Producers who shudder at the cost and effort involved in vaccinating their cattle were recently advised to think about fire insurance.“Most of us are risk averse. We do things to avoid risk,” veterinarian John Campbell from the Western College of Veterinary Medicine told a recent stock handlers conference in Saskatoon.“Fire insurance? It’s a terrible investment. Most of you buy fire insurance all your life, even though you’ll never collect on it. But the reason you buy it is that the bad outcome that can happen is so severe and so terrible that you can’t take the chance that it might happen to you, even though it’s a relatively small probability. Vaccinations are a little bit like that.”Campbell said producers are more likely to forego vaccination programs when beef prices are low because they tend to be viewed as an avoidable cost rather than an insurance policy.The stark reality hits home when infectious disease strikes.Campbell said in one case in northeastern Saskatchewan, the owner of an otherwise well managed herd inexplicably lost 15 calves in four days.Tests showed the calves were infected with bovine viral diarrhea (BVD), which causes fever, nasal discharge, diarrhea and restricted movement in newborn calves.“The cows weren’t vaccinated,” Campbell said. “They had been vaccinated most other years, but they kind of fell behind that year and the cows didn’t get vaccinated. The calves were infected as fetuses in their mothers’ bellies. They got BVD virus and it eventually killed them.”In another case, 30 calves were found dead on a farm in east-central Saskatchewan. Post mortem exams revealed heart lesions caused by blackleg.“The owner didn’t vaccinate,” Campbell said. “It wasn’t worth his time and effort and he lost 30 calves because of it.”Last year, a herd of 450 cows on a farm near North Battleford, Sask., were examined before calving and 140 of them were open. Subsequent blood tests showed high levels of BVD and infectious bovine rhinotracheitis.The acutely infectious disease usually affects the nasal and respiratory passages, but it can also cause reproductive problems and abortion in cows.“The owner stopped vaccinating around 2003 when BSE hit because he thought it was going to cost him too much money.”Campbell said his message is simple: vaccinate or be prepared to face the consequences.Vaccines confer active immunity. Unlike passive immunity, in which antibodies are passed from a source to a recipient, active immunity involves an animal actively producing its own antibodies after being exposed to an antigen.Passive immunity is usually conferred through colostrum, which allows a calf to absorb antibodies through its gut during the first few hours of life.Active immunity is usually the result of exposure to an infection or a vaccine.Diseases that warrant vaccination include BVD, scours, pneumonia, leptospirosis, pinkeye and campylobacter fetus.BVD is a particularly prominent threat in the beef industry. If a pregnant cow is infected with the virus, its fetus also becomes infected.When that occurs, the fetus’s immune system will continue to develop but it will not recognize BVD as a foreign virus.The calf may come to term and be born normally but it will be persistently infected and immunotolerant to BVD.
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