28 August 1998

Roundworm count high

PASTURE contamination with roundworms is higher than ever this year, reducing lamb growth rates and increasing need for stringent worming.

According to Chris Lewis, Shrewsbury-based sheep specialist, the exceptionally wet year means virtually every worm egg has hatched and survived. "This worm burden, in combination with long grass, means poor lamb growth rates for autumn finishing," he says.

Damage myth

"Its a myth that only mature larvae damage the gut. Developing larvae damage the gut wall. This causes poor growth rates and trace element deficiencies," he adds.

"Worming lambs doesnt give protection for 21 days where they are returned to contaminated pasture, as they will quickly become reinfected.

"It is vital to worm and move lambs to clean or at least fresh pasture. Silage or hay aftermaths will be better, but do not expect them to be totally clean either," stresses Mr Lewis.

"To make the most of wormers, hold lambs six hours without food to clear the rumen. This will allow better wormer absorption.

"Always weigh the heaviest lamb and set the dosage level accordingly. Hold lambs in after worming to flush eggs from the digestive tract and then move to fresh pasture," he says.