Farmers are being warned to potentially test their dairy herds for phosphorus deficiency, which can often be spotted by cows licking stones.

The dry weather in April decreased the ability of pasture to uptake phosphorus and the Department of Agriculture has issued a stark warning on the subject.

It said that out of 73 blood tests in Athlone regional veterinary laboratory in April, some 47% had inorganic phosphorus values that were low or below the normal range.

Phosphorus deficiency in cows is associated with weakness, decreased milk yield, haemoglobinuria and ‘pica’ or depraved appetite.

Affected cows can often be seen trying to lick stones.

Farmers who suspect their herds might be affected should contact their vets and conduct blood tests.