Avoiding disease in dairy calves

Raleigh, NC - Calves are the future of a dairy farm, so keeping them healthy is a vital issue.

Research shows disease in calves is controlled mainly by management factors, Dr. Geof Smith, North Carolina State University Professor of ruminant medicine and calf health specialist, said during the DAIReXNET presentation, "Avoiding Disease In Dairy Calve

s".The overall focus should be on management, not products or interventions. "There are certainly specific products out there that may help us avoid diseases in dairy calves, but the vast majority of diseases and calf health problems we deal with stem from improper management and/or poor facilities," Smith said.

There is no magic bullet to overcome a poor colostrum program or bad housing or substandard hygiene, he stressed.

Calf mortality

Studies show nearly 8 percent of U.S. dairy heifers die before weaning, although it should be less than 4 percent, Smith said, and only 40 percent of dairy farms can raise enough heifers to supply their own needs.

The major diseases remain diarrhea at 60 percent, pneumonia at 24 percent and septicemia. "These aren't new major diseases; they've been around for 100 years," he pointed out.

A farm's mortality rate for pre-weaned calves should be less than 4 percent. "If you're over 4 percent, there is definitely room for improvement," he noted. "You should look at your operation, your management your facilities and see where improvements could be made."

A really good dairy will get that number down to 2 percent and even lower.

Treatment rates should be less than 25 percent of calves. "I would say if you're treating more than 20-25 percent of your calves for any one disease, whether that's diarrhea or pneumonia, there's opportunity. Work with your veterinarian to try to improve that," Smith advised.

Disease control

The four key principles of disease control were outlined nearly 50 years ago, Smith noted, and still ring true as the best dairy farmers can do to keep their calves safe.

Remove the source of infection from the calf's environment and keep that environment as clean as possible. Alternatively, remove the calf from a contaminated environment by, for example, moving the calf out of the birthing pen as soon as possible. Increase the immunity of the calf; and reduce stress.

"Really, outside of these four things, there is not much we can do to try to prevent disease in these animals," Smith observed.

Colostrum management

Unfortunately, Smith said, many dairy farms are still doing a poor job of colostrum management. 

He emphasized that a good colostrum management program, meaning one that ensures all calves get an adequate volume of quality colostrum within the first 2 to 4 hours of life, is the single most important aspect of raising calves.

"If you have poor colostrum management, even if everything else is very good, you'll continue to have disease issues," he said.

Dairies with calf health issues should have the farm veterinarian review their colostrum management program and test some calves to see if they have an adequate concentration of antibodies.

There are very clear keys to success. Every calf should receive at least three to four liters of quality colostrum as soon as possible. The sooner the better, Smith said.

Do a good job of harvesting and storage, so colostrum is clean. Bacteria hinders antibody absorption, and contaminated colostrum has been identified as a source of infection.

Do not pool or mix colostrum for multiple cows. "That's a good way to transmit disease and it will, usually, overemphasize poor quality colostrum and lead to more problems with failure of passive transfer," Smith explained.

Make sure the colostrum is harvested in a clean manner from a clean udder and cooled rapidly. Test the calves periodically and have some colostrum in storage, in case it is needed.

"Make this a priority on your farm," Smith urged. An approach he favors is having one person charged with the responsibilities.

Control points

Since calves are frequently exposed to disease from the dam at birth, the maternity area is an important control point. Contamination of the calving area must be minimized by providing good bedding material and removing the calf promptly after birth.

As a rule of thumb, if a calf gets sick within the first week of life, the illness can be traced to the illness to the maternity area. Older than a week, Smith suspects where the calf is housed.

Housing

Calves should be housed in a clean, dry environment with very good drainage. The key is making sure calves are not exposed to manure/runoff from adult cows during their first eight weeks of life. "There's a lot of pathogens in there that don't cause disease for the adult cow, but will cause disease for the calf," he explained.

If using hutches, move them to clean ground between calves. In group housing systems, keep groups small and make sure the calves are of similar ages.

It's also important to minimize temperature stress.

Distancing calves is important. For hutches, the rule is at least a hutch-width of distance between units.

Since calf-to-calf contact increases the risk of pathogen exposure, make sure calves have adequate space, defined as at least four square meters each. If applicable, consider creating barriers to avoid licking, sucking, and manure contact, Smith advised.

Ventilation

In areas where calf barns are popular, pneumonia can become one of the biggest killers of dairy calves. "Studies have linked respiratory disease, or pneumonia, in dairy calves primarily to poorly ventilated housing," Smith said.

It is important to realize that microenvironments exist within calf barns. "That means the air might smell really good when you walk in, but it might be of very poor quality at the level of the calf's nose," Smith pointed out.

The key factors for reducing pneumonia are sufficient straw bedding for the calves to nest, solid panels between the calves in pens with open fronts and backs, and low airborne bacteria counts in the calf pens.

Nutrition

Good nutrition is necessary to maximize host immunity. "Starving calves are more likely to die," Smith said.

Recent research clearly shows that maintaining calves on higher planes of nutrition makes them more resistant to disease. "We're learning more and more on how important nutrition is in keeping these calves healthy," he noted.

In addition, minimize the manure contamination of feed and water and, if feeding whole milk, consider a pasteurizer.

Either limit the use of calf warmers, temporary holding pens, and trailers used for transporting calves, or disinfect them frequently. "These things rarely get cleaned and usually have high pathogen loads," Smith said. "If you have a farm that has salmonella, it tends to be in these things that every calf passes through."

Clean and turn hutches upside down after every use, remove manure frequently from pens and always use clean bedding materials, bottles and buckets.

Avoid stress

Lots of things can stress calves and cause problems. Dietary changes, being moved, overcrowding, weather, weaning and parturition have been shown to increase diarrhea, Smith said, and there is some evidence that bacteria can detect stress in the host and multiply, a feature known as quorom sensing.

Treatment

It's important to learn to identify sick calves early, since most calves will respond well when treatments are started early in the course of the disease. Work with your veterinarian to have treatment protocols in place, Smith advised, and then monitor and record the calves' response to treatment.