10 April 1998

Sheep worm risk high

MILD weather over winter is putting sheep at risk from parasites, particularly worms.

Jenny Anderson, MLC sheep scientist, says the lack of cold weather has failed to kill parasites.

"Vet investigation centres reported deaths caused by the roundworm Haemohchus contortus – Barbers pole worm – as early as December, with nematodirus present in pastures as early as February."

Parasitologist Gordon Graham says January, February and early March born lambs should be wormed now. "These lambs will be at risk from nematodirus – and other worms – as it is particularly wormy weather."

He recommends dosing lambs with a broad spectrum product which is effective against nematodirus and all stages of worms.

"A second dose should be administered in May , the same time that late March-born lambs will require worming."

Before treatment, check weigh sheep and dose in groups of similar sized animals at the weight of the heaviest sheep in the group, says Dr Anderson. "Under-dosing allows some worms to survive, passing on infection and, possibly, resistance to the wormer used. To ensure dose rates are correct, calibrate the dosing gun before use."