Diatomaceous Earth (DE)
Is it an effective natural anthelmintic for sheep and goats?
A review of the scientific literature
Diatomaceous earth (DE), the skeletal remains of single-cell algae, is often touted as an effective and alternative anthelmintic for sheep, goats, and other livestock. DE is said to kill worms by slashing them with its blade-like surfaces. However, there is a lack of scientific evidence to support its use.
North Carolina (2009)
In 2009, a study was conducted at North Carolina A&T State University to determine the effect of DE on goats naturally-infected with internal parasites (primarily Haemonchus contortus, Eimeria, and Trichostrongylus spp.).
Twenty Spanish and Spanish x Boer does (avg. 88 lb.) were randomly assigned to four treatment groups. For eight days, they were treated with DE at different concentrations: Group 1, 1.77 g DE; Group 2, 3.54 g DE; and Group 3, 5.31 g DE.
The DE was mixed with 150 ml of sterile water and administered as a drench. Goats in Group 4 were drenched with sterile water and served as untreated controls.
The goats were kept outdoors in sheltered pens with concrete floors. They were fed a concentrate diet.
Body weights, fecal egg counts, packed cell volume, and white (WBC) and red blood cell (RBC) counts were measured weekly for six weeks. Over the duration of the study, increases in fecal egg counts were observed, and packed cell volumes decreased in all groups. All groups exhibited increases in WBC and decreases in RBC counts. An anthelmintic effect of DE was not observed, as there were no significant reductions in fecal egg count as a result of DE administration.
United Kingdom (2005)
In 2005, British researchers carried out two experiments to assess the efficacy of DE as an alternative to anthelmintics in grazing ruminants (cattle and sheep). Animals treated with anthelmintics and groups of untreated animals were included for comparison.
In the first study, 18 cattle (yearling Black Welsh heifers) were assigned to three treatment groups: 1) control group - no treatment; 2) treatment with an anthelmintic drench prior to turnout; and 3) a daily supplement of DE (2% of daily DM intake). The DE was mixed in with a ration of rolled barley. Groups 1 and 2 received a similar ration of rolled barley. The duration of the study was 10 weeks.
There were no significant differences between treatment groups for live weight gain. In week 7, cattle in the control (untreated) group had higher fecal egg counts than the drench or DE groups; however, for all other weeks, fecal egg counts did not differ between the three groups.
In the second study, 45 single-bearing pregnant ewes were assigned to three treatment groups (balanced for live weight and fecal egg count): 1) control - no treatment; 2) treatment with an anthelmintic prior to turnout (with lamb); and 3) daily supplement of DE post-lambing.
As with the cattle, the DE was mixed in with a ration of rolled barley that all of the ewes received every morning. Ewes and lambs grazed pastures that had not been grazed for at least three months. The duration of the study was 8 weeks.
There were no significant differences in fecal egg counts between treatment groups prior to or post-lambing. Ewes in the DE group had heavier post-lambing live weights than ewes in the drench group, but not the control group. By 10 weeks of age, lambs from DE ewes were significantly heavier than lambs from ewes in the drench group, but there was no statistical difference between lambs in the DE and control groups.
The Inclusion of Diatomaceous Earth in the Diet of Grazing Ruminants and its Effect on Gastrointestinal Parasite Burdens. International Society of Organic Agricultural Research. 2005 Conference.
Two trials were conducted by Iowa State University in 1994 and 1995 to access the efficacy of DE as a natural anthelmintic. In the first trial, 24 weanling lambs were assigned to four treatment groups: 1) uninfected controls - no treatment; 2) infected controls - no treatment; 3) uninfected treated - DE fed; and 4) infected treated - DE fed.
In the uninfected groups (1, 3), lambs grazed clean paddocks, whereas in the infected groups (2, 4), lambs grazed paddocks that had been grazed in the early spring by infected ewes and their lambs. Lambs in all groups were fed 1.1 lbs. (0.5 kg) of concentrate daily. In the treated groups (3, 4), DE comprised 5 percent of the concentrate ration. Samples and measurements were taken at 3 week intervals. A lamb from each replicate of each treatment was selected for a more detail evaluation of the digestive tract.
DE failed to demonstrate economic value, as no death losses were experienced and weight gains were not statistically significant between the groups. There were no differences in hemoglobin or packed cell volume. While fecal egg counts were numerically different between the controls and DE groups (favoring the DE group), no statistical difference was identified, due to the large variability in each group.
The second trial was expanded to 32 lambs and DE was increased to 10 percent of the concentrate ration. The trial was lengthened from 66 to 117 days. In addition, all lambs were dewormed with ivermectin at the start of the trial. One lamb from each replicate of each treatment was selected for a more detail evaluation of the digestive tract. Between the two trials, twenty lambs were necropsied for GI larvae recovery.
The results of the second trial were similar to the first trial. No statistical differences were detected in weight gain, blood values, fecal egg counts, or GI larval counts. At one point, the DE lambs had lower fecal egg counts, but the differences changed markedly by the end of the trial (in September).
The results of these and similar unpublished studies are consistent: 1) DE does not have an effect on parasites loads as measured by fecal egg counts; and 2) DE does not reduce anemia, as measured by packed cell volume and other blood parameters.
Despite the widespread interest in using diatomaceous earth (DE) as a natural anthelmintic, few studies have actually evaluated its efficacy. Thus, there is a need to do additional studies. The Sustainable Agriculture, Research & Education Program offers farmer-grants that can be used to evaluate alternative dewormers and other sustainable worm control strategies.
In previous studies, DE has been evaluated as a substitute for a chemical dewormer. DE and other natural substances aren't likely to replace chemical dewormers, especiallly as the role of chemical dewormers changes from prophylactic to therapeutic.
On the other hand, there is some speculation that DE may inhibit the development of worm larvae (on pasture). If this is true, DE could help to reduce the level of pasture contamination, which in turn, could reduce the number of animals that require treatment with a chemical dewormer.
When properly used, chemical dewormers are not detrimental to the environment, the animal, or the consumer of the end product. In fact, chemical dewormers tend to be less toxic than the "natural anthelmintics" that were used before the development of modern anthelmintics. However, the goal of all small ruminant producers should be to reduce the number of animals that require treatment with an anthelmintic. Anthelmintics are a valuable, but limited resource that must be managed properly to ensure their long term viability.
For producers who wish to use DE as part of an integrated (or holistic) parasite control program, I would encourage them to regularly monitor their animals for signs of clinical parasitism and the need for deworming. The FAMACHA© system and Five Point Check© can be used to selectively treat small ruminants for internal parasites.
There is no single substance (natural or synthetic) or management practice that will completely control internal parasites in small ruminants. Successful control will require critical thinking and a combination of practices. Furthermore, what appears to work one year may not work the next. Each year and farm is different. Animals also differ significantly in their ability to inhibit parasitic infection and/or tolerate parasite burdens, with there being as much difference within a breed as between breeds.Copyright © 2013
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