At a time when awareness of respiratory disease is high, John Ellis, a professor of veterinary microbiology at the University of Saskatchewan, told those attending the Dairy Calf and Heifer Association (DCHA) virtual conference recently to follow the lead of Mother Nature when immunizing calves against respiratory viruses.
He advised against choosing convenience over efficacy in vaccine timing.
“Convenience kills,” Ellis said.
Ellis told dairy farmers to get away from the standard practice of vaccinating for bovine respiratory disease for the first time when the calf is two months old.
Passive immunity from mothers is why people don’t all die at as infants, he said. Without passive immunity, people and calves wouldn’t survive and there would be no need for vaccines. A calf would die of E.coli diarrhea without colostrum, he said.
Ellis advocates “building on Mother Nature’s plan” to induce adaptive immunity through vaccinations against bovine respiratory disease.
In nature, to assure “herd” survival, there is early exposure to endemic pathogens, which he calls priming, and repeated exposure to endemic pathogens, which he calls boosting. These principles can be applied to vaccination programs.
COVID-19 is causing such havoc now because it is a “virgin soil epidemic” — people haven’t been exposed to this novel coronavirus, he said. At other times in history, including when European colonists brought new diseases in the Americas, disease outbreaks followed. Many North American natives, without prime or boosted immunity, got sick and died from smallpox, measles and other diseases for which newcomers had herd immunity.
Bovine medicine has led the way for treatment of respiratory diseases, Ellis said.
“We have very good vaccines if used properly,” he said.
He has three main prongs in his approach to effective protection against respiratory disease in dairy animals.
Initially, ensure there is clean, high-quality colostrum for passive immunization.
Then “manage Mother Nature” by using early mucosal vaccination to prime the immune response.
Finally, he recommends using a booster, likely at two months, to create a long-lived immune response.
This basic plan covers the window of susceptibility very well, he said.
“It’s not all or nothing, it’s a graduated response,” he said. It’s a bell curve.
The DCHA two-day virtual conference April 8-9 replaced the group’s planned annual meeting in Madison, Wisconsin. It focused on raising dairy calves and replacement heifers, with speakers highlighting management practices with question and answer sessions for attendees, including dairy and beef farmers, veterinarians, researchers, industry representatives and students.
Although the focus was on best management practices, it was clear that the impact of COVID-19 — which has led to dairy farmers dumping milk — was on the minds of about 200 registrants, representing 28 U.S. states, four Canadian provinces and 11 other countries.