Cattle grazing on pastures are inevitably exposed to internal parasites that can lead to significant production losses and health issues. While complete confinement may minimize parasite exposure, managing parasites is an ongoing challenge for cattle exposed to pasture environments. Control of internal parasites can be achieved through the use of various oral, injectable, or pour-on products available on the market. However, too often, decisions to deworm cattle are based on their visible symptoms. By the time parasitism is apparent, the damage—both economically and in terms of animal health—has already occurred. The challenge lies in determining when and how often to deworm cattle to minimize exposure and prevent re-infection.
Strategic deworming is crucial for maintaining the health of grazing cattle and preventing parasite-related losses. Effective control relies not only on treating the animals but also on managing the pasture where they graze. Here’s what you need to know to develop an effective parasite control plan.
Key Considerations for Effective Parasite Control:
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Parasite Survival and Spread:
Worm larvae can survive through the winter, remaining infectious until late spring. Warm, wet weather enhances the viability of these larvae, and in the spring, pasture worm larvae populations can be high, leading to disease outbreaks in cattle. Once ingested, these larvae mature into adult worms, which lay eggs that are expelled in feces, further contaminating the pasture. -
Re-infection and Health Risks:
Worms such as Ostertagia can encyst in the walls of the abomasum, then flood the intestines with larvae, leading to serious health concerns. As infected cows graze, they release larvae that can infect calves—who are particularly vulnerable to the harmful effects of parasites.
Goals for Parasite Control:
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Maintain “Parasite-Safe” Pastures:
Reducing contamination on pastures is a priority for minimizing re-infection. To achieve this, it’s important to treat both the animals and the environment. -
Deworming Strategy:
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Before grazing: Administer dewormers to kill adult worms before cattle begin grazing.
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Before egg shedding: Treat cattle to kill immature worms before they can mature and start laying eggs.
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End of grazing season: Deworm cattle at the end of the grazing season to prevent the carry-over of worms. Products that work after the first frost can also eliminate external parasites.
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Young Animals:
Calves are more susceptible to worm infections, so they should be treated three to four weeks after turnout. Subsequent treatments should occur every three to four weeks to prevent maturation and egg shedding of parasites. -
Pasture Management:
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Grazing pressure: The number of cattle grazing a pasture directly impacts the level of parasite contamination. The higher the grazing pressure, the greater the need for a strong parasite control plan.
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Pasture management practices: Techniques like dragging pastures to break up and dry fecal pats can help reduce the number of larvae in the environment.
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Consulting with a Veterinarian:
To optimize parasite control, it’s essential to work with a veterinarian to select the right products for the specific time periods when deworming is needed. Additionally, veterinarians can advise on aligning deworming treatments with other cattle management practices, such as vaccinations and pregnancy examinations, for maximum efficiency.
Effective parasite management is not just about treating cattle but also about managing the pasture and understanding seasonal patterns. By strategically implementing deworming treatments, maintaining clean pastures, and consulting with your veterinarian, you can safeguard the health of your cattle and protect your bottom line from the damaging effects of parasitism.
