An Ounce of Prevention is Worth Pounds of Performance

An Ounce of Prevention is Worth Pounds of Performance
Jan. 27, 2006

Bovine coccidiosis occurs in all breeds of cattle, worldwide and year-round. In the United States, the annual cost of the disease to beef and dairy industries has been estimated at $400 million.

Coccidiosis is an intestinal disease caused by coccidia — a single-celled protozoan parasite. These protozoa have a complex life cycle that lasts 21 days in a host animal and seven days without the host. Reinfection occurs daily, with several life cycle stages occurring simultaneously.

Clinical signs of the deadly disease occur three to eight weeks after infection, when second-generation coccidia sporozoites, called merozoites, penetrate the large intestine. Coccidial infection alters intestinal function, which in turn affects nutrient and water intake from the gut — inviting secondary intestinal infections and toxicity. The onset of coccidiosis induces immunosuppression, allowing secondary infections such as pneumonia to occur.

“Coccidia are opportunistic parasites, existing at subclinical levels until stress factors reduce the resistance of the host animal,” explains Joe Dedrickson, director of Merial Veterinary Professional Services. “Animals with clinical infections may exhibit mild diarrhea, reduced appetite, reduced feed efficiency and a weakened immune system.”

But subclinical animals, which may appear healthy, account for approximately 95% of coccidiosis infections. More importantly, these subclinical animals act as carriers, spreading infection to more susceptible animals through contaminated feed and water. “When clinical signs do appear, much of the damage has already been done,” Dedrickson says.

Research has indicated that cattle may experience reduced feed consumption for up to 13 weeks following clinical infection. Coccidiosis is induced by periods of stress — weaning, processing, shipping, commingling and cold weather. That’s why it most often occurs in cattle 6 to 12 months old, but it also can occur in older cattle, especially in feedlots.

“All cattle in every geography are exposed to coccidial infection during their lifetime, but the extent and severity of the disease, coccidiosis, is dependent upon numerous factors,” Dedrickson says. “In addition to typical stress factors, the role and severity of coccidiosis is dependent on weather, overall herd health, parasite populations and the number of coccidia ingested.”

Cost of therapy to treat an outbreak is considerably more than the cost of early treatment of infections to prevent disease. Products labeled for control limit the severity of clinical signs but do not always prevent a clinical outbreak.

Continuous administration of products for prevention does prevent those clinical breaks; it will not eliminate existing infections, but reduces the impact of subclinical infections. Treatment products administered to animals with clinical signs can optimize performance. “Remember that if there is one clinical case in a group of cattle, it’s likely that the group is harboring coccidia in intermediate stages of development,” Dedrickson says.

— Adapted from original article provided by Merial, from its January 2006 issue of the MERIAL VPS SHARE e-newsletter. The newsletter was developed to address the many educational needs of the beef and dairy cattle industries as part of the overall Merial Veterinary Professional Services (VPS) Strategic Husbandry and Animal Research Education (SHARE) initiative.