Opening the Gate to Better Returns
The Benefits of Parasite Protection on Pasture
For cows and calves turned out to pasture this spring, many will consume more than grass. A reduction in feed intake, the inability to absorb nutrients, compromised immune systems, weakened response to vaccination and susceptibility to disease from internal parasites lurking in contaminated pastures all elevate costs.
"Despite our cold and sometimes harsh winter climate, it is proven that larvae can survive Canadian winters on pasture," says Dr. Lewis, DVM, Merck Animal Health.
"Many pastures may still be carrying the parasite burden from the previous season."
"These larvae that over-wintered will be available to be ingested next spring and infect the cattle. I caution producers that routine deworming in spring, before turnout and then again in the fall, isn't a guarantee that their pastures will be free from contamination in the spring."
As pastures have been proven to carry 90 to 95 per cent of the total parasite burden in cattle, many parasitologists and veterinarians are now recommending pasture deworming programs during the grazing season to help keep them protected and productive.
"Within six weeks of turnout on pasture, clean cattle will pick up worm larvae through grazing grass, leading to new worm infections – making the grazing season a crucial time for deworming cattle," says Dr. Lewis.
A study by the University of Minnesota¹ using Safe-Guard® (fenbendazole) proved promising returns when it comes to pasture deworming in cow/calf herds. The study performed through two grazing seasons showed that cows on pasture that were provided with Safe-Guard at turnout and again mid-summer, recorded a 94 per cent pregnancy rate compared to cows left untreated at 82 per cent. In addition, treated cows were recorded to produce more milk and their calves were recorded to be 41 pounds heavier at weaning. The Prescription for Effective Parasite Control on Pasture
Dr. Lewis recommends that producers take more of a scientific approach rather than a best guess when it comes to parasite herd health and breaking the parasite life cycle on pasture – one that includes fecal sample testing.
"Figure out what you have first before you treat. Fine tune the treatment with a more scientific approach rather than generalized solutions. A 'treat them all, everything is good approach,' no longer works," says Lewis. "Testing helps us to get a handle on individual herds and then make a strategic plan for effective parasite control."
Dr. Lewis recommends that fresh fecal samples should be taken from pastures before parasite treatment and again two weeks after treatment. These tests are then to be submitted to a veterinarian.
"Eighty per cent of parasites typically reside in 20 per cent of the animals."
Dr. Lewis goes on to say "So you want to ensure that you take enough adequate samples to gauge a true average of parasite load in your herd before treatment then again after pasture turnout. It is also very important that producers watch for resistance through this parasite testing as well. Test results reflecting anything less than a 90 per cent drop in the fecal egg count is considered evidence of resistance. If there are concerns regarding resistance talk to your veterinarian," says Dr. Lewis.
After testing and understanding parasite load or risks of resistance, Dr. Lewis recommends the implementation of a targeted treatment plan at processing, prior to pasture turnout to stop egg shedding back on pasture. "Your pastures may still be carrying the burden from the previous season, but you also want to make sure these cattle don't become a source of pasture contamination for the next season," he continues.
Parasite Control on Pasture
Lewis says that many producers who only treat cattle for parasites in spring and fall miss treating again during late spring grazing – a critical time in the parasite life cycle.
By this time, the cattle have picked up worm eggs from grazing the pasture and parasite treatment will help prevent performance loss and further shedding back out on pasture.
Once on pasture, about six weeks into grazing,
Dr. Lewis recommends deworming cattle on pasture with Safe-Guard, which comes in a pre-mix mineral, which is both odourless and tasteless.
"The most convenient way to deworm cattle once out on pasture, is to use non-handling formulations of Safe-Guard through free choice minerals," says Lewis. "To calculate mineral to Safe-Guard ration, begin by monitoring the cattle's intake of mineral on pasture during weeks leading up to treatment and estimate weight of all animals including calves – proper dosing is 5 milligrams per kilogram of body weight. Then, mix the formulation into the mineral that the herd will consume over a week to 10 days, placing it in a feeder that is protected from elements. It is important to keep in mind that Safe-Guard powder for minerals is considered extra label, so prescriptions will need to be written by your veterinarian."
"Safeguard crumbles are another alternative that can be fed as is, or mixed in some grain. It is best to give it over three days or 1/3 dose per day, to ensure as even consumption as possible. Because it is a half per cent crumble and is fairly bulky, it works really well for smaller herds," says Lewis.
Back at the Chute
"Be sure to watch for parasite load coming off of pasture at the end of the season as well, with follow-up fecal testing, to make a targeted and effective treatment for parasites," advises Lewis.
"If your treatment plan includes the use of a pour-on product, be diligent. Be careful to administer product properly by reading labels and applying pour-on products effectively with a shoulder to tail dispersion. Be attentive to weather conditions as well, as freezing or wet conditions can interfere with product performance. In adverse weather conditions, producers can consider the alternative of an injectable parasitic product rather than pour-on," says Lewis.
Utilizing weight scales or innovative automated device tools like automed®, which offers automated weight-based dosing during processing, will also help avoid the unnecessary costs and resistance risks of over and under dosing.
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¹ Production responses following strategic parasite control in a beef/cow/calf herd, B.E. Stromberg, et. al., Veterinary Pathology 68 (1997) 315-322.