Diatomaceous Earth

For years we have been reading about diatomaceous earth and its use in controlling parasites in goats. And for years we’ve been reading reports that say diatomaceous earth cannot be proven to have any affect on parasites in goats at all.

Diatomaceous earth is a mineral product composed of finely crushed fossilized shell remains (silica) of unicellular or colonial algae from the class Bacillariaphyccae, better known as diatoms. The microscopically fine, sharp edges desiccate exoskeleton upon contact; and the pests (insects, parasites, larvae) dehydrate and die within hours. The effect is the same as tiny pieces of glass tearing the shells of insects.

There are different grades of diatomaceous earth. The swimming pool grade is chemically treated and often contains crystalline silica which can cause breathing problems. The natural grades are mined, dried, ground, and bagged. They both come from fossil sources.

Many farmers add diatomaceous earth to the rations of their animals, among others, because it contains minerals and is relatively inexpensive. Some claim that diatomaceous earth acts as a dewormer when added on a regular basis in the amount of 2% by weight of the total ration – the USDA approved level.

One manufacturer, HydroMall™ claims, “Both internal and external parasite and insect pest control will result in improvement in health, appearance and behavior, as well as assimilation of feed, which means improved weight gain and lowered feed cost.”

Diatomaceous earth has no effect on lungworm and may actually be a lung irritant. Most manufacturers put a warning on their packaging to avoid inhaling the dust by having adequate ventilation and wearing a respirator or mask when handling this powder. They also advise to avoid contact with eyes and skin since diatomaceous earth can act as a desiccant (drying agent).

We found scientific tests on the subject to be few, and the opinions of farmers who use diatomaceous earth to be contradictory – some swear by it as a wormer while others claim it has no affect at all on parasites. According to Anne Zajac, DVM, PhD, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, Blackburg, VA, “…there have been several studies done by parasitologists in different parts of the country that have found no beneficial effect to feeding it or offering it as mineral.”

Richard Smith, an animal food specialist from Grand Rapids, MI, conducted an experiment by feeding Codex Food-grade diatomaceous earth to zoo animals in Grand Rapids; MI, Chicago, IL; and Buffalo, NY. The zoos in MI and NY reported their black bears on the special feed showed better coats and clearer eyes while the primates at the zoo in IL has improvements in both appearance and behavior. Fecal exams taken prior to using the diatomaceous earth showed parasites present; there was an absence of any internal parasites following the experiment.

In 1999, a 16-week test was conducted at Texas A&M, College Station Texas, to determine the effect of diatomaceous earth in controlling parasites in goats. 79 pregnant or lactating goats of 4 different breeds were used in the test. All goats were wormed using Ivermectin prior to the start of the test; all goats were supplemented with a 12% protein feed during the test. Four groups were randomly chosen. Group 1 (control group) received no treatment. Group 2 was given Ivermectin at weeks 1, 4, and 7. Group 3 was given Ivermectin at week 1 plus Agrisafe Corp’s diatomaceous earth in concentrate. Group 4 was given the diatomaceous earth in concentrate. The findings were that the survival rate was statistically greater for the three groups receiving treatment than for the control group. Another finding was that Ivermectin was only marginally effective in lowering nematode egg counts (Haemonchus was the only genus seen by copro culture). Feeding diatomaceous earth at 2.5% of the concentrate feed ration was the same as a marginally effective anthelmintic in controlling parasites. (The survival rate on the Boer goats was higher than other breeds.) These findings were presented at the American Association of Veterinary Parasitologists 45th Annual Meeting at the Salt Lake City Marriott.

We read that diatomaceous earth can be used as a dust for fleas, lice, and other external pests by rubbing into the coat of animals. We also read repeated testimonials that the use of diatomaceous earth greatly reduced the fly population in barns, so we decided to buy some and give it a try.

After cleaning the barn, we put down a layer of lime. On top of the lime, we liberally spread the diatomaceous earth. While we remain skeptical about using diatomaceous earth as a wormer and have not used it to “top dress” the goats’ feed, we have found it has had a positive outcome at our farm. We found it has a drying effect when put in wet areas. It also seems to absorb some of the urine odor. And while Ken says its all my imagination, we do seem to have less flies.


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Ken and Pat Motes
Clear Creek Farms
33 South Clear Creek Road
Fall River, Tennessee 38468
Phone: (931) 852-2167
Fax: (931) 852-2168


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