Oregano oil for internal parasite control in sheep, goats, and beef cattle

Final Report for ONE08-088

Project Type: Partnership
Funds awarded in 2008: $9,914.00
Projected End Date: 12/31/2009
Region: Northeast
State: Maine
Project Leader:
Diane Schivera
Maine Organic Farmers and Gardeners Association
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Project Information


Regano is an oregano oil-based product that has been tested in Italy on adult meat goats and beef cows as a coccidiostat. It has been found to be effective in these studies. The aromatic oregano oil works by the same mechanism or action as ionophores, like monensin and salinomycin Na, which are widely used as coccidiostats. Regano alters the bacterial cell membrane by changing its permeability to cations, like H+ and K+.
This project replicated the testing for coccidia done on meat goats, and also on cashmere goats and sheep. The fecal tests also monitored levels of Haemonchus Contortus and tapeworms on some farms that exhibited a significant level of infestation.

I worked with 4 small farms: Ells Farm, Perry Ells, raising Fresian crosses for milk and meat, Meadowcroft Farm, Nan Kennedy, raising cross-bred sheep for wool, Sunnyside Farms, Charlie Vincent, raising Boer goat crosses for meat and Black Locust Farm, Yvonne Taylor raising Cashmere goats for fiber and breeding stock. Each farm has a base level of coccidia and Haemonchus Contortus. Ells Farm and Black Locust Farm had visually observable tapeworms.


Coccidia (Eimeria spp) and other internal parasite infestations are a major problem for many livestock farms. Farm income is negatively affected by reducing the growth rates and weight gains for young animals.
Damage is done when a coccidia leaves the host cell. It causes intestinal cell destruction. Oocysts reproduce at amazing rates and one oocyst can destroy millions of intestinal cells. Damaged epithelial lining cells leak blood or plasma into the lumen of the gut, stop absorbing nutrients and are susceptible to bacterial invasion that can be transmitted into the blood stream. The animals become unthrifty. Their feed efficiency and performance are negatively affected throughout life. Smaller breeding or slaughter stock results from the infection.

Coccidia are normally present in most adult livestock. It is rare that their health is negatively affected. More importantly they become a source of infection for the young-stock. The oocysts survive on wet ground. Stress including housing changes, shipping, change in feed, overcrowding, weaning, or environmental stresses like heat, cold, dampness of any sort makes the animals more susceptible to infestation. It is difficult to avoid any stress when rearing animals so it is common to have coccidia or other parasite problems.

As animals mature their immune system develops a natural resistance to the coccidia. In healthy animals with highly functioning immune systems this happens more quickly. Lambs that are exposed to infection early in life as a result of infection from the ewe and a contaminated lambing ground develop a solid immunity if they are not stressed.

Good management including frequent rotation of lamb pastures and not allowing weaned animals to be grazed where adult animals have been for a least a year will help control parasite and coccidia infestation in young stock. But many small livestock producers are not able to practice the most effective management methods because of a limited land base. For farmers with small herds or flocks, sometimes that each animal becomes more precious, often becoming a pet. The occurrence of coccidiosis in these management systems becomes so predictable that coccidiostats are administered prophylactically.

Parasitism is also a major limiting factor for farmers who would like to become certified organic so they can receive additional income from the sale of their livestock. These farmers with small, limiting systems would benefit from a coccidiostat that meets organic standards.

The continued use of parasiticides prophylactically has resulted in resistance of the parasites to many of the drugs commonly used. This study was undertaken to assess one alternative treatment. A major value of this product is that it can be used prophylactically. This makes it practical on small livestock operations with the limitations of acreage and/or the animals of special value.

Project Objectives:

The fecal tests at each farm were done on the young stock since those are the animals most seriously affected. Regano was give to each animal beginning after the first baseline fecal sample was taken.

The Eimeria behaves slightly differently in each livestock species. The project is structured to account for this difference. The goats will be fecal sampled on days 0, 20 and 64, sheep at 0, 25 and 64.

The last fecal at 64 days or 8 weeks will account for a pre-patent period of 3 weeks. This will give an indication of the effectiveness of the Regano on any parasite that may have been ingested on pasture.


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Materials and methods:

The project was managed similarly at all 4 farms. The number of animals involved in the study varied at each farm. The two sheep flocks each had 28 animals in the study. The goatherds had 15 and 11 animals. At approximately four weeks of age, each young animal in the group had an initial fecal sample taken. These were done by digital, rectal collection. The body condition of the animals was observed at each collection and continually during the study by the farmers. Ell’s sheep flock was also weighed periodically during the study because the animals were also involved in another study on feeding of brewery grains. The lambs at the second farm were FAMACHA scored at the last collection. Both goat herders spent significant time with their animals and were constantly aware of their animals’ condition. The monitoring was done to be sure the animals were not losing condition as a result of the treatment method.

The test groups were given the Regano in their normal ration at a rate of 2gm/100lbs daily. The control group was kept on a site that has like conditions to the test group, including the population of oocysts.

