Livestock pharmaceutical company Elanco is urging sheep farmers to carry out faecal egg count (FEC) testing on their sheep before using wormers.

Elanco said FEC tests can inform farmers on whether a wormer is needed, the timing and choice of wormer treatment, and any administration or resistance issues with the worming product most recently used.

Matt Colston, Elanco ruminant technical consultant, said farmers should be testing sheep before they drench to prevent unnecessary stress and loss in growth rates.

“Farmers should be testing sheep before they drench; if you spend the time and effort getting the lambs in when they don’t need to be treated, you’re causing unnecessary stress and therefore loss in growth rates, as well as wasting your own time and money,” he said.

Colston said he advises farmers to carry out mob FEC testing by collecting 15 to 20 fresh samples of dung from a selection of animals within the group.

“Testing is important because we can’t predict from the calendar what’s going to happen with worm burdens,” he said.

“The old practice of worming throughout the summer isn’t right anymore; warm and wet weather encourages worm presence and last year it mostly all happened between August and November.”

FEC testing

Colston said the first FEC test should be taken when lambs have been out and grazing for around three weeks and farmers should follow up by testing every three to four weeks throughout the season.

Farmers should test more often if lambs are showing signs of scouring or not growing as well as expected, he added.

“Even if you haven’t checked to see what worms are present before treatment, it’s always worthwhile checking to see what’s been left behind,” Colston said.

“If your chosen treatment leaves enough worms behind, the lambs’ growth rates will be affected; you can lose half the potential growth rates before there’s any outward sign that there’s anything wrong with the lambs.”

The detection of worms through FEC testing after drenching can indicate potential problems with wormer administration, or wormer resistance, Colston said.

According to Colston, common administration problems include:

  • Underdosing of lambs due to not weighing animals regularly enough, and underestimating their weight;
  • Dosing guns not being calibrated properly;
  • Not taking enough time to administer the wormer, and failing to ensure each animal swallows their dose

“Worms left behind after treatment aren’t necessarily a diagnosis of resistance, but rather an indication that you need to investigate this more closely,” Colston said.

“You need to continue to monitor worm egg counts throughout the season, because there will be different worms present at different times of year, and a wormer that doesn’t work so well today, may work well at a different point the season.

“You should also double check that you’re weighing your animals regularly, so you know their correct weight ranges, and always calibrate your dosing gun properly before using it.”