Managing Internal Parasites in Sheep

Internal parasites is the age old topic of sheep that just won't go away.

Here we cover general information on worms and management practices for consideration in order to raise a flock of sheep while diminishing the abundant overuse of chemical de-wormers.

There is no magic bullet for dealing with worms in sheep and management practices vary greatly from region to region and climate to climate.

• The climate where sheep are being raised will play a role. Areas prone to wetness face greater risk than cold and dry areas

• How one is raising sheep will play a role in the risk as well. Raising sheep predominantly indoors will put those animals at an increased risk for worm development. Raising sheep outdoors presents management options for controlling worm load

• Healthy sheep carry internal parasites. The worms are naturally present because there is a symbiotic relationship between worms and sheep. Both receive benefit. Healthy animals will always carry worms but at an appropriate level that does not cause parasitism

• Stress can induce a worm load to over balance the animal

• Rams tend to have less trouble with worms due to them not undergoing stress fluctuations like ewes and lambs

• Animals who ingest small amounts of larvae over long periods are known to become more resistant to worms

• There is greater worm resistance in tropical breeds of sheep

• The general rule of thumb consensus on a worms life cycle is 14 days

• Stagnant muddy water bodies are one of the best hatching grounds for larvae

• Chemical wormers are not the cure to worms. Worms in sheep were never meant to be completely eradicated as we attempt to do on a regular basis with chemical de-wormers

Management Practices for Consideration

If you are in a position of having to treat for worms and seeking information, read about more specific management practices for treating internal parasites.

Quality grass and feed that includes a diverse selection of plants along with a tailored mineral program are probably the two best defenses a rancher has at his fingertips for controlling internal parasite loads.

A healthy ewe equals a healthy lamb. Good body condition and nutrition are key aspects. Healthy ewes will pass on far less worm larvae to lambs thus giving them a good head start.

Avoid diet roller coasters that fatten and thin the ewes throughout the production year. Maintaining good condition requires less energy is less stressful for the animal. Rate the body condition score of individual sheep on a regular basis so you become familiar with scoring and know where your animals are at.

Trouble arises when sheep are not healthy enough to maintain the balance in the rumen that serves to keep worms in check. When the balance swings in favor of the worms, a high worm load results.

The rumen can be altered by feeding too much of inappropriate feeds (ie grains) therefore causing a pH change in the rumen, switching feeds suddenly and/or frequently, lack of minerals and stressful conditions such as crowding or muddy and wet living quarters.

Delay weaning lambs until a later age and consider stress free weaning techniques. Weaning is very stressful to lambs and this is the time many will succumb to worm loads.

Worms live on pasture so a well thought out pasture rotation can prevent ewes and lambs from re-ingesting worm larvae. Moving animals every two weeks and not allowing them to return to a grazed paddock until sufficient time has elapsed can keep the flock ahead of parasites.

Utilizing multi species grazing practices can also provide a break in the parasite cycle as other ruminants serve as a dead end host to the sheep worms thus helping to prevent the spread of larvae. Having poultry follow sheep in the rotation is another way to eliminate a lot of larvae.

Any individual who is serious about moving away from chemical worming drenches and managing worm load in a more natural way will appreciate the book Natural Sheep Care by Pat Coleby. There is a wealth of information in this book regarding mineral supplementation for optimum health of sheep and includes a chapter on managing worms.

One can also look to organic producers for help. These guys have a few clues about how to manage without the chemical wormers and a lot can be learned from their knowledge as well.

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