Protect Your Investments
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.
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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).
What They Did:
A group of 75 calves from the University of Saskatchewan’s beef herd were either given an intranasal vaccine against respiratory viruses (BRSV, BHV-1 and PI3) or sterile water (control) within 24 hours of birth. At pasture turnout (48 days of age) and weaning (6 months) all calves were injected with a 5-way vaccine against BRSV, BHV-1, PI3 and BVD Types 1 and 2. Blood samples were collected each time calves were vaccinated, as well as two weeks after pasture turnout and weaning to evaluate antibody levels.
What They Learned:
Although half the calves had received an intranasal vaccine at birth, both groups had similar antibody levels at pasture turnout. There are two reasons for that. One is that all the calves still had a lot of maternal antibodies circulating in the blood. Another is that the intranasal vaccine simply primed the calf’s immune system; this was the first practice fire drill, so the immune system didn’t respond by producing high antibody levels.
But two weeks after the calves were given the injectable vaccine at pasture turnout, the calves that had been intranasally vaccinated at birth had higher antibody levels than calves that were not intranasally vaccinated at birth. The intranasal vaccine given at birth bypassed the maternal antibodies and primed their immune systems, so their immune systems responded strongly to the injected booster vaccine given at pasture turnout. The intranasally vaccinated calves also had higher antibody levels at weaning (when all calves were given the second vaccine injection), and two weeks after weaning.
Calf numbers were too small to detect differences in illness or weaning weight. Differences in antibody response don’t always equate to better performance or health, but they are a good sign that the vaccines were working.
So What Does This Mean… to Me?
Talk to your veterinarian about your calving health plan. Mucosal vaccines are an effective way to strengthen the immune system in newborn calves. The vaccine used here was designed for respiratory viruses, which cause illness in all age classes of cattle. An oral vaccine is also available to protect calves from viral scours which typically occur in the first two to three weeks of life.
Vaccines are an important part of a disease prevention program, but they aren’t a miracle fix. Vaccines can be overwhelmed by disease pressure. Providing adequate bedding and shelter, regularly separating cows into groups of pregnant, newly calved and cows with older calves, and ensuring calving and nursery pens and pastures are large enough to avoid crowding will help reduce pathogen exposure and spread. The Sandhills and Foothills pasture calving systems are based on this principle. Your veterinarian should be able to help you assess your calving facility and pasture options to help identify animal management and movement options to reduce disease transmission.
No vaccine replaces good mothering, good colostrum and good nutrition. Good quality colostrum is still essential to protect the calf until its own immune system is up and running. Colostrum quantity and/or quality might be down this year, particularly if cows are thin or calves are weak and slow to nurse. Energy, vitamins and minerals are essential to support the immune system in both the cow and calf. Drought can affect the levels of these nutrients in the feed. Discuss your feeding program with your vet and nutritionist to identify the most cost-effective ways to supplement what may be lacking.
Vaccinating calves at birth – on top of tagging and banding and pasting – may sound like one more job you don’t have time for. But the time you invest now can certainly pay off at weaning time.
The Beef Cattle Research Council is funded by the Canadian Beef Cattle Check-Off. The BCRC partners with Agriculture and Agri-Food Canada, provincial beef industry groups and governments to advance research and technology transfer supporting the Canadian beef industry’s vision to be recognized as a preferred supplier of healthy, high quality beef, cattle and genetics.
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