Sometimes even the best of intentions can lead to unwanted consequences. Sheila McGuirk, veterinarian and calf research specialist at the University of Wisconsin, found this out while investigating a severe salmonella scours outbreak on a Wisconsin dairy.
They had built a warming area for newborn calves to help get them dried off and comfortable immediately after birth, she recalls. This was a wonderful idea and was done in the best interest of the calves, but it turned out to be a major contributor to the outbreak. The warming station was located right in the middle of the hospital area, which also was where they were treating and housing sick cows. Calves were receiving instant salmonella exposure within hours of birth.
Even in more ideal housing conditions, New York calf management expert Sam Leadley says preventing scours is a numbers game.
"Baby calves' worlds are literally painted with the organisms that can cause scours," Leadley notes. "It becomes a contest between getting and keeping immunity levels higher than the organism levels. We have to constantly fight to prevent the bugs from winning."
But you can win the game. Following is a list of things you can do to help keep immunity levels high and organism pressure low - the two keys to preventing calf scours.
1. Provide sanitary calving facilities.
Fecal-oral contact is one of the primary causes of calf scours. Because newborn calves lie so close to the source, McGuirk says diligent efforts must be made to ensure that every calf is born in a clean, dry, well-bedded area. Individual calving pens also help, as does removing the calf from the dam and calving area within a few hours of birth.
"Maintaining the calving area often falls through the cracks on busy farms," she acknowledges, "but if you want healthy calves, it has to become a top priority. It must be assigned as a regular responsibility."
2. Feed colostrum.
There's no way to duplicate the protective qualities of colostrum, and without it, any other scours-prevention measures could go for naught. (See the related article on colostrum management on page 50.)
3. House calves individually.
University of Missouri veterinarian Jeff Tyler calls group housing for baby calves a disaster waiting to happen. "After calves move into their own housing, their primary source of scours exposure is other calves," he explains. "I recommend one calf per hutch, placed 10 to 12 feet apart."
Place hutches on sandy soil at a slight slope so the area drains well. In addition, you'll want to move the hutches periodically - every three to six months minimum. "Every hutch should be freshly bedded between occupants, and thoroughly power-washed and sanitized when sites are rotated," advises Montezuma, Ga., veterinarian Jim Brett. "A good test of cleanliness is to ask yourself whether you'd be willing to lie down and take a nap in that hutch."
While the experts strongly prefer individual, outdoor hutches, the same rules of isolation, bedding and sanitation apply to individual pens in calf barns, too.
4. Sanitize feeding equipment.
McGuirk has seen contaminated esophageal feeders lead to an outbreak of scours, too. It was a large dairy, and they didn't have enough esophageal feeders or enough time to clean each one properly between feedings. Once more feeders were bought and new cleaning protocols were put in place, the scours outbreak resolved fairly quickly. (See "Rules for cleaning tools" at right.)
5. Don't play "ration roulette."
Once you switch calves from colostrum to milk replacer or whole milk, don't switch back or substitute with one or the other. Some veterinarians and nutritionists recommend a gradual transition from colostrum to whole milk to milk replacer, while others suggest going straight from colostrum to the final form, whether that's milk or milk replacer. "The point is, don't get them started on milk replacer, then switch to whole milk on a day you happen to have surplus waste milk," says Brett. "Work out a plan and stick with it."
6. Be careful with waste milk.
While milk from sick or treated cows may seem like a cheap source of calf feed, its cost can be great if it increases your scours incidence. Although opinions vary about feeding waste milk to calves, the experts do agree that one golden rule does exist: Never feed waste milk from: mastitic cows; or cows known to have mycoplasma, salmonella, or Johne's disease.
When using waste milk for calves, always feed immediately after harvest. Or, to suppress bacterial growth, refrigerate until the next feeding. Pasteurization can dramatically lower the level of scours-causing organisms in milk, but Leadley cautions that it's only temporary.
Pasteurized milk should be cooled to feeding temperature (about 100F) and fed immediately after processing. If it's going into storage, it should be chilled immediately after pasteurizing. "It doesn't take long for hot milk sitting around to grow bacteria back up or over its original levels," says Leadley. Pasteurizing equipment also needs to be cleaned as scrupulously as feeding utensils.
7. Feed a coccidiostat.
All of the experts agree that this is a worthwhile practice to control scours caused by coccidiosis. Studies also have shown that low-grade coccidia infections can hamper immunity and leave the door open for other organisms to invade, making the protection even more important. Most commercial milk replacer suppliers offer a coccidiostat-enhanced product, or supplements can be purchased to mix with whole milk. Feeding a coccidiostat in the calf starter grain also is advised.
8. Control vectors that can spread disease.
Flies can readily spread scours-causing organisms, particularly salmonella, explains Brett. In addition, dogs, cats, birds and rodents also can cause biosecurity breaks.
Be careful not to become a vector yourself. While Brett says it's natural to want to care for your sick calves first, doing so increases the likelihood of spreading the disease to healthy calves. "Feed the healthy animals first, then tend to your sick calves."
Although some of these steps may seem elementary, cows and calves have taught us time and again that following the basics - keeping things simple and consistent - is what allows them to thrive.
Maureen Hanson is a freelance writer from La Porte City, Iowa.
Rules for cleaning tools
New York calf raiser Waneata Mehlenbacher credits attention to equipment sanitation as a major factor in the health turn-around of the calves she manages. She follows the "rinse-wash-rinse-dry" protocol suggested by calf consultant Sam Leadley:
- Rinse bottles, buckets, nipples and esophageal feeders with lukewarm, not hot, water. Milk proteins are susceptible to heat. Hot water denatures the milk and gives it highly adhesive qualities, essentially gluing it onto the surface. This is especially true for plastic utensils.
- Wash utensils using hot water (120ºF or higher), plus sanitizing soap and/or bleach. Make sure the water stays consistently hot from the beginning of the wash cycle to the end; otherwise, the milk solids in suspension will redeposit on the equipment being washed.
- Rinse after washing with warm water and an acid rinse. This can be the same acid product used for the dairy's milking system sanitation. Leave this solution residue on the utensils while they dry. Do not rinse it off before using them again.
- Dry utensils by allowing them to individually drain on a rack or shelf. Avoid stacking pails inside each other, and do not set pails upside down on a concrete floor.
As an alternative to bleach, University of Missouri veterinarian Jeff Tyler prefers orthocresolphosphate (OCP), particularly because it is proven to inactivate salmonella. Georgia veterinarian Jim Brett recommends quaternary ammonia.
If a daily sanitation protocol like this seems too overwhelming, at the very least use individual buckets or pails for each calf, so they are not exchanging pathogens with one another.
Read the four stories covering this topic: Calves vs. scours and pneumonia: The survival challenge, How to prevent calf scours, How to prevent pneumonia, Get the lowdown on scours and Is your colostrum a health serum or bacterial soup?. This article in Spanish