October 2017
Farm & Field

Controlling Coccidiosis in Cattle

An explosion in cases of parasite infection means awareness is key to protecting your herd.


Life cycle of coccidian in cattle

The drought last fall and winter combined with a hot, wet summer has recently resulted in an explosion of coccidiosis cases for cattlemen. To properly protect your investment against coccidiosis, it is necessary to understand what coccidia are and how to control them.

Coccidia are single-celled parasites that live in the intestines. All adult cattle harbor coccidia in their gut, even healthy ones. Coccidiosis is the disease resulting from uncontrolled, rapid multiplication of coccidia. Coccidiosis symptoms can be either subclinical or clinical. Subclinical cases result in decreased feed intake and reduced weight gain, and are difficult to detect due to an absence of diarrhea. Undiagnosed-subclinical cases of coccidiosis are quite common. Many subclinical cases self-limit, but under the right circumstances subclinical cases can develop into clinical disease. Clinical coccidiosis can vary in severity. The most common symptom is watery diarrhea with little or no blood. More severely affected calves may develop a fever, become dehydrated and lose weight. These calves are highly susceptible to secondary infections; that may be what kills them rather than the coccidiosis.

Coccidiosis is most common in young cattle 1-2 months and up to 1 year old. Coccidiosis typically doesn’t occur in the first three weeks of life so isn’t considered part of the neonatal diarrhea complex in calves. Disease usually occurs during wet seasons and is especially prevalent when cattle are in heavy stocking densities and on over-grazed pastures. Cattle in feedlots are susceptible to coccidiosis year-round.

There are 12 species of coccidia found in cattle, but only three species cause disease. Continuous exposure to a particular species of coccidia stimulates an immune response resulting in limited protection against that particular species of coccidia. Therefore, adults tend to be resistant to the development of coccidiosis. Also, calves raised in open pasture conditions will often develop immunity on their own. But calves taken from one environment to another (stocker calves, for instance), can develop outbreaks due to being exposed to a different species of cocci and/or high numbers of oocytes combined with the stress of moving. Cattle that survive are typically immune, but they are often permanently unthrifty due to extensive damage to their intestines.

To manage coccidia, it is necessary to understand their life cycle. The coccidian lifecycle begins when cattle consume infective oocysts (coccidia eggs). Once inside the cow, coccidia are released from the oocyst and invade intestinal cells. Rapid multiplication occurs resulting in the destruction of intestinal cells. In roughly a month, oocysts are formed and passed in the feces. Oocysts are not immediately infective once they are shed into the environment. Proper moisture, temperature and oxygen levels are required for oocysts to become infective. In general, the warmer the weather the faster the development into infective oocysts. When conditions are right, this process can occur in as little as 24-48 hours. Once oocysts become infective, they are very hardy and can remain viable in the environment for up to a year; however, two to three months is the norm. Infective oocysts survive best in moist, shaded areas and can even survive freezing temperatures. When a calf consumes an infective oocyst, the process starts again.

Coccidiostats are drugs that inhibit the development of coccidia. Remember, these drugs do not kill coccidia. Normally, use of coccidiostats before anticipated susceptible periods is an effective management tool in preventing and controlling coccidiosis. Some coccidiostats currently available for use in cattle include monensin (Rumensin) and lasalocid (Bovatec). Use of monensin or lasalocid for coccidiosis control also includes the added benefit of growth promotion in calves. However, remember that use of coccidiostats alone may not provide adequate control under some conditions. Management changes are often necessary as well. Contact your veterinarian for recommendations for strategic use of these and other drugs in the control of coccidiosis.

Also, remember that coccidiosis is not the only cause of diarrhea in calves. Other possibilities include other parasites and bacterial or viral infections. The only way to positively confirm coccidiosis is through a fecal exam. Contact your herd veterinarian for more information.

Calves fed a properly balanced diet are better able to mount an immune response and recover from parasitic challenge than animals deficient in one or more nutrients. Proper nutrition involves providing adequate amounts of protein, energy, water, minerals and vitamins. Antibodies that fight parasitic invaders are composed of protein. Energy is needed to drive the metabolic functions involved in mounting an immune response. Several minerals and vitamins are also directly involved in the immune response.

 In summary, wet conditions are ideal for the development of coccidiosis. Coccidiosis is an economically significant disease caused by an intestinal protozoan. Calves from a month old to 1 year are most susceptible to coccidiosis. Control of coccidiosis involves a combination of drugs and management practices limiting exposure of calves to infective oocytes and minimizing stress. Consult your veterinarian for recommendations for strategic use of drugs in response to coccidiosis outbreaks and to help prevent future outbreaks.

Times of high parasitic challenge can increase calves’ nutritional requirements. SWEETLIX offers a wide variety of mineral supplements, including those medicated with Rumensin or Bovatec. All SWEETLIX minerals now contain Sel-Plex as the sole source of selenium. Sel-Plex presents selenium in the same natural form found in plants and is more digestible than inorganic forms of selenium. These organic minerals are easily absorbed and readily metabolized, thereby optimizing animal performance. Selenium plays an essential role in metabolism, neutralizing free radicals and supporting the body’s normal defense mechanism against infection. Visit your local Quality Co-op, go online at www.sweetlix.com or call 1-87SWEETLIX for more information.


Rumensin is a registered trade mark of Elanco Animal Health.

Bovatec is a registered trademark of Zoetis.

Sel-Plex is a registered trademark of Alltech.

SWEETLIX is a registered trade mark of Ridley USA Inc.


Jackie Nix is an animal nutritionist with Ridley Block Operations (www.sweetlix.com). You can contact her at This email address is being protected from spambots. You need JavaScript enabled to view it. or 1-800-325-1486 for questions or to learn more about SWEETLIX mineral and protein supplements for cattle, goats, horses, sheep and wildlife. References available upon request.