Reduce worm resistance using faecal worm egg counts

Reduce worm resistance using faecal worm egg counts

With spring finally here and the weather warming up, it is important to worm cattle and sheep effectively as we head into summer. With increasing resistance to wormers reported across the industry, we wanted to highlight the value of regular faecal worm egg counts. (A reminder that this is also part of the Animal Health and Welfare Review funding!)

Firstly, it is important to test if worming is required by carrying out regular faecal samples from at least 10 animals. Your vet can then perform a Faecal Egg Count (FEC) before you worm your animals to identify if they need worming and which wormer would be most appropriate. It is very beneficial to send in a follow-up sample 14 days post worming; except if you have used a wormer from the yellow group, “levamisoles” which is 7 days post worming. If this “post-worming” FEC does not show a 95% reduction of worm eggs, then there may be a resistance problem in your flock or herd. Your vet will be able to advise you on the most effective and appropriate worming plan for your farm using your results.

Resistance is a big problem.

Wormer resistance is the loss of sensitivity to a treatment in a worm population that was previously sensitive to the treatment / active ingredients. This resistance is passed on through generations of worms, as a genetic trait, so once it is on your farm it is likely there to stay. It’s important to note, that it’s not your livestock that have generated resistance, it’s the parasites themselves. Bearing this in mind, a parasite control strategy based wholly around wormers is not sustainable – they are important products and so, just like antibiotics, need to be used with care so that we have them to use in essential situations.

In the sheep industry, resistance to the 1-BZ (white), 2-LV (yellow) and 3-ML (clear) group is increasing rapidly. Many wormers are not used effectively, because they are either given incorrectly, such as underdosing or by the wrong route. Under-dosing speeds up the development of resistance and wastes huge amounts of time and money as well as not effectively treating the animals.

In many cases, farms who use FECs to monitor worm burdens use less anthelmintic without any loss in performance saving money and withdrawal periods. If you know which worms you have on the farm you can target them more effectively and with the most appropriate product. This significantly reduces the chances of developing resistance on your farm.

Speak to your vet to discuss the benefits of faecal egg counting and how it would work best for your system to reduce your risk of building up resistance.

Posted by Alison Eves
1st March 2023

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