Knowledge is power when dealing with internal parasites
Refugia is a term not commonly heard, but it is the concept of leaving some internal parasites unexposed to a dewormer, essentially giving them refuge. But if you are looking for a practical approach to parasite control, it is something you may want to implement as one of the steps to control parasites in your cow herd. Successfully managing parasites can be done by implementing four practices: diagnostics, combination treatment, refugia and management.
The first step in determining if your herd has a parasite problem is to collect fecal samples. If you feel like your herd is underperforming, you should first decide if it is due to a parasite load. You can’t treat what you don’t know about, so it is a good practice to know what type of worm, if any, you are dealing with.
Combination treatment is the second step if you find you do have a parasite load. Instead of rotating dewormers, the combination treatment utilizes two different classes of de-wormers, which is one of the most effective ways to slow resistance. The three classes of de-wormers are, macrocyclic lactones (endectocides, ex. Ivermectin, Eprinomectin, Moxidectin, etc.), benzimidazoles (white dewormers, ex. Fenbendazole, Albendazole, etc.) and imidazothiazoles (Levamisole). Each class controls a distinct spectrum of parasites, and for a different amount of time.
The third step, Refugia is something that goes against tradition. Sometimes the best choice is to skip the deworming treatment for the entire herd. This leaves a portion of the herd untreated to maintain a population of susceptible parasites, helping dilute resistance across the herd. The strategy would be to only de-worm those with a heavy parasite load and to leave the healthiest animals untreated. Using the fecal egg count from the samples to treat only those that need it.
Pasture management and strategic grazing is the final step to parasite control. Good pasture and nutrition management help keep cattle healthy, which can make them less susceptible to the impacts of parasites. This can help promote a more aggressive approach to refugia programs. If you are de-worming cattle, don’t immediately move them to clean, new pasture since this allows more resistant parasites to survive and reproduce. On the other hand, consider utilizing clean pastures for resistant animals. Moving young, more susceptible animals to clean pastures after they have been treated, rather than moving them to contaminated pastures.
As parasites continue to evolve and become resistant to dewormers, a more strategic approach and “deworming best management practices” need to be looked at and utilized. Knowledge is power when it comes to understanding parasitic worms and dewormers and keeping your heard healthy.
