DATELINE : DAIRY
Stealth Bomber

Coccidiosis still slips into dairy herds undetected - and results can be costly

Most dairy producers recognize the clinical signs of acute coccidiosis - bloody diarrhea, long strands of intestinal lining in watery, mucus-filled stools, straining to defecate without stool.
From experience they also know that, if left unchecked, coccidiosis can lead to mortality rates of 2 to 5 percent. Those that do survive become "poor doers" and take significantly longer to mature, breed and reach the milking line.

FAST FACTS

Subclinical coccidiosis can be even more costly than acute infections.
Every oocyst ingested by a calf can return 15 to 28 million to the pasture.
Getting an early start on coccidiosis prevention can decrease morbidity and mortality from respiratory disease.

Fortunately or unfortunately for dairy operations - depending on how one looks at it - acute coccidiosis and its telltale signs appear in only 5 percent of calves. But that doesn’t mean the rest of the herd isn’t infected or losing money.
Subclinical, or chronic, coccidiosis can be even more costly because it usually goes undetected. Infected cattle appear "healthy" as this stealthy intruder quietly slips into cattle and robs producers of gain and performance dollars - without leaving any obvious damage behind.

Know your enemy

To understand how coccidiosis works, one needs to understand what causes the disease and how it manages to evade radar on most dairy operations.
Coccidiosis is caused by highly prolific microscopic protozoa parasites. Two species, Eimeria bovis and Eimeria zuernii, are responsible for the majority of clinical coccidiosis in cattle and are found virtually anywhere dairy herds are present.
The disease is transmitted from one animal to another through an infecting egg, or oocyst, found in feces, soil, pastures and stalls. Because cows are carriers and readily shed the organism, new calves come in contact with oocysts as soon as they hit the ground. And after that, they’re exposed to millions more.
According to published reports, for every one oocyst ingested by a calf, 15 to 28 million - none visible to the naked eye - can be returned to the pasture or stall at the end of the oocyst’s life cycle in 3 to 4 weeks. Ingesting only 50,000 oocysts, or 0.1 percent, of the estimated 50 million a cow passes each summer in her manure can cause severe intestinal disease.

Acute coccidiosis

To avoid bouts with coccidiosis, calves need to consume at least 4 quarts of colostrum within the first 12 hours of life to boost their immune system. A clean, dry environment is crucial as well - a tall order for any livestock operation.
"In the first month of life, calves without adequate colostrum intake are susceptible to death from acute coccidiosis," says Dr. Bert Stromberg, professor of veterinary science at the University of Minnesota College of Veterinary Medicine.

‘By the time we see the clinical signs of acute coccidiosis,
many calves have already experienced extensive intestinal damage’M
Once clinical signs of coccidiosis are present, the disease is more than halfway through its life cycle, making treatment difficult.
"Unfortunately, by the time we see the clinical signs of acute coccidiosis, many calves have already experienced extensive intestinal damage," points out Stromberg. Rather than waiting for coccidiosis to strike, many experts recommend preventive treatments for all animals.

TWO OPTIONS FOR EARLY CONTROL

Calves can become infected with coccidia as soon as they hit the ground. Adding an anticoccidial to the milk replacer can therefore go a long way toward preventing infection and avoiding losses from acute or chronic infections.
There are two options for managing coccidiosis while calves are on milk replacer:

Bovatec® (lasalocid) kills coccidia before they damage the intestines while reducing total oocyst shedding by 97 percent when compared to infected calves. It also helps to optimize weight gain and feed efficiency.
Studies show that Bovatec is highly palatable and can be used with no reduction in feed intake. "Good palatability is important because it means more of the drug is available to fight coccidiosis and reach an optimum control level early in the calf’s life," explains Dr. Lance Fox of Alpharma.
Bovatec has also proved to be a safe ionophore, with a toxicity level half that of Rumensin® (monensin).

Deccox® (decoquinate) is a powerful anticoccidial feed additive that works in the small intestine, where coccidia spend 71 percent of their life cycle. It also keeps coccidia from entering the large intestine, where stress can trigger a clinical outbreak.
Like Bovatec, it can be used at full dose with no impact on intake. It is also approved for use with Aureomycin® (chlortetracycline), which treats bacterial infections caused by Pasteurella multocida.

