Internal parasites are a constant threat to cattle health and productivity, especially for animals grazing on pasture. A well-designed parasite control program (PCP) can significantly reduce losses and boost herd performance. This article outlines key strategies for managing parasites in both beef and dairy operations.
Key Points at a Glance:
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Parasites vary by age, environment, and management system.
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Young cattle are more vulnerable than adults.
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Regular fecal egg counts (FEC) help guide treatment.
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Overuse of dewormers can lead to drug resistance.
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Grazing management plays a big role in parasite control.
Why Parasite Control Matters
Internal parasites such as roundworms, liver flukes, and coccidia can silently reduce productivity through:
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Lower weight gain
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Decreased milk production
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Poor reproduction rates
These “subclinical” effects often go unnoticed but are costly. More visible signs include rough coats, lethargy, and diarrhea.
Understanding the Risks
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Pasture-Grazed Cattle: Higher exposure to parasites, especially in heavily stocked areas.
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Drylot Cattle: Lower parasite burden.
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Calves & Young Stock: More vulnerable due to weaker immunity.
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Mature Cows: Typically more resistant, but may need treatment around calving or early lactation.
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Bulls: Generally more susceptible than cows.
Smart Deworming Strategies
Avoid blanket treatments. Instead, use targeted, strategic deworming:
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Conduct FEC before and after treatment.
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Deworm only the animals that need it.
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Test if your dewormers are still working with a Fecal Egg Count Reduction Test (FECRT).
When to Deworm
| Animal Group | Recommended Deworming Time |
|---|---|
| Mature Cows | ~30 days before calving |
| Calves | At weaning, ~30 days after turnout |
| Heifers/Stockers | Spring & fall |
| Bulls | ~30 days before breeding season |
Grazing Management to Reduce Risk
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Avoid overgrazing: Most larvae live in the bottom 3 inches of grass.
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Rotate pastures: Helps break parasite life cycles.
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Eliminate standing water: Prevents liver fluke spread.
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Drag pastures in dry months: Exposes larvae to sunlight and drying.
Know Your Dewormers
Not all products are created equal, and resistance is growing. Dewormers come in various forms:
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Injectables: Most reliable delivery.
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Pour-ons: Easy but must be applied properly.
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Drenches & Pastes: Effective when animals swallow the full dose.
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Feed Additives: Useful in individual pens; harder to control in group feeding.
Always match the product to the parasite species, life stage (larval or adult), and animal type. Follow meat and milk withdrawal times.
Build a Sustainable Program
To maximize success:
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Use fecal tests regularly.
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Rotate drug classes if resistance is found.
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Work with your vet or extension advisor.
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Tailor strategies to your operation’s needs.
Bottom Line:
An effective parasite control program is not one-size-fits-all. By combining targeted treatments, regular monitoring, good grazing practices, and informed use of dewormers, producers can maintain a healthy, productive herd while minimizing drug resistance and treatment costs.
