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Scours Free

With calving season around the corner, now's the right time to plan for handling one of its most serious problems - calf scours.Last year scours losses skyrocketed in the Northern Plains for two reasons, says veterinarian John Thomson, professor in the Iowa State University (ISU) College of Veterinary Medicine in Veterinary Diagnostic and Production Animal Medicine.* Drenching rains and knee-deep

With calving season around the corner, now's the right time to plan for handling one of its most serious problems - calf scours.

Last year scours losses skyrocketed in the Northern Plains for two reasons, says veterinarian John Thomson, professor in the Iowa State University (ISU) College of Veterinary Medicine in Veterinary Diagnostic and Production Animal Medicine.

* Drenching rains and knee-deep mud hit during the February-March spring calving season.

* Just starting to build back herds after an excruciating liquidation period, there was a higher percentage of first-calf heifers, the class most vulnerable to calf scours, say researchers.

Herds with more than 20% first-calf heifers have a quadruple higher chance of calf scours than those with less than 20%. That's according to a 1994 four-state study of 555 herds totaling 110,000 heifers and cows.

The mean rate of calf scours among these herds was 10.9% and ranged from 0% to 100%. The rate of calf scours was higher among calves of heifers (18.8%) than those from cows (9.5%).

The case fatality rate (percent of clinical cases that died) was about the same in low- and high-mortality herds. "If a calf gets sick, he has the same odds of dying no matter what group he's in," Thomson says. "The goal then should be to prevent scours in the first place."

Other Causes Of Scours Here are other contributing factors Thomson identifies.

1. Over 40% of producers with high-mortality herds added animals to the herds during the stressful calving period. Only 4% added calves in the low-mortality group. Most additions were pregnant heifers, with some cow-calf pairs and foster animals.

"Once you bring in a pathogen your herd hasn't had, or is not immune to, watch out," Thomson warns.

2. About 30% of respondents vaccinated when they detected scours. Early detection and treatment was important, 20% of them noted, while 80% felt environmental management was the biggest key that helped.

There is no common treatment for some of the diseases caused by the parasite Cryptosporidia or rota and coronavirus, Thomson warns. "The biggest benefit of diagnosing this year's crop is to help plan how to avoid the problem next year," he says.

Vaccinations must be given early enough so immunity is built through the mother's colostrum, Thomson says. "We must let body defenses help us fight those infections. Electrolyte therapy can be essential. If we don't have something to kill the organism, we have to provide supportive care to give them time to recover."

3. Herds calving before March 10 in the four Northern Plains states had 1.6 times higher chances of significant scours than those born after that date. Of course, the dates would be different in other sections of the country.

4. Calves fed extra copper (known to strengthen immune systems) had significantly higher calf scours in the study. This contradiction can be explained, however. Thomson says, "Adding copper plus vaccination isn't enough in and of themselves. Managing the environment has to be part of it. Those with high scours problems had management problems in their herds."

5. Calves from cows that lost body condition the last 60-90 days of gestation, thus decreasing a calf's birthweight and vigor, had significantly higher death losses from scours in high-mortality rather than low-mortality herds.

"Anyone living in those areas knows how bad weather sucks the weight off these cows," says Thomson. "You need to take a hard look at nutrition because that weight can come off four times faster than you can put it on."

No Single Solution There's no silver bullet, Thomson says. But he and ISU veterinarian Mel Pence have developed some practical solutions.

The two veterinarians developed a "Calf Flow" pattern (Figure 1) to help control scours through the calving period. The pattern was tested on an operation in central Iowa during calving season in February and March. At the time, mud was nearly a foot deep and conditions were difficult.

The study group included 250 purebred Angus first-calf heifers and 300 cows ready to calve. Thanks to the "Calf Flow" plan, and the dedication of manager Bob Sealock at Rhodes Farm, scours were kept at a minimum.

They followed the flow plan shown in Figure 1. Cows ready to calve go from the precalving to calving area. If not sick, the pair goes to a postcalving area. Those with any signs of sickness go to a sick pen. "It worked. Once they leave the calving area, they never go back," Pence reports.

Thomson's suggestions include:

U Check your vaccination protocol, distribution, entry policy and develop an emergency and bad weather plan.

U Don't bring new animals into the herd at calving time. Identify an isolation area for scouring calves, foster calves and others at high risk.

U Calve heifers separate from cows and keep them separated after they calve. "We have isolation areas for both adult cows and heifers to keep sick animals away from the group," says Thomson. "Don't commingle the groups until the youngest calf is at least three weeks old."

U Beware of public health issues. Remember, many pathogens associated with calf scours, such as Salmonella and Cryptosporidia, can cause clinical disease in humans, Thomson warns. For those working with calving, don't use kitchen areas to mix electrolytes or to get colostrum ready. "You can wipe the counter down, but that doesn't disinfect it," he says.

Every human and animal has an immune system that fights off the "bugs" we're exposed to every day.

In cattle, the immune system is adequate under normal circumstances, says Iowa State University veterinarian Mel Pence. "But when there are too many "bugs" out there, they may overcome that immune system. If you keep that number down, you're still okay. The animal won't get sick. And if it does, it won't be overwhelmed."

A calf's immune system is zero at birth. "The only immunity it gets is from the mother's colostrum," Pence adds. "After a couple of days, the calf can't absorb colostrum anymore. At the same time, the mother's immunity is dropping, so its own has to come up. And if the calf comes from a first-calf heifer, she may not produce a high quality of immunity adequate enough to fight off the bugs."

Pence says there are critical points where a calf is more vulnerable in an environment with lots of bugs - like at calving time when it's muddy. "If the immune system is going down, and we calve in a contaminated environment, we're in trouble," he says.

If the calf gets sick, it sheds viruses and bacteria into the environment. The more the environment becomes contaminated, the greater the calf's vulnerability.

"We need to look at management methods that prevent that buildup of disease-causing organisms and stop the problem before it starts, or at least minimize its effect," Pence says. "We can't pump enough antibiotics, vaccines or nutrients into a calf in a terrible environment and keep it healthy."