Part 5 of a six part series on worm control in goats
Alternative dewormers: do they work?
by Steve Hart
Extension Goat Specialist
There has been a great increase in interest in alternative dewormers ie. substances used to control worms which are not commercially available drugs or pharmaceuticals. This has been especially true with the continued development of dewormer resistance by worms. Sometimes these are called non-chemical dewormers, but also would include organic dewormers, herbal dewormers, and natural dewormers. Specific substances to be discussed include tannins (including sericea lespedeza), copper oxide wire particles, diatomaceous earth and herbal preparations.
There is some significant scientific data on the several alternative dewormers, but data on herbal dewormers is scarce. The SCSRPC has coordinated research on sericea lespedeza and copper oxide wire particles and accumulated data from several trials. One characteristic of many alternative dewormers is not only the lack of data, but also the lack of consistent data when data is available. For example, in the study of copper oxide wire particles in sheep, the copper oxide wire particles were fairly effective in sheep in all locations, but data in goats were not as consistent, in fact, in three trials at one location, they had little effect, but were effective in a number of studies conducted in three other locations.
Alternative dewormers need to be studied at several locations, with sheep and goats and with different classes of animals ie. kids vs. yearlings vs. mature does. There is not much money available to fund this kind of research which is why we have so little data and understanding of these alternative dewormers. There is a USDA funded study on herbal dewormers for sheep and goats at Lincoln Univesity in Missouri that is progressing. In addition, when one gets into the many different combinations of herbal dewormers that can be used, the research becomes too large to be accomplished. Hearsay data is not very good and in some cases, very few animals were tested. In the next article in this series, we will discuss how to do your own research to see if the dewormer (alternative or conventional) that you use is working in your animals.
Condensed tannins have been shown to suppress fecal egg counts and reduce worms in the digestive tract. Tannins are a large group of polyphenolic compounds that differ in many physical characteristics. Some tannins such as in sericea lespedeza and other plants have been shown effective in suppressing worms whereas tannins in oaks and other plants do not appear to possess those characteristics. There is an excellent summary of research on sericea lespedeza for worm control by ATTRA (Tools for Managing Internal Parasites in Small Ruminants: Sericea lespedeza, http://www.attra.org/attra-pub/sericea_lespedeza.html).
Some work has been done overseas with sainfoin, birdsfoot trefoil, dock and chicory (tannin-containing plants that grow in the US) showing that they too effectively suppress worms. There are several studies that have been done overseas with tannin containing plants, most of which do not grow here or have a very limited area of adaptation (Sulla, big trefoil). One study showed that the tannins in some types of browse are effective in suppressing worms.
Even as much research as has been done on sericea lespedeza here in the US, there is so much that we don’t understand other than it works both as fresh forage and as a dried product (hay, meal, pellets). Feeding in the short term reduces fecal egg counts by half, and longer term feeding appears to kill a portion of the worms in the animal. In addition, fecal egg hatch may be reduced and larval development and motility affected. When goats are grazed on a solid stand of lespedeza or a mixed lespedeza stand (goats do have a strong preference for sericea lespedeza in the middle of summer) and under both scenarios, worm control was such that dewormers were not needed, even in kids.
When animals were grazed on alternate weeks on sericea lespedeza, there was a significant reduction in fecal egg counts, but not as much as for animals grazing sericea lespedeza alone. We do not know if a pasture containing 20% sericea lespedeza will help suppress worms. Can we supplement with sericea lespedeza hay to animals for 10 days each month (or some such scenario) and get a useful reduction in fecal egg counts? There appear to be some differences in potency of some improved varieties of sericea lespedeza. To summarize, we know that sericea lespedeza works (we assume it is tannins in the plant), but we need to figure out more ways to apply that knowledge to our goat production systems.
Sericea lespedeza is a legume plant that grows throughout most of the Southeastern and Eastern US. It is adapted to warm climates and is quite drought tolerant, tolerant of low fertility and low soil pH (as low as 4.5). It was formerly planted for erosion control and used for revegetating strip mines. It is spread by wildlife and is a long-lived perennial plant. It is too well adapted in Kansas where it has been declared a noxious weed.