Both Bovatec and Deccox may be used until the calf is 20 months of age. Producers should contact their feed supplier or Alpharma representative to determine the best anticoccidial program for their operation.

KEY FACTORS IN COCCI CONTROL

Common sense and good animal husbandry practices go a long way toward promoting calf health. The first weeks of a calf's life are critical. With a life cycle of 3 to 4 weeks, coccidia can begin the infective process soon after calving with coccidiosis outbreaks occurring as soon as four weeks after birth.
Because coccidiosis outbreaks in young calves result in mortality rates up to 5 percent or higher, it’s important to handle these calves well from day one, says Dr. Bert Stromberg of the University of Minnesota.

Follow this checklist to ensure optimum health and performance:

Ensure adequate colostrum intake within the first hours of life
Tidy up - keep calf hutches, pens and pastures clean and dry
Isolate sick calves to prevent disease spread
Clean and disinfect boots and wash hands after treating sick calves
Follow strict sanitation practices when moving between cows and calves
Keep feed off the ground to avoid ingestion of coccidia
Use an approved anticoccidial, beginning in the milk replacer
Continue the anticoccidial in the starter and grower feeds to avoid lapses in coverage

"Prevention through the feeding of anticoccidials - beginning with milk replacers and starter feeds - is much more effective than treating coccidiosis outbreaks," explains Stromberg.
Once the calf’s gut lining is damaged by coccidiosis, it has difficulty repairing the tissues to the level of original absorptive action - even after disease symptoms are gone. According to Stromberg, the loss of significant functional gut to coccidiosis makes it hard for the calf to get back on track.

'Calves with subclinical coccidiosis really
don’t give you any specific clues or symptoms'
"A calf that survives an outbreak may never realize its gain and growth potential," he adds.

Subclinical coccidiosis

The elusive subclinical infections of coccidiosis require more vigilance to avoid significant losses. Because this form generally goes undetected, diagnosticians have had difficulty gathering significant data showing its prevalence, even though they know coccidiosis is definitely out there. According to a 1998 report in Dairy Herd Management, the real losses from coccidiosis occur in the 95 to 98 percent of coccidiosis infections that go undetected. "Calves with subclinical coccidiosis really don’t give you any specific clues or symptoms to pick up on," observes Stromberg. "Unless a routine fecal exam turns up thousands of oocysts, no one suspects the presence of coccidiosis." Today, the best-managed dairy herds recognize coccidiosis as a continuous potential threat, says Stromberg. "Progressive dairies are aware of coccidiosis and use approved anticoccidial, starting in the milk replacer, to stay ahead of the game and protect the health and digestive system of the dairy calf," he adds. Dr. Lance Fox, a technical service veterinarian at Alpharma Animal Health who works closely with the disease, also agrees that prevention is the best strategy because it makes cattle less susceptible to respiratory problems.

'Progressive dairies are aware of coccidiosis
anduse approved coccidiosis, starting in the milk replacer...'
"By preventing coccidiosis early in the game, beginning with the milk replacer, you eliminate the suppressive effect that coccidia have on the immune system. That in turn allows the immune system to respond better and effectively to secondary infections and respiratory disease, thereby keeping calves healthier," he says.
Because calves are most susceptible to coccidiosis from birth to 6 months, Fox says it’s critical to start using an anticoccidial in the milk replacer and continue with approved treatments in the starter feed so animals can stay healthy and grow efficiently.

Preventing an outbreak

According to Stromberg, well-managed dairies also rely on sanitation to help keep the oocyst levels down. Clean, dry calf hutches, deep dry bedding, manure removal and employee sanitation all play an important role in reducing oocyst transmission. He cautions, however, that sanitation and preventive measures can be undermined by stress on the calf.
"Animals under stress often reduce their feed consumption, opening the door for infection," he says. "Multiple stressors combined with a large enough dose of coccidia can overwhelm a calf’s immune system, making an infection imminent."
Heat stress, cold stress, change in feed, moving, processing, castration are all stress factors that can weaken a calf's immune system. "Some stressors you have no control over," Fox adds, "so an anticoccidial is needed to prevent outbreaks and to stop losses from hidden infection."

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Bovatec®, Deccox®, and Aureomycin® are registered trademarks of Alpharma, Inc. Rumensin® is a registered trademark of Eli Lilly & Company.

DATELINE : DAIRY Stealth Bomber