Editor’s note: The following comments are offered by Jim Reynolds, professor of dairy production medicine at the University of California Davis,Veterinary Medicine Teaching and Research Center.

Biosecurity on the dairy farm

“Calves are usually raised in individual pens or hutches until weaned. This housing has the benefit of keeping calves separated so that pathogens have limited spread between calves. Calf pathogens are mostly spread via oral-fecal or respiratory transmission. The key to controlling oral-fecal transmission is keeping feces from moving between calves. Workers are common fomites that transfer feces and oral secretions. Calf treatment and vaccination protocols must be designed to limited workers entering the actual calf housing. Ideally, treatments and injections are given by workers reaching into the calf hutch without them getting into the hutch.

“Another very important aspect of contagious disease control on calf ranches is to work from youngest to oldest calves. The older calves harbor more pathogens and working backwards from older to younger calves will spread pathogens to the young calves.

“Workers who touch secretions from calves, such as feces or saliva, must disinfect themselves before touching another calf. This includes boots, hands and gloves. Workers should be limited in going into the calf hutch or the house, with the larger plastic and fiberglass houses.

“Bottles and nipples (or buckets) must be sanitized between feedings. Bottles and buckets must be scrubbed with brushes to adequately clean them. The utensils should be rinsed with 100 degree F water, scrubbed with hot, soapy water, and rinsed with clean water. Nipples can be sanitized by rinsing with warm water, soaking in a sanitizer and rinsing.

“Waste milk, or hospital milk, can be an economical source of nutrition for calves but the pathogen load can be very high. Waste milk from dairies often has very high levels of general E. coli and may have Salmonella. It is recommended that mastitic milk not be fed to calves. If hospital milk is used in the program, it must be pasteurized correctly and not re-inoculated or contaminated after pasteurization. High temperature, short time (HTST) pasteurization (165 degrees F for 15 seconds) is preferred over low temperature, long time (LTLT) when large volumes are being pasteurized (over 30 gallons) because of the ramp-up time to the target temperature and the risk of re-inoculating the milk with LTST pasteurization.

“Flies and vermin (rats and other rodents) are real transmitters of pathogens around a calf facility and must be controlled.

“Dead calf removal can be a cause of transfer of pathogens throughout the facility. Calves that are moribund and expected to die must be humanely euthanized quickly for the calf's welfare and to limit the continuing emission of pathogens. The dead calves must be handled by a separate crew from the treatment and feeding crew (at least done as a final task in the morning) and the trailer cannot be used for any other purpose.

Biosecurity leaving the farm
“Calves should be loaded onto trucks and trailers away from the areas that new calves arrive and are off-loaded. The trailers and trucks must be clean before they can be allowed onto the farm.
Accurate logs of all calves entering and leaving the calf facility must be kept. Logs of visitors should also be kept. These records are essential if a disease investigation is required and trace-ins and trace-outs have to be determined.

Summary

  • Biosecurity involves keeping pathogens away from the calves.
  • Everything a calf touches must be as clean as possible from birth, through transport to the calf facility, housing, feeding and treating.
  • Keep calves in positive growth so they can respond to infections with competent immune systems. This will increase the amount of pathogen needed to make them clinically ill, improve response to treatment and decrease pathogen shedding.
  • Pasteurize waste milk correctly.
  • Use contagious disease protocols to minimize spread of pathogens between calves.
  • Control access to the farm and keep records of people entering the farm. Record where calves came from and where they went to.
  • Source calves from good dairies and review health and mortality records by farm.

“Have a veterinarian necropsy calves to determine diagnosis. Analyze health and mortality records by age and disease to determine probable risks.”

Source: Dairy Calf and Heifer Association