Vaccination programs may look less like a road map and more like a maze to producers.
There are questions on what illnesses they should target. Is a live or killed vaccine best? When should they be given? How long do they last? If it is a killed vaccine, how far apart should the doses be?
The latest educational foray by Manitoba Beef and Forage Initiatives hoped to cut through some of that confusion. Producers took a break from the cold Feb. 20 to take in an afternoon of immunization information at the Brookdale site.
“It’s appropriate to vaccinate your herd for things that could potentially affect them, so we talked about blackleg; we talked about BVD; we talked about IBR,” Minnedosa veterinarian and workshop attendee Dr. Troy Gowan said. “But it’s not only important to vaccinate them; it’s important to vaccinate them at the right time, so if you give them a vaccine at the wrong time, you’re still potentially opening yourself up to still having disease issues.”
For the fetus
Rob Tremblay, representative of Boehringer Ingelheim (Canada) Ltd. and the guest speaker of the day, said vaccination programs will depend on a producer’s goal.
A modified live vaccine will offer more protection for an unborn calf and needs only one dose, unlike a killed vaccine that needs several, but cannot be given to a cow that is already pregnant or to a calf nursing off a pregnant cow, unless the cow has already been vaccinated by that vaccine (or one almost identical) in the past. Tremblay pointed to IBR virus in vaccines meant to protect against BVD. The live virus has been linked to abortions when used to vaccinate pregnant cattle or heifers that have not seen that vaccine before.
Killed vaccines are safe for pregnant animals, regardless of vaccination history, but may not convey the same protection to the fetus, he added.
That balancing act makes timing key if the goal is to protect the unborn calf.
Vaccinating a cow after calving, but before the bull is turned out for the next season, is one of the safest options for a modified live vaccine, the room heard.
“There are some other times that would provide good protection too,” he said. “With some people, if they’re in a situation where it’s safe to vaccinate the pregnant cows, then it could be when they’re giving the scours vaccine, for example.”
Under ideal circumstances, Tremblay would vaccinate cattle 30-45 days before bulls are put out to allow for immunization before conception, but not so long before that immunity might trickle off while it is still needed.
“The reason that I talk about alternative times is that over the last eight or nine years I’ve been asked by ranchers, by farmers, that say, ‘Yeah, well, I know that’s the ideal time, but I can’t necessarily always vaccinate at the ideal time. Are there other times that might not be as good, but I’m still going to get some value from the vaccination program?’” he said.
He suggested producers count backward to find their window to vaccinate. The unborn fetus needs at least 150 days of protection after conception, plus an extra 42 days, or two estrus cycles, between when bulls are turned out and when at least 80 per cent of cows can be safely assumed pregnant.
Farmers can compare that 192 days (rounded up to 200 or down to 190, according to the producer’s comfort), to how long each vaccine’s protection lasts to determine a window to vaccinate.
For a BVD vaccine with effective protection for just over a year, that window should start about six months before bulls are turned out.
“In this case, we’re talking about if you’re going to protect the unborn calf, then you’re going to have to make sure that you’re targeting the timing so that the vaccine that you’re going to use has an opportunity to actually work,” Tremblay said.
The method casts a critical eye on more popular vaccination timings, such as vaccinating during pregnancy checks, something producers may gravitate towards, since they are handling the animals anyway. Unless pregnancy checks fall within six months of bulls being turned out for the next breeding season, however, Tremblay has serious questions about that timing.
“If you start to count backwards from when you actually need the protection, it’s not very many years where preg check time would be the best time to vaccinate, so you’re giving away protection,” he said. “You’re paying for it, but you’re giving away protection because it’s not likely that the cows will be protected enough to get you through the risk period when the unborn calf would be vulnerable.”
Should you vaccinate young calves? And, if so, when?
The question got a sober second look during the workshop.
Tremblay maintains that calves do get protection, pointing to his own company’s research, which has shown an effective vaccination response if vaccinated at seven days old. At the same time, he said, calves cannot be expected to get the same period of protection as they would at six months.
“Part of the information we don’t have is how long that protection actually lasts,” he said. “In fairness, it would be a difficult question to answer anyway because it’s probably influenced by how much colostrum that calf got, how much protection was actually in the colostrum, so it’s going to be a bit of a moving target anyway.”
It’s a question that Gowan has also faced. Many of his clients’ calves are vaccinated young, he said, although with the understanding that they will have to return for a booster. Those calves are usually vaccinated again both before they go out to pasture and when they return in the fall.
“There’s many takes on it,” he said. “Obviously, there’s the concern with maternal interference. We give colostrum. That provides immunity, but does that immunity interfere with the vaccines that we’re giving? I think it’s not black and white. It’s a complex situation.”
Pipestone-area producer Trevor Atchison said most of the information presented Feb. 20 was not new, although he is taking home some reminders on timing.
“It’s always good to review what vaccines you’re using and what they’re supposed to do — the proper timing of when they should be used to get the most benefit out of them for the protection of not only your calf crop after they’re born, but your cow herd leading up to that.”
He is already working on vaccination coverage during pre-breeding for the 800 calves that drop on his farm each spring.
“That was made evident today, that that’s as critical as vaccinating those calves — getting that immunity into that calf for BVD especially,” he said.