This article written by Dr. Reynold Bergen, BCRC Science Director, originally appeared in the March 2025 issue of Canadian Cattlemen magazine and is reprinted on BeefResearch.ca with permission of the publisher.
Calves are born with a completely naïve immune system. Unlike other species, cows don’t pass on any immune protection to their offspring during pregnancy. That’s why it’s so critical for calves to consume at least two liters of high-quality colostrum soon after birth, to give them some protection while their own immune system develops.
The calf’s developing immune system can learn to recognize and respond to disease-causing pathogens in two ways. It can learn the hard way – by being exposed to an infectious disease, surviving and responding more strongly the next time. But it’s better to learn in a safe environment. That’s what vaccines do.
Vaccines teach the immune system to recognize what particular pathogens look like so that it can respond more quickly and effectively if those pathogens are ever encountered in real life. Like any other teaching exercise, repeating the lesson helps it to sink in and establish a stronger memory. Vaccines are the same, so revaccinating or boosting strengthens the immune memory.
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