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Step up scours prevention efforts

Doug Scholz Published on 27 April 2010
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Scours is not a new problem. But despite all the information available to prevent scours with better management protocols and vaccination, it’s a problem that’s getting worse instead of better. Calf scours, or neonatal diarrhea, continues to be a leading cause of mortality and sickness among dairy calves.

Scours can cause more financial loss to your operation than any other disease-related problem. From antibiotics and electrolyte solutions to veterinarian visits and treatment costs, managing scours on the dairy can cost thousands of dollars in out-of-pocket expenses.

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Worse yet are the upfront costs and future losses associated with each calf that doesn’t survive scours. In fact, a 2007 study by the National Animal Health Monitoring System found that at 56.5 percent, scours was the leading cause of unweaned dairy heifer deaths. Research also shows that calves suffering from scours never catch up. One study documented that heifers treated for scours were nearly three times more likely to calve later than 30 months of age.

Fighting scours does not have to be a losing battle. Both the incidence and impact of scours can be greatly reduced with a relatively simple prevention plan. But before developing a plan with the help of your veterinarian, it’s important to understand what causes scours and how it affects calves.

Scouring calves have diarrhea that ranges from moderate to severe, and results in dehydration, depression and sometimes death. Calves that do survive are often weak and do poorly throughout their lives, which is the reason prevention is so important. Viruses and bacteria destroy the lining of the small intestine, causing large amounts of fluid loss. Some types of scours are more prevalent in very young (0 to 7 days) calves, while others tend to appear later, up to 21 days after birth.

Calves are especially vulnerable to bacterial and viral infections that lead to scours because their immune systems have not yet developed and they are exposed to dozens of disease-causing pathogens in the first few hours of life.

The common culprits
There are several infectious agents that cause calf scours, including viruses and bacteria. The most common pathogens are:

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• Rotavirus
Rotavirus is one of the main viral pathogens involved in calf scours. This virus causes scours in calves during their first day of life. Infected calves are severely depressed with excessive drooling and watery diarrhea; fecal color varies from yellow to green. The death rate may be as high as 50 percent, depending on the secondary bacteria present.

• Coronavirus
Scours from coronavirus happens in calves that are more than 5 days old. These calves are not as depressed as those with rotavirus, and can initially have the same type of fecal material. However, within several hours of scouring, the feces may contain clear mucus. The mortality rate from coronavirus scours ranges from 1 to 25 percent.

• E. coli
Many different strains of this organism have actually been identified and not all of them cause scours. E. coli is always present in the intestinal tract and is usually the agent causing secondary infection. The course varies from two to four days, and severity depends on the age of the calf when scours starts and on the particular type of E. coli. Clinical signs of E. coli scours include diarrhea and progressive dehydration.

• Clostridium perfringens
These organisms can be highly fatal to young calves. There are actually six types of Clostridium perfringens organisms, but Clostridium perfringens Type C poses the biggest threat. This disease has a sudden onset; infected calves become listless, display uneasiness, and strain or kick at their abdomen. Calves may also have bloody diarrhea.

Colostrum is critical
Protecting calves against scours starts before birth by taking steps to improve the quality of colostrum. As you know, colostrum is the lifeblood of a healthy calf. Calves need the right quantity and quality of colostrum at birth to build their immune systems. However, colostrum can vary significantly among cows.

The key is to have a sufficient concentration of immunoglobin (IgG) present in the colostrum so it can provide adequate protection to a newborn calf. Use a colostrometer to test colostrum for its IgG levels, and try to feed at least 250 grams of IgG to calves in the first 12 hours. Another possibility is to feed newborn calves colostrum from older cows rather than first-calf heifers. This ensures a higher level of immunoglobin protection, since older cows have been exposed to many disease-causing organisms.

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Vaccination timing
Vaccination is another important element in scours prevention, as it builds powerful antibodies in the colostrum that foster protection against pathogens that cause scours. A broad-spectrum scours vaccine in particular is like an insurance policy – it gives you peace of mind knowing that your newborn calves will have the protection they need against an otherwise devastating disease.

However, a vaccination program will not replace proper cow nutrition, careful calving management and ongoing sanitation. Once those management practices are in place, attaining high levels of antibody in the colostrum through vaccination has proven effective in protecting newborn calves during the critical first weeks of life.

The ideal time to administer a scours vaccine is eight to 16 weeks before cows are ready to calve. As a general rule, the earlier you vaccinate the cow, the better protection the calf will receive. Talk to your veterinarian about scours vaccination timing. Not all scours vaccines can be given up to 16 weeks prior to calving in Year 1 and you’ll want to make sure the one you’re using does provide that wide window of vaccination timing.

Other important management practices
Preventing calf scours requires careful management of the dam, the environment and the calf. We know that the first step in a scours management program is immunization of the dam, delivering passive immunity via high levels of maternal antibodies passed to the calf through colostrum. But beyond vaccination, following other important management practices will help prevent scours in your herd:

• Provide quality nutrition.
Proper nutrition for the dam is critical to ensure sufficient quantity and quality of colostrum. The precalving ration should include adequate selenium, vitamin E, copper and protein. Also, rotate hay feeding areas for the entire herd to prevent a buildup of disease-causing organisms.

• Make good hygiene a priority.
Calve in a clean, dry environment that’s well-ventilated. Avoid overcrowding and calving in muddy areas. Remove bedding and clean calving areas frequently. Keep calves warm and dry. Make sure hutches/pens are clean and dry, and provide commingled calves with ample space for feeding and rest.

• Vaccinate at the right time.
Cows build antibodies in their blood before passing them down through colostrum, and antibodies move from blood to colostrum four to six weeks before calving. Vaccinate as early as possible to optimize antibodies in the dam’s colostrum.

• Manage colostrum effectively.
As mentioned earlier, calves are born with a naïve immune system, so it’s vital that they receive at least four quarts of clean, quality colostrum within six hours of birth.

Your best resource for scours prevention is your veterinarian; contact him or her to discuss vaccination strategies. Don’t let the deadly trend of scours plague your operation. With proper management practices and an effective vaccination program, you can promote healthy calving and yield healthier profits. PD

References omitted due to space but are available upon request by sending an email to .

Doug Scholz
  • Doug Scholz

  • Director of Veterinary Services
  • Email Doug Scholz

When to vaccinate
Consult your veterinarian first to determine the best scours vaccination program for your operation. It’s important to administer a scours vaccine with broad-spectrum protection from viral and bacterial antigens such as rotavirus, coronavirus and E. coli. Use these timing guidelines to vaccinate cows during the dry period to prevent disruptions in milk production.

First year
• Administer first dose to dry cows and first-calf heifers eight to 16 weeks before calving. Choose a vaccine that provides a wide window for administration timing and allows you to vaccinate up to 16 weeks prior to calving.

•Revaccinate dry cows and first-calf heifers with a dose four weeks before calving.

Second year and beyond
• One dose at eight to 10 weeks before calving, when cows are dry. PD

PHOTO : With proper management practices and an effective vaccination program, you can promote healthy calving and yield healthier profits. Photo by PD staff.

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