalcemia had been the most prevalent issue in the region during lambing this year.

"It affects ewes in late pregnancy or early lactation," Mr Gillan said.

"Obviously when they're producing milk and growing a fetus, there's a lot of calcium being drawn from the ewe into those resources."

Mr Gillan said ewes could develop hypocalcemia if their normal feed intake was restricted, due to yarding or even bad weather, as well as if their diet was low in calcium.

"Generally the mineral balance of cereal crops or even just a fast growing pasture, leaves them predisposed to hypocalcemia."

He said avoiding handling ewes during late-pregnancy would help prevent hypocalcemia, while if ewes were lambing on grazing cereal crops it was important to provide supplements.

"We often recommend something as simple as a loose lick, with equal parts salt and lime," Mr Gillan said.

"We've had a few cases where a lick has been available and they've still ended up with hypocalcemia, because sometimes rain will crust or damage the lick and that will drop their intake."

Hypocalcemia can be treated with a calcium solution if producers catch the symptoms early.

"A ewe being down and weak is the usual set of symptoms," Mr Gillan said.

"It becomes essentially a paralysis, sometimes there's a muscle tremor, but they're often quite bright, aware of what's going on, they just lack strength to stand.

"It can progress very quickly, sometimes all you will find is dead animals because in just a few hours they can go from being healthy to dying.

"We've seen cases where people get caught out because they've just forgotten to put out the supplement for a couple of days, it unfortunately can bite pretty quickly."