Parasite Control Pays Off

Despite the fact that deworming is such an economically sound practice, nearly 40 percent of cow-calf operations only treat their cows once a year.1 While the belief may be that this saves on treatment input costs, choosing not to deworm could, in fact, potentially cost producers as much as $200 per head per grazing season.2

To achieve an optimal return on investment, producers need to take several factors into consideration, including how long a product works and which parasites it treats, timing and pasture management to avoid recontamination of the grazing land.

Joe Dedrickson, DVM, Merial Veterinary Professional Services, says that it is a common misperception that parasite control products protect cattle against parasites for the entire season. “Most products work, on average, 14 to 28 days, depending on the product and the parasite.3,4 White drenches and pastes kill only what is present in the animal at treatment with zero persistency,”5 Dr. Dedrickson says.

Studies show that there needs to be persistent parasite control for at least 100 days to break the parasite life cycle. 6,7 Thus, one fall or spring deworming will simply not provide seasonal protection in your herd or on your pasture and opens up your operation to continual parasite reinfection.2,3

According to a strategic deworming study, timing is also critical to the success of any deworming program. 8 It states that, “It is important not only to treat when cattle are worked, but to time treatments to kill these parasites before they have time to develop into an adult parasite, producing eggs within the animal, which could lead to reinfection.”8

Because every producer’s situation is unique, Dedrickson recommends consulting with your veterinarian when developing a deworming strategy, and suggests keeping the following in mind: “The time of year when grazing season begins, age and category of the animals, type of operation and grazing history of the pasture are all considerations to discuss.”2

For more information about strategic deworming, contact your Merial sales representative.

About Merial

Merial is a world-leading, innovation-driven animal health company, providing a comprehensive range of products to enhance the health, well-being and performance of a wide range of animals. Merial employs approximately 5,600 people and operates in more than 150 countries worldwide. Its 2011 sales were more than $2.8 billion. Merial is a Sanofi Company. For more information, please see

©2012 Merial Limited, Duluth, GA. All rights reserved. RUMIELR1204 (09/12)

1 Parasite Control Practices on U.S. Cow-calf Operations 2007-08. Veterinary Services, Centers for Epidemiology and Animal Health. Available at Accessed July 2, 2012.

2 Miller J. Strategic Deworming. Louisiana State University. Department of Epidemiology. Available at: Accessed January 15, 2012.

3 Arseneau J. Parasite Control. Beef Health Management Course. University of Minnesota Extension Service. Lesson 4.

4 Whittier D, Currin J. Current Strategies in Parasite Control in Virginia Beef Cattle. Virginia Cooperative Extension. 2009. Available at: Accessed March 8, 2012.

5 Label for Benzimidazoles, no persistency claims for GI nematodes.

6 Morley FHW, Donald AD. Farm management and systems of helminth control. Vet Parasitol. 1980;(6.1-6.3):105-134.

7 Brunsdon RV. Principles of helminth control. Vet Parasitol. 1980;(6):185-215.

8 Strategic Deworming is Based on Seasonal Parasitic Contamination Patterns. Mid America Ag Research. Available at: Accessed June 5, 2012.