Sericea lespedeza will not become invasive as long as it is grazed by sheep or goats (it does not produce seed when moderately defoliated) . Cattle often only eat the plant when it is young, because as it matures, the stems become coarse and tough, the tannin content increases and cattle avoid it because the tannins are bitter (cattlemen hate the plant because of this). However, goats and to a lesser extent sheep can tolerate the bitterness of the tannins and consume it well. Improved selections of sericea lespedeza such as AU grazer are more palatable to cattle and mitigate the objections of cattlemen.
Get assistance from your County Extension Service or Natural Resource Conservation Service to identify the plant or you can see pictures of the plant on the web at http://plants.usda.gov/java/profile?symbol=LECU. You may be able to locate natural stands in your area and be able to rent them cheaply for grazing. There is information on planting sericea lespedeza at www.acsrpc.org.
Tannin containing plants may work several ways to reduce fecal egg counts. They have a high level of protein and the protein and tannins interact to improve protein nutrition of animals. Protein supplementation has been shown to suppress fecal egg counts in sheep and goats most likely due to stimulation of the immune system and tannin containing plants may work in this way. Also, these plants grow high off the ground and animals grazing these plants should pick up fewer infective larvae which are on the lower two to three inches of the plant.
There is some research that shows that tannins may bind to the cuticle “skin” of worms and cause damage to it. There are many other proposed mechanisms by which tannins may work, but the important thing is that we have identified some tannin-containing plants that do suppress worms and we can develop this knowledge into application. In addition, there is potential that we may identify other tannin containing plants that suppress worms.
There are a number of varieties of annual lespedezas which were formerly thought to not have tannins, but this needs to be reexamined as we now have better tests for tannins. These plants may be helpful for parasite control even if they are proved to not have tannins since they have high levels of protein and tend to grow high off the ground. There are also native lespedezas which grew in the tallgrass prairie and generally rare now on most native range sites. These plants could be useful since some have proven to have tannins.
Copper Oxide Wire Particles
Copper sulfate was found to be effective in controlling the Barberpole worm in the early 1900's and has been used in many deworming solutions since. One drawback was that it typically required 100 cc of solution since copper sulfate is caustic and must be made up in a dilute solution.
Copper oxide wire particles
Copper oxide wire particles (COWP) were developed as a slow release form of copper to treat copper deficiency in Australia and New Zealand. One researcher working with COWP to supply copper observed a reduction in symptoms of worms in the treated animals and in 1990 some New Zealand researchers studied the effect of copper oxide wire capsules on worms. They observed that COWP were effective at removing only the Barberpole worm.
Since our major worm during the summer in the Southeast U.S. is the Barberpole worm, COWP should be effective as a dewormer at this time of year. There have been a number of studies conducted in both sheep and goats in the US in recent years and there is a good summary written by ATTRA (Tools for Managing Internal Parasites in Small Ruminants: Copper Wire Particles).
The work is very clear for sheep; administration of 1-2 grams COWP in a gelatin capsule for ewes or 1.0 g for lambs will reduce fecal egg counts 50-90% and seems to be more effective in growing animals. One must be careful with repeated use of COWP in sheep due to the potential for copper toxicity. However, COWP administration was repeated 4 times during the summer without toxicity. COWP is an effective dewormer for sheep when the Barberpole worm is the predominant species and details on its use in the ATTRA publication listed above.
COWP have been shown to be effective in goats although in three studies at one location it did not appear to be effective because the Barberpole worm was not the primary worm.. However at other locations and multiple studies, COWP was an effective dewormer in goats. Since goats are more tolerant of copper, there is less concern about repeated use of the COWP capsules than for sheep.
Basically, doses of COWP from 0.5 to 2.0 g appeared useful in reducing fecal egg counts from 50-80% in goats and appeared to be more effective in kids than in adults. A recent study on pregnant goats shows promise for the use of COWP incorporated in the feed (fed only once) to reduce fecal egg counts. For details on the use of COWP as a dewormer, refer to the above ATTRA publication.
