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Timely topic: April 2015

Tips for preventing internal parasites

Margo Hale & Linda Coffey

If not controlled, internal parasites can cause illness in animals. Symptoms of parasitism include weight loss, loss of appetite, depres­sion, weakness, lagging behind or separating from the flock, and possibly anemia, bottle jaw, or diarrhea.

Livestock producers want to raise healthy animals, and so they may treat the sick animals with dewormers. But that is a temporary fix at best, because unless there is a management change, animals will soon be reinfected. Also, most dewormers are no longer working because the internal parasites have developed resistance to the chemicals.

Katahdin ewes
A strong immune system will help animals resist parasites.

A better approach than relying on dewormers is to prevent illness in the first place. A strong immune system will help an animal resist or tolerate parasites; this strong immune system stems from the following:

In addition to having a strong immune system, livestock need to be protected from consuming too many internal parasites. This is accom­plished through sanitation (clean water tanks and feed troughs) and through pasture management.

Good pasture management can help animals stay healthy in two ways: by reducing exposure to internal parasite larvae and by supporting animal health.

Numerous strategies can reduce exposure:

Sunn Hemp grazing
Annual forage crops can reduce exposure to parasites.

Several strategies provide support:


Three actions help prevent illness:

Further Resources

See ATTRA’s Tools for Managing Internal Parasites in Small Ruminants: Pasture Management for a full discussion of pasture management and the interaction between animals and internal parasites. This publication includes three assessment sheets: pasture, livestock nutrition, and internal parasite management. These assessment sheets can help producers refine their management and improve the health of pastures and animals. Find this publication and many other related ones at www.attra.ncat.org.

See also www.acsrpc.org to find a collection of resources to help manage internal parasites in sheep and goats.
Langston University has a Web-based training manual at www2.luresext.edu/goats/training/QAtoc.html.

Some chapters are especially noteworthy:

This work was supported by the USDA, NIFA Organic Research and Education Initiative (Project No. 2010-51300-21641)

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