Improving ewe nutrition and breaking from traditional worming routines can address the growing problem of anthelmintic resistance in sheep.

Speaking at the AgriSearch sheep walks earlier this week, sheep consultant Lesley Stubbings suggested that too many sheep farmers follow traditional programmes when worming ewes, typically treating animals pre-tupping, at scanning and mid-season, regardless of the level of worm burden present.

“This has led to over-use of wormers and continues to create problems with anthelmintic resistance. Farmers should be monitoring worm burdens before dosing,” said Stubbings.

To get the most effective cover from worming products, Stubbings maintained that farmers should alternate between worming products every time animals are treated, as repeated use of the same product increases resistance.

Therefore, if sheep have been treated with a white drench, they should receive a yellow or clear wormer at the next treatment. She reminded farmers to draft ewes based on weight and body condition before worming, so that there is less variation in animal groups, before setting the dosing rate to the heaviest animal in each group. With lambs, if worming is required every three weeks, then farmers should be questioning if they are treating animals correctly, or whether there is a resistance problem in their flock, she said.

Nutrition

She added that ewes in good body condition prior to tupping do not necessarily need worming.

“If ewes are in good flesh, then worms are unlikely to be causing the animal any problems, so what are the merits of worming such animals?”

Stubbings suggested the practice of worming ewes prior to tupping relates back to outdated science that is no longer relevant to modern, well-run sheep units.

She added that keeping ewes on good-quality grass and supplementing before and after lambing with additional energy will ensure ewes remain in good body condition and become better equipped to handle worm burdens, compared with thinner ewes under nutritional stress.

Reduced use

Referring to host farmer Isaac Crilly, Stubbings outlined how using faecal egg counting and maintaining good body condition on ewes has reduced the use of anthelmintic wormers to around one-third of their previous use.

Read more

Nearly 50% failure rate in sheep dosing

Avoiding anthelmintic resistance on sheep farms