Under Scrutiny

Do phytotherapy products have anticoccidial activity or adverse effects on coccidiosis vaccination?

Dr. Isabelle Guillot, Schering-Plough Animal Health, Germany
Dr. Yannick Frémont, France

Dr. Isabelle Guillot

In recent years, the animal health industry has witnessed a huge rise in the number of phytotherapy products available. Understandably, there are questions about the efficacy of the products and whether they interfere with coccidiosis vaccination.

Phytotherapy products are mainly marketed as nutritional supplements or appetizers. This has two consequences. First, there are virtually no regulations governing these products; for example, no residue studies are required. Secondly, the makers cannot make medical claims. Nevertheless, product names including "cox" imply anticoccidial activity.

Efficacy trial against coccidia

To learn if phytotherapy products have anticoccidial activity, Schering-Plough Animal Health Corporation initiated testing of three liquid products by INRA Tours, a French independent research center. Except for oregano and chestnut tannin, product components could not be identified. Two of the three products had names that included "cox."

There were four groups of birds in Trial 1 (Table 1). Three groups received a phytotherapy product and one group served as a control. All birds were followed until Day 34 and were evaluated for mortality, lesion score, oocyst excretion and weight gain.
The pertinent results follow:

  • None of the products were effective against coccidia.
  • Some of the products resulted in a performance reduction when compared to untreated controls.
  • Only one of the products provided an improvement in weight gain 10 days after initiating its administration. Since no action on coccidial multiplication was observed, this effect could be explained by nonspecific immune system stimulation.

Phytotherapy and Paracox®-5 vaccination

Table1. Protocol for Trial 1.

Trial 2 was also initiated by Schering- Plough Animal Health and conducted at INRA Tours to see if phytotherapy had any adverse effect on Paracox-5 vaccination (Table 2). On Day 1, phytotherapy products were mixed into the feed, then birds were vaccinated on Day 3.
The results follow:

  • The vaccinal response (oocysts per gram or OPG and lesion score after challenge) were not affected by the phytotherapy products.
  • In Group F, mortality reached 10%, primarily because birds refused feed containing the phytotherapy product the first 10 days of the trial; weight among surviving birds in this group was significantly less than among birds in other groups, showing that the use of some phytotherapy products is not innocuous.

Impact of oregano on vaccination

Table2. Protocol for Trial 2.
Table3. Protocol for Trial 3.

Trial 3 was initiated by Schering-Plough Animal Health and conducted at TGD Bayern, an independent German research and diagnostic laboratory, where the impact of oregano on vaccination was studied (Table 3). Birds were vaccinated by gavage. Oregano was administered in feed according to manufacturer recommendations, and oocyst excretion was recorded daily.

After the end of vaccine excretion on Day 38, birds were each challenged with 10 doses of Paracox-5. This nonvirulent coccidiosis vaccine was used because the trial site was not isolated.
The trials showed that:

Vaccine response was similar in all three vaccinated groups. In other words, oregano did not interfere with coccidiosis vaccination. In fact, the vaccinated group that received oregano in starter feed excreted more oocysts at Day 10 than other groups.

Oocyst excretion after challenge was low in all vaccinated groups due to developed immunity. Coccidial excretion was higher only in the group that received oregano, which shows that oregano has no impact on coccidial multiplication.


Based on the phytotherapy products tested in these trials, it appears that phytotherapy products have no anticoccidial activity nor do they affect vaccination with Paracox-5.

It is possible that some phytotherapy products that were not tested in these trials might have benefits such as natural growth promotion or regulation of gut flora. If this is the case and poultry producers choose to use a phytotherapy product, it appears that they can do so without fear that the product will interfere with coccidiosis vaccination.

1. Detailed results for all trials in this article are on file at Schering-Plough Animal Health Corporation.

Source: CocciForum Issue No.9, Schering-Plough Animal Health.
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