I went to each goat and sheep farm to assist with the initial mixing of the treatment ration. I also performed all the fecal collections at each farm.

The fecal samples were analyzed at the Diagnostic Laboratory at University of Maine in Orono. Quantitative and qualitative tests were run.

After all the data was collected, Kathy Murray, Entomologist of the Maine Department of Agriculture, did statistical analysis. Effects of treatment and farm were compared for each animal species.

Research results and discussion:

Doing on-farm research has a certain level of challenges. One of the sheep farms intending to participate ordered feed with coccidiostat included. So they had to be eliminated. Fortunately another farm was recruited. It was difficult to find goat farms locally that had more than 15 animals that could be included in the study. One sheep farm had difficulty getting the treatment started at the appropriate time. Digital collection of fecal samples in small goats and lambs is also very difficult.

But that said, results were achieved. Small sample size and animal variability should be recognized when reading the results.

SYSTAT 7.0 used to analyze the results. It was a straight ANOVA (not a repeated measures ANOVA).

The average reduction in coccidia numbers after treatment was twice as high in treated and untreated sheep and goats. While on average, coccidia were reduced in treated animals by 39% (sheep) and 51% (goat), due to small sample size the reduction was marginally statistically significant (p = 0.07). This is higher that the normally considered 5% level. But since it is fieldwork and not as controllable it is considered significant.

In goats, the average amount Trichostrongyles, Haemonchus Contortus detected was reduced 100% in treated compared with untreated animals, and this was statistically significant (p = 0.029). In sheep, while not statistically significant, the treated animals had 87% higher numbers of Trichostrongyles.

There was no significant difference in numbers of tapeworms between untreated and treated animals of either sheep or goats.

The reliability of fecal samples in regard to oocyst or egg production can be variable. Samples were taken at Ells farm of the same animals, 2 weeks apart, when establishing the baseline. Many in the first set of samples were not large enough for proper quantitative evaluation so we had to do it again. There was a great deal of difference in the levels between the first and second sample with no intervention. The production of eggs by the adult parasite varies over time and affects the reliability of the testing to at least some extent.

Research conclusions:

Perry Ells of Ells Farm was very positive about the results of the study. She measured a good rate of gain on the test animals compared to the control animals. Charles Vincent was also very positive about the Regano. He continued to use the product after the study was over.

The other two farmers Nan Kennedy and Yvonne Taylor did not observe as much success with the test animals. It is possible that specific factors affected the results on these farms.

Taylor’s cashmere kids were reluctant to consume the product. It did not mix well with the grain initially. There was an attempt to moisten the mixture but there was still some refusal. One funny kid in the control group kept trying to jump the gate between the groups. He was wild about the Regano.

Due to scheduling difficulties Kennedy’s lambs did not receive the Regano until almost a month after the baseline fecal testing was done. So the lambs were receiving no protection from parasites at a crucial stage in their life. As a result some lambs were lost.

Participation Summary

Education & Outreach Activities and Participation Summary

Participation Summary:

Education/outreach description:

A workshop was presented at Maine Organic Farmers and Gardeners Association’s Farmer to Farmer Conference in November 2009. About 25 interested farmers and two of the participating farmers attended it. There was a great deal of interest in the product because of the need for alternative parasiticides. Perry Ells presented her positive feelings on the results of the study. My presentation discussed what was done at the other farms.

An article available for publication in newsletters will be mailed to each livestock and farming organization in New England including MOFGA, all the NOFA’s, Maine Sheep Breeders Assoc., other state sheep and goat organizations, and state beef organizations.

Project Outcomes

Project outcomes:

For a 50 lb. animal these are the cost comparisons:
Regano 500 in the 10 lb jug has a retail cost of $131.42/jug plus shipping cost
–2gm/day, $.05, $1.80 for two months
–$1.50/5days of treatment
Ivermectin sheep drench
Using these dosage comparisons, the costs for either method of treatment would be comparable, financially.

Farmer Adoption

After the study was concluded, Ells farm wormed all the animals in the control group to improve their health. The group treated with the Regano did not need to be treated. They were growing very well. Perry also commented that there was a reduction of tapeworm segments observed in the treated animals. Sunnyside Farm, Charles Vincent, also felt his animals gained well and were healthy. They are both planning to use the product next year.

Since the results for coccidia control was positive, and especially for Trichostrongyles in goats, it is likely that it will be used more widely in sheep and goats.

Assessment of Project Approach and Areas of Further Study:

Areas needing additional study

This positive result for control of Haemonchus contortus in goats is the most exciting of the study. It should be followed up with additional experimentation. This parasite is one of the most deadly to all small ruminants. It is a blood-sucker and can quickly cause death from anemia. It would be useful to do an expanded study with adult sheep and goats to observe the results for control of this parasite. It addition it is the parasite showing the most resistance to many types of conventional wormers. If a natural prevention for Haemonchus is found would be very valuable to conventional and organic farmers alike.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.