Internal parasites, such as worms and protozoa, are a significant threat to livestock health worldwide. These parasites, which live within the digestive system or other internal organs, can lead to a variety of health issues ranging from malnutrition and poor growth to severe illness and even death. In addition to the direct effects on the animal's well-being, infestations of internal parasites can cause financial losses for farmers by reducing productivity and increasing veterinary costs. Effective management of these parasites requires a combination of strategic deworming, good pasture management practices, and maintaining overall herd health. In this blog post, we will explore the best strategies for controlling internal parasites in livestock and how to implement them for optimal results.

The Impact of Internal Parasites on Livestock Health

Internal parasites, including worms (such as roundworms, tapeworms, and lungworms) and protozoa (such as Eimeria in poultry and Giardia in cattle), can have profound effects on livestock health. These effects include:

  1. Poor Growth and Weight Loss: Parasites consume nutrients that the animal would otherwise absorb, leading to stunted growth, weight loss, and poor body condition.

  2. Decreased Milk Production: Lactating animals, such as cows and goats, can experience a significant drop in milk yield due to internal parasite infestations.

  3. Anemia and Weakness: Blood-sucking parasites, such as Haemonchus worms, can cause anemia, leading to lethargy, weakness, and even death in severe cases.

  4. Diarrhea and Digestive Issues: Many types of internal parasites cause gastrointestinal issues, including diarrhea, bloating, and discomfort.

  5. Impaired Reproductive Performance: Internal parasites can also affect reproductive performance, causing infertility or early abortion in some livestock species.

Common Types of Internal Parasites in Livestock

  1. Worms:
    • Roundworms (Haemonchus spp., Ostertagia spp., Trichostrongylus spp.) are the most common in ruminants like cattle, sheep, and goats.
    • Tapeworms (Moniezia spp.) can infect cattle, sheep, and goats.
    • Lungworms (Dictyocaulus spp.) affect cattle, sheep, and goats and can cause respiratory distress.
  2. Protozoa:
    • Coccidia (Eimeria spp.) are a common cause of gastrointestinal illness in poultry and ruminants, especially in younger animals.
    • Giardia can infect cattle, leading to digestive issues and poor growth.
    • Toxoplasma is a protozoan that can cause reproductive issues in sheep and goats.

Deworming Strategies for Livestock

One of the primary methods for controlling internal parasites is deworming. However, indiscriminate use of dewormers can lead to resistance, reducing the effectiveness of treatments over time. A more strategic approach to deworming is necessary to manage parasites effectively.

1. Fecal Egg Count Monitoring (FEC)

Before deciding on a deworming strategy, it’s essential to monitor the parasite load in livestock. A fecal egg count (FEC) test measures the number of parasite eggs in the animal’s feces, giving farmers an idea of the extent of the infestation. This allows for targeted deworming, reducing unnecessary treatments and helping to slow down resistance development.

Best Practices for FEC Monitoring:

  • Perform FEC tests regularly, especially during peak parasite seasons (typically spring and autumn).
  • Test a representative sample of animals from the herd or flock to get an accurate picture of the parasite load.
  • Use FEC results to determine which animals need treatment, focusing on those with higher parasite counts.

2. Rotation of Deworming Agents

Overuse of the same deworming product can lead to parasite resistance. To prevent this, farmers should rotate dewormers from different classes of drugs. Common dewormer classes include:

  • Benzimidazoles (e.g., albendazole, fenbendazole)
  • Macrocyclic lactones (e.g., ivermectin, doramectin)
  • Levamisole (e.g., levamisole hydrochloride)
  • Amino-acetonitrile derivatives (e.g., monepantel)

Rotation Strategy:

  • Alternate between dewormers from different classes, particularly those that target different life stages of the parasites.
  • Follow manufacturer recommendations for dosage and timing.
  • Avoid using a single deworming class for multiple treatments in a row.

3. Targeted Treatment

Not all animals in a herd or flock will require deworming at the same time. In fact, focusing on high-risk individuals and avoiding blanket treatments can help manage parasite resistance more effectively.

Best Practices for Targeted Deworming:

  • Treat only those animals with a high FEC count or clinical signs of parasitism.
  • Prioritize younger animals, as they are more susceptible to parasitic infections.
  • Treat pregnant or lactating females to prevent transmission of parasites to offspring.

4. Deworming Timing

Timing is crucial when it comes to deworming. The most effective deworming treatments should coincide with the lifecycle of the parasites.

Key Considerations:

  • Deworm in early spring and late autumn when parasitic burden is likely to be highest.
  • Treat animals before they are moved to fresh pastures or after they return to contaminated areas.
  • Deworm animals that have been stressed, such as during weaning or transportation, as stress can exacerbate parasitic infestations.

Pasture Management to Control Internal Parasites

Good pasture management practices are equally as important as deworming when it comes to controlling internal parasites. Proper pasture management helps to break the lifecycle of parasites and reduce reinfestation.

1. Rotational Grazing

Rotational grazing involves dividing pastures into smaller sections and rotating livestock between them. This allows grass in each pasture to regrow while preventing parasite buildup.

Best Practices:

  • Move livestock to fresh pastures every 2-3 weeks, depending on the pasture size and parasite load.
  • Allow pastures to rest for a few weeks before animals return, breaking the parasite lifecycle.
  • Use a “clean” pasture for grazing young or more susceptible animals, such as lambs or calves.

2. Pasture Resting and Renovation

Allowing pastures to rest for several weeks can significantly reduce parasite larvae in the environment. During the rest period, parasite larvae die off, reducing the parasite load when animals return.

Best Practices:

  • Implement a pasture rotation system to allow fields to rest.
  • Over-seed pastures with legumes, which can improve soil health and reduce the growth of parasitic larvae.

3. Manure Management

Parasites often thrive in manure, so effective manure management is crucial in reducing internal parasite exposure.

Best Practices:

  • Remove manure from pastures regularly, especially during periods of high parasite transmission.
  • Compost manure before spreading it back onto fields, as the heat generated during composting kills parasite eggs and larvae.
  • Spread manure evenly across pastures to prevent localized buildup of parasite larvae.

4. Fodder and Feed Management

Feeding livestock high-quality, parasite-resistant forages can help boost their immune system and reduce the severity of parasitic infections.

Best Practices:

  • Ensure a balanced diet that includes adequate fiber, vitamins, and minerals to support overall health and immune function.
  • Avoid overstocking pastures, which can lead to overgrazing and a higher risk of parasite infestation.

Conclusion

Controlling internal parasites in livestock is a multi-faceted approach that requires regular monitoring, strategic deworming, and effective pasture management. By rotating dewormers, implementing targeted treatments, and using good grazing practices, farmers can minimize the impact of internal parasites on livestock health and productivity. The combination of these strategies ensures healthier animals, improved farm profitability, and a reduced risk of parasite resistance. With careful planning and management, internal parasites can be kept under control, allowing farmers to maintain healthy, thriving herds and flocks.