This short article is intended for those who may not have a working relationship with cocci or the control methods available today. It was written in 2009 and hopefully will be of value to those who may have never been responsible for designing anti-coccidial programs or being responsible for making recommendations for an anti-coccidial program. At this time, anti-coccidial programs are all too frequently based on price of the medication rather than on the properties and actions of those medications. Anti-coccidial programs have, for all intents and purposes, become commodity-based decisions. A more consistent level of cocci control would be achieved by considering the disease itself, the medications available, and the mode of action of those medications.
What exactly is Coccidiosis (Cocci)?
Coccidiosis is a disease of turkeys (and other animal species) that has been around forever. Its control is one of the factors that made our current broiler industry what it has become today. The first really effective anticoccidal medications were introduced in the 1950’s and have grown since then.
Coccidiosis, also called Eimeria, is a single celled intra-cellular parasite. Exactly what does that mean? Well, it means that this is an organism that has no useful purpose in life except to invade living cells and kill them. These single celled organisms live in the gut of the turkey.
They invade the turkeys’ cells that line the intestinal tract. While in the cell, the cocci reproduces (by the thousands and millions) and in the process kills the cell it is living in. This process continues through a number of cycles until it is eventually excreted in the feces in a form that is resistant to the environment (called oocyst). Outside the body of the turkey, cocci matures to a form that can infect yet other birds in the flock—and the cycle repeats itself. Therefore, we need to control cocci for the turkeys’ health. If cocci is left unchecked, it will affect weight gain, feed conversion, and possibly even mortality.
There are seven different species of coccidia that infect turkeys. Of those, the three most important (and the ones you will see in the field) are Eimeria meleagrimitis (E. meleagrimitis), E. adenoeides, and E. gallopavonis.
E. meleagrimitis affects the upper half of the small intestine and causes the intestinal wall to thicken. Death can occur 5-7 days after infection.
E. adenoeides affects poults 2-4 weeks old and causes severe enteritis of the small intestine, ceca, and rectum. Infection can result in severe mortality (up to 100%) after 5 days.
E. gallopavonis affects the ileum, rectum, and half of the ceca. Lesions are similar to E. meleagrimitis with a thickened intestinal wall and empty digestive tract.
These are the three species we try to control to maximize weight gain, feed efficiency, and minimize mortality due to cocci. This brings us to control of coccidiosis.
Cocci Control
In order to control coccidosis, a number of medications have been approved worldwide. Not all of these medications are approved for use in the U.S. and some that are approved are not available for one reason or another. In addition, resistance or reduced sensitivity to some medications is increasing and no new anticoccidial compounds are known to be under development. Again, this is most likely due to economic return on these types of investments. For simplicities sake, cocci control may be accomplished through the use of these control measures: 1. Ionophores; 2. Non-ionophores (chemicals); or 3. Immunity.
Ionophores
Included here are Coban (monensin) and Avatec (lasalocid).
Chemicals
Included here are Clinacox (diclazuril), Amprol (amprolium), Coyden (clopidol), Zoamix (zoalene) and Rofenaid (sulfadimethoxine and ormetoprin).
Immunity
Included here are the cocci vaccines that are commercially available. The birds’ own ‘natural’ immunity should also be considered, although it is limited. Ionophores are considered to be the ‘backbone’ of today’s anticoccidial programs. The cost of these drugs is variable, but generally chemicals are more expensive than ionophores. So, let’s say a few words about each of these control measures.
Coban (Monensin) is the oldest of the ionophores and was actually the first ionophore to be introduced. Coban is beginning to experience some reduced sensitivity. There is a fair amount of ‘leakage’ with this compound meaning cocci may be seen in the turkey gut.
Amprol (Amprolium) has typically been used as a treatment anticoccidial in the water when cocci is seen in a given flock. It is a very effective drug to some extent to bring the cost of the medication in line with ionophores.
Coyden (Clopidol) is a coccidiostatic chemical introduced in the 1960’s. It is a very effective broiler anticoccidial when used properly (like all chemicals). Coyden can be used in meat type turkeys for control of leucocytozoonosis, a parasitic disease caused by the protozoan leucocytozoon smithi. Coyden may be used for a single cycle in any one year. No resistance issues have been seen, but judicious use is appropriate.
Clinacox (Diclazuril) is considered a potent chemical. It was introduced in 2000 with widespread use. Resistance developed rapidly as the product was not used judiciously. It is still effective when used properly and “rested” between rotations.
Cocci vaccines (Cocci Vac-T) are either live attenuated or non-attenuated vaccines that also live and replicate in the hosts’ intestinal cells thus stimulating active immunity. By doing so, a condition of sub-clinical coccidiosis (coccidiasis) is created. The coccidiosis does result in decreased performance of the birds to some extent. When used, cocci vaccines are most commonly placed in summer cycles, where cocci challenge is typically lower.
Cocci Control Programs
The terms “shuttle” and “rotation” are used to describe cocci control programs. A “shuttle” describes the use of different anticoccidial medications in the different feeds (starter, grower, finisher, etc.) during one grow-out cycle.
A “rotation” describes the use of different anticoccidial medications for a given period of time—for example 3 or 6 months. A “rotation” may also be designed around the seasons of the year.
Finally, no matter what anticoccidial medications, shuttle, or rotation that may be used, a good solid poultry house management regimen is a very important part of the overall coccidia control plan.
Reprinted with permission from Best Veterinary Solutions, Inc. Written by Huvepharma Tech Service Group.
