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Control of coccidiosis in poultry has traditionally relied on the use of anticoccidial drugs. These drugs target specific stages of the development of the parasite with the goal of preventing clinical and subclinical disease from occuring. Anticoccidial drugs can have a coccidiostatic effect (where the development of Eimeria is halted), a coccidiocidal effect (Eimeria is killed in the gut), or both. The use of these medications has been preferred as a preventative measure, as once clinical signs become apparent, it is too late to prevent the consequences of this disease.
There are several types of anticoccidial drugs that are used in the poultry industry including:
- Produced by fermentation and act as both a coccidiostat and coccidiocide
- Examples include: monensin, lasalocid
- Synthetic compounds produced by chemical means
- Examples include: decoquinate, amprolium
Resistance Applies to Anticoccidials Too
Not surprisingly, the continuous use of these drugs has led to the development of resistance in the parasite.
Some of the reasons for resistance include1:
- Inadequate mixing of drugs
- Use of the same anticoccidials for an extended period of time
- Frequency and timing of treatments
Anticoccidial medications are not used to fight bacteria, rather, they are used to fight against Eimeria, a parasitic protozoa. You can read more about Eimeria here.
Anticoccidials are often lumped in as a category with antimicrobial medications. It is important, however, to understand that they can develop resistance to the ‘bug’ they’re intended to fight, much like with our antibiotic medications. This is why we need to be sure we are using these drugs prudently, but we understand the difference. Poultry Health Today has developed a resource to help with differentiation of ionophore medications and antimicrobials, and why the difference is important: The case for ionophores: How they’re different from other antibiotics — and why it matters.
So How Do We Use Coccidiostats Effectively?
To combat resistance, it is suggested to ensure that the correct dose is being given and that the drugs are mixed properly. It’s all about finding the right drug, for the right condition, at the right dosage.
In addition, to further reduce the development of anticoccidial resistance, these medications can be used with excellent effectiveness for treating and preventing coccidiosis in two types of programs2:
Two drugs with different modes of action are used successively in different feeds provided to a single flock. The idea behind a shuttle program includes the use of a coccidia vaccine at the hatchery, followed by the use of an in-feed, non-ionophore anticoccidial medication about 2 weeks later.
Drugs with different modes of action are used in successive flocks to prevent the parasite’s ability to overcome the drug’s mode of action and ability to attach to the cells of the gut.
A rule of thumb is that drugs should be rotated approximately every 4-6 months. For farms that are producing smaller birds, you may be required to rotate more frequently because the number of crops rotating through your barn is increased.
This program can help prevent and prolong the utility of drugs with a strong susceptibility to develop resistance.
What Else is in Your Toolbox?
Although both shuttle and rotation programs have slowed the development of resistance, however, new approaches are needed to control coccidiosis to ensure a sustainable poultry industry.
The number of tools in the toolbox for fighting coccidiosis in the poultry industry are limited. It is of the utmost importance that we are using them appropriately for them to have continued effectiveness. The Poultry Site has developed a video resource outlining the importance of prudent anticoccidial medication rotation as well as management factors that can significantly reduce exposure to birds to prevent disease: Managing anticoccidials: It’s how you use them that’s important. Poultry Health Today has also included an interesting video and article outlining bio-shuttle programs, and the importance of appropriate timing of anticoccidial vaccinations and medications to maximize effectiveness and minimize the chances of resistance development. That resource can be found here: Coccidiosis control: Keys to success with a bioshuttle program.
Work with your veterinarian and service providers to develop a protocol that works for you and your flock!
- Jordan, B., G. Albanese, and L. Tensa. 2020. Coccidiosis in Chickens (Gallus gallus). Taylor & Francis Group, Boca Raton, FL, USA.
- Chapman, H.D. 2018. Applied strategies for the control of coccidiosis in poultry. CAB Reviews. 13.