Which cattle should I deworm and when?

Best practices for combating internal parasite resistance to dewormers

August 1, 2023

3 Min Read
Which cattle should I deworm and when?
Submitted by Elanco Animal Health

Cattle producers know deworming cattle takes work. With no new molecules to control internal parasites on the horizon, the threat of resistance weighs heavily. To get the most effective results from your deworming program and to also reduce your impact on anthelmintic resistance, we must shift our thinking to managing parasites of economic concern to a level we can live with economically and our cattle can live with physiologically. In other words, mass treatment is not the answer to parasite management.

Evaluation and measurement

The first step in developing a targeted treatment program is understanding what parasites are present. By doing so, you can also determine the effectiveness of your current program. Several tools exist to evaluate parasites, the species present and the effectiveness of a given treatment. These include:

  • Fecal egg counts (FEC).

  • Coproculture: hatching parasite eggs in the lab to identify the species in a given sample.

  • Fecal egg count reduction test (FECRT): the difference in egg counts before and after treatment.

  • Nemabiome sequencing: a PCR panel that describes the parasite species present in a sample.

  • PCRs to detect genes that code for resistance to one or more anthelmintics.

While each of these tools have a place in the process of developing parasite management strategy, they also each have their own strengths and weaknesses. This is where the use of Species-Specific Quantitative Analysis (SSQA) comes in. SSQA is a holistic and innovative approach to parasite management that uses a combination of the tools above to evaluate the need for treatment and potential treatment options including:

  • The estimated relative parasite load using FEC.

  • Parasite species present, which is evaluated by coproculture and/or nemabiome sequencing.

  • Pathologic potential of the species represented.

  • Estimated percent of the population represented by each species within a given herd or production unit.

  • Evaluation of efficacy of previous or current treatment using FECRT.

SSQA is a new way of thinking that’s not only beneficial to your operation and your cattle, but helps combat anthelmintic resistance. The knowledge gained from SSQA can then help us select the right cows to deworm and the best product(s) to use.

Refugia: Selecting the right cattle to deworm

When you know the parasites you are dealing with, you can then evaluate the potential for economic loss and tailor your treatment program based on the parasite load, type of parasites and determining which cows you will deworm.

Refugia is the practice of leaving some cattle untreated. In doing so, we give refuge to the parasite population from experiencing the drug class of dewormer. By reducing parasite exposure to a dewormer, we reduce the risk of resistant worms on the pasture. In essence, we want the untreated cows shedding eggs through their feces that will remain sensitive to the drug class. This can allow for more treatable parasites in youngstock and calves, increasing the effectiveness and ROI of your treatment.

In contrast, treating every animal in the herd with the same product year after year leaves resistant worms left on pasture. This means any eggs shed through feces may have resistant genes, beginning the establishment of resistant parasite populations.

How many animals should you leave untreated? Researchers suggest 10-20% of adult cattle should go untreated.1 It is important to test and understand which cattle can be left untreated. By using SSQA to evaluate the parasites present and implementing refugia for parasite management, not only will your operation benefit economically and your animals, physiologically, but it is also a sustainable approach. It promotes good product stewardship, which preserves the efficacy of available molecules and, in the long run, saves you money.

Learn more about implementing SSQA and refugia into your deworming program by talking with veterinarian or your local Elanco representative.

LEGAL: Elanco and the diagonal bar logo are trademarks of Elanco or its affiliates. ©2023 Elanco or its affiliates. PM-US-23-1322

1Greer A, Van Wyk J, Hamie J, et al. Refugia-based strategies for parasite control in livestock. Vet. Clin. N. Am. - Food Anim. Pract. 2020; 36(1):31-43.

Subscribe to Our Newsletters
BEEF Magazine is the source for beef production, management and market news.

You May Also Like