Trace Mineral Bolus
There have been two experiments at one location using a slow dissolving trace mineral bolus (Small-Trace for sheep, Agrimin Ltd., not available in the U.S.) as a treatment for worms in adult goats. In one experiment, there was a 75% reduction in fecal egg count and in the other study, there was over 50% reduction in fecal egg count. This was thought to be an effect of the copper oxide in the bolus. The bolus seemed to have some beneficial effects in reducing reinfection for 4-6 weeks. Research remains to be done in sheep. The high level of copper may limit the capsule to being used once during the worm season with sheep.
Six part series
Worm control in goats
Part 1: Meet the enemy
Part 2. Managing the barber pole worm
Part 3. Integrated parasite management with FAMACHA©
Part 4. Dewormers and dewormer resistance
Part 5. Alternative dewormers: do they work?
Part 6. Doing your own research and fecal egg counts
This six part series on worm control in goats was originally published in The Goat Rancher magazine in 2008.
Copper sulfate was used for deworming sheep before dewormer drugs were available. Copper sulfate was recommended for control of stomach worms (Barberpole worm) in sheep with 100 cc of a 1 % solution being given to a yearling or adult sheep and half that amount to a 3 month old lamb (USDA Farmers Bulletin 1330, 1925; there are several revisions of this bulletin).
For tapeworms, they recommended 1% copper sulfate with 1% of snuff or powdered tobacco. The tobacco was steeped in water overnight and the copper sulfate added . The dose was 50cc for lambs and twice this amount for a full grown sheep. Other state experiment station bulletins recommended copper sulfate treatment for worms in sheep, often after an overnight fast. Studies at one location showed that 1 1/2% copper sulfate was effective at controlling the Barberpole worm in sheep (AVMA 43:163, 1937).
A more recent study (2008) showed that a copper sulfate drench (following fasting ) caused a 60% fecal egg count reduction in ewes that had just been weaned. However, in another study where copper sulfate was incorporated in the feed for one day, it was not effective as a dewormer. Repeated use of copper sulfate has potential to cause copper toxicity in sheep although some reports indicated its use on a monthly basis for a year.
Higher concentrations of copper sulfate in the drench (than 1.5%) are caustic. One source reported success with feeding a 3.3% mixture of copper sulfate in the salt which appeared promising for several months until sheep died from copper toxicity. When they reduced the concentration in the salt to 2%., it was ineffective at controlling worms. More research is needed on copper sulfate.
Tobacco and Nicotine Sulfate
Tobacco and nicotine sulfate have been recommended in old USDA and State Experiment Station Bulletins for control of parasites. Data and dose are sometimes sketchy in older literature as are quantitative results. It was recommended for control of intestinal worms (bankrupt worm and brown stomach worm).
It must be remembered that nicotine sulfate is a nerve paralyzing toxin with which one hopes to use enough of the drug to paralyze the worm (causing him to turn loose and go out the digestive tract) without using too much, paralyzing (and killing) the animal. The margin of safety between an effective dose and killing the animal is not very wide, so one must be very careful when using this chemical as a dewormer. Most workers used 1-1.5% solution of 40% nicotine sulfate with 100 cc being given to a yearling or adult sheep and half that amount to a 3 month old lamb. It was often used in a mixture with copper sulfate (see above).
It must be emphasized that using these compounds can be toxic to the sheep/goat. If you insist on experimenting with copper sulfate and/or nicotine sulfate, use them with a few cull animals that you won’t mind losing if you do have a problem with toxicity.
Diatomaceous earth is fossilized unicellular marine or fresh water algae called diatoms. It is used as a food ingredient (read the labels on processed foods) and in swimming pool filters. There are cautions about using the swimming pool grade for feeding animals in that it can be contaminated with heavy metals whereas the food grade must be proven to have non toxic levels of heavy metals.
Diatomaceous earth has been used for many years for control of various pests from grain weevils to houseflies.
