Are You Creating Resistant Parasites?

Along with super weeds that are resistant to herbicides, bacteria that no longer succumb to antibiotics, there are parasites that are no longer bothered by worming medication. The problem first began appearing in New Zealand, South Africa and South America, and is now emerging in the United States.  Who's to blame?  We are. But just like the parasites change and become resistant, we can change too.  So here's how we're creating resistant parasites and how we can stop. Always Make Sure You Have Some Parasites Around Any time you treat your livestock with an antiparasitic, there are a few in the bunch that just don't succumb. They become the potential foundation of an entire resistant population of parasites.  Their offspring inherit the resistance gene, they send the resistance on to the next generation, and so on and so on. BUT, if you keep non-resistant parasites in the mix, they dilute the resistant parasites, slowing the development of a fully resistant population. So what you want in your herd or your operation is a "Refugia." A refugia is a place where parasites are not treated, so that they are under no pressure to develop resistance. You can provide "host-based" refugia in untreated animals. Eggs and larvae already on the pasture when you treat animals is an "environmental refugia." Don't Do This We destroy refugia and speed up development of a fully resistant parasite population when we do these things: Treat every animal in the herd.  This increa

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2 thoughts on “Are You Creating Resistant Parasites?

  1. I attribute the increase in parasite resistance in my flock of 100 ewes, with 165% lambs weaned and raised, all on 39 acres, here in southwest Michigan to one thing; An effort on my part, to supply the Full Spectrum of Nutrients.

    Here’s my experience; Three years ago I was doing 2 and 3 wormings per year and still having animals suffering anemia, bottle jaw, with unthrifty wormy lambs, compared to last year I had 17 ewes that looked like they could use a worming in May, and that was IT, no more bottle jaw, and doing good on the famacha score as I would run them through a couple times during the summer. This big a difference on basically the same ewes.

    So what exactly is doing the trick? All I can say is; I don’t know. But my aim is to give the sheep adequate nutrition with an emphasis on micro nutrients. So for starters, rotational grazing of deep rooted, multi-species, perennial pastures, and fertilized with the nutrients that are determined to be lacking. On my property they were Calcium, Sulfur, copper, boron, and cobalt. I also do a significant amount of strategic bale grazing of purchased hay, and wheat midds plus sugarcane molasses, fed on pasture, which also adds to the soil fertility.

    It depends on the season and nutritional needs but a common mineral mix consists of equal amounts of Salt, Diatoms, Kelp, Dynamin, Humates Then I also add the micro-nutrient pack from Pipestone vet. and occasionally some additional COWP’s and cobalt sulfate.

    Supplements like these come with a price tag, but I expect most of them to stay on the farm. And how do you go about figuring the price of using chemical wormers, things like the damage done to dung beetles, earthworms, and birds health. And how do you value the privilege of assuring your customers that your lambs had not been wormed for months before slaughter. Full disclosure; last year I gave all my lambs one dose of valbazen for tapeworm and some of them one dose of cydectin for haemonchus contortus. Best crop of lambs yet and never taken off of pasture. Thanks for all the great articles

  2. I would disagree with dragging pastures, nematodes are relatively immobile over distance, where they’re laid is where they stay, dragging would spread manure around and consequently spread the parasite burden over more area, furthermore the manure is host to beneficial organisms, including dung beetles. Dragging destroys the manure pat were some of the beetle larvae exist. The natural tendency for grazing species is to avoid their own manure, which reduces their exposure to parasites. Cattle avoid grazing the regrowth were there was a manure pat from the previous rotation, sheep however will readily graze this graze, cattle will readily graze where sheep manure (or any other species) regrowth is.

    Additional strategies are harvesting regrowth as stored feeds for future use parasite won’t survive in hay or silage and incorporating condensed tannin forages

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