This article written by Dr. Reynold Bergen, BCRC Science Director, originally appeared in the January 2022 issue of Canadian Cattlemen magazine and is reprinted on the BCRC Blog with permission of the publisher.
Producer surveys suggest that 5 to 8% of calves typically die before weaning. High winter feed costs mean you’ve already invested a lot in the 2022 calf crop. That investment is lost when calves die before weaning. Scours and respiratory disease are two leading causes of preventable disease and death in young calves.
Calves rely on antibodies from the cow’s colostrum to fight off common pathogens. If the cow herd is well-vaccinated and well-fed, and if calves consume adequate amounts of high-quality colostrum within the first few hours of life, maternal antibody levels can remain high for several months.
The downside is that maternal antibodies can interfere with injectable vaccines. Vaccines help the immune system practice, like a fire drill. The first attempt may be awkward, slow and uncoordinated, but repeated practice improves performance next time. Similarly, the immune system responds better each time it’s exposed to a pathogen. The second (booster) vaccination produces a stronger and longer-lasting response than the initial (priming) vaccination. If the calf is given a vaccine injection while high levels of maternal antibody are circulating in the calf’s blood, those antibodies will block the vaccine before the calf’s own immune system gets a chance to practice. That defeats the purpose.
“Mucosal” vaccines given in the nose (intranasal) or mouth (oral) avoid this problem. These vaccines work differently than injectable vaccines so maternal antibodies do not interfere with them. Nathan Erickson and colleagues at the Western College of Veterinary Medicine demonstrated this in a recent study funded by your Canadian Beef Cattle Check-off (Evaluation of bovine respiratory syncital virus (BRSV) and bovine herpesvirus (BHV) specific antibody responses between heterologous and homologous prime-boost vaccinated western Canadian beef calves; PMID: 33390597). Continue reading