Goat producers that use it for deworming control often mix it with the mineral supplement or in the feed. Most claims are that it extends the time between dewormings although some claim that it kills worms in goats. There have been 4 or 5 scientific studies and the data consistently show that diatomaceous earth does not kill worms in goats although one study did show that at a very high level (5% of the diet), it had a slight effect.
There is speculation that it may help fecal pellets to dry out faster which could reduce the success of eggs developing into infective L3 larvae. Research conducted on this aspect has not been conclusive. It is very difficult to study the claim that diatomaceous earth increases the time between dewormings.
A problem with herbal dewormers is that active ingredients may vary with the stage of maturity, environment (including soil that it is grown in, fertility, moisture and daylength pattern), processing and/or extraction procedure and variety of plant. If you look at herbal supplements in the pharmacy, the FDA has required manufacturers to standardize the products based on a major active ingredient i.e. Garlic is standardized based on concentration of allicin, a bioactive ingredient in garlic.
When you buy dried cooking garlic for deworming sheep or goats, you have little idea of the concentration of allicin in it. This is the problem for other herbals because the active ingredient may be so low it is nearly zero in one plant material source and another source of plant material may contain higher than average level of active ingredient.
Another problem is that common names do not always refer to the same plant. For example, wormwoods refer to plants of the genus Artimesia which includes several species, some of which have a very high level of artimesinin and some which do not have artimesinin and in one study, the efficacy of artimesia as a dewormer did not relate to its active ingredient artimesinin ie. some other substance must have been active in the plant.
Therefore, when working with herbals, there may be inconsistencies in results for many reasons. The only way to prove a dewormer (alternative substance or pharmaceutical) is working for you is to do a fecal egg count before using the dewormer and 1-2 weeks after deworming on a half dozen or more animals. It may be possible for a consortium of producers to collect data and help identify herbs or herbal combinations which most commonly have an effect and these may be worth more in-depth research.
There has been a good study on herbal dewormers conducted in Pakistan which reviewed 232 studies on bioactivity of plants on helminths (from tapeworms to liver flukes and everything in between). They identified 32 plants for evaluation of their effectiveness as dewormers based on literature and local information from farmers and those providing veterinary services.
They did a tremendous amount of research and identified 6 herbs with significant dewormer activity, most of which do not grow in the US or have a very limited distribution in the US. They also found that alcoholic extracts of the plants tended to be more effective than feeding the plant (or plant part) itself. Similar research needs to be done in the US, but the research required tremendous inputs of time and money.
Various herbs have been used as dewormers, including garlic, ginger, wormwoods, tansy, papaya seeds, pumpkin seeds, extracts of black walnut hulls etc. You can find many recommendations on various goat listservers and web sites, some written articles and word of mouth.
There are even a few commercial herbal preparations available from various goat suppliers or on the internet. Caution, some herbs can be toxic if consumed at high levels! There are a few published scientific studies in recent years on herbal dewormers in goats. In one study, the herbal dewormer, composition not given and different combinations of herbs were used in different years and it appeared to have been fairly effective.
One study showed that a wormwood native to the US (present in all states but Florida and Alabama) reduced fecal egg count by 50% after feeding a pound of air dried material a day for 4 days. There is another published study showed that a commercial herbal preparation failed to control worms in sheep. Another study indicated that herbal dewormers were not very effective (http://nodpa.com/newsletters/NODPANewsFinal_March08_Proof.pdf (Page 16). There are several unpublished studies that failed to see a positive response to garlic.
Many producers swear by garlic and other herbs, but good nutrition and management also have an effect. One producer used a product for 5 years and never lost a goat to worms until they had a dry year and the goats ran out of browse and were forced to graze the grass to the ground resulting in severe goat losses. They had to use conventional dewormers to rescue the remaining animals. Their management was preventing worm problems and not their product.
There is much that we don’t understand about herbal dewormers and therefore, one should not be surprised about different people reporting different results. Remember also that those who have less than positive results are not as vocal as those who have positive results.