Diatomaceous Earth (DE)
Diatomaceous earth (DE) contains the remains of microscopic organisms called diatoms, whose shells are composed primarily of silicon. The sharp edges of the diatoms' shells destroy the worms in the chickens' digestive systems through desiccation, which dries out the worm. To use DE to control or prevent parasitic worms, chickens need to ingest food-grade DE along with their feed. Check with your veterinarian to determine exact dosages.
Garlic
Garlic powder can be sprinkled on feed or dissolved in water. Fresh garlic can also be chopped and mixed into feed. Excessive use of garlic might temporarily flavor eggs. Using garlic in conjunction with other remedies could yield better results. The University of Kentucky Extension Service recommends using both garlic and mint plants together for maximum results.
Cayenne Pepper
Similar to garlic, cayenne pepper can be used to help protect your flock against parasitic worms. The exact mechanism for why this works is not known, although a star ingredient in cayenne pepper is capsaicin, which is well known for its ability to improve body functions. Cayenne pepper is not as palatable to chickens as garlic, so you may have to adjust the mixture of cayenne pepper and feed until your chickens are comfortable. As with garlic, chicken eggs might have a slightly different flavor after the introduction of cayenne pepper into the chickens' feed.
Read more: Natural Wormers for Chickens | eHow.com
http://www.ehow.com/list_6122748_natural-wormers-chickens.html#ixzz1BnvuznHz
INTERNAL PARASITE CONTROL: Food grade diatomaceous earth makes a very effective natural insecticide. The insecticidal quality of diatomaceous earth is due to the razor sharp edges of the diatom remains. When diatomaceous earth comes in contact with the insects, the sharp edges lacerate the bugs waxy exoskeleton and then the powdery diatomaceous earth absorbs the body fluids causing death from dehydration.
Food grade diatomaceous earth has been used for at least two decades as a natural wormer for livestock. Some believe diatomaceous earth scratches and dehydrates parasites. Some scientists believe that diatomaceous earth is a de-ionizer or de-energizer of worms or parasites. Regardless, people report definite control. To be most effective, food grade diatomaceous earth must be fed long enough to catch all newly hatching eggs or cycling of the worms through the lungs and back to the stomach. A minimum of 60 days is suggested by many, 90 days is advised for lungworms.
Food grade diatomaceous earth works in a purely physical/mechanical manner, not "chemical" and thus has no chemical toxicity. Best yet, parasites dont build up a tolerance/immunity to its chemical reaction, so rotation of wormers is unnecessary.
People often ask why our DE is rated Food Chemical Codex Grade. If it was only labeled as "food" grade, people would think it is only useful as a food supplement and since DE "acts" like a chemical by dehydrating insects, it was labeled "Chemical" grade since it acts like a chemical, but it is NOT a true chemical like a pesticide or insecticide. It is perfectly safe for oral consumption.
5% in feed
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I hope this helps