by: Heather Smith Thomas

Some diseases affect reproduction, in bulls as well as in cows. It's best to try to prevent these diseases by making sure the cows and bulls have adequate immunity before breeding season.

Dr. Tom Hairgrove (Extension Veterinarian, Animal Science, at Texas A&M) says producers need to sit down with their own practitioner and design a vaccination program that fits their own situation. “You may have different risks, and different expectations than some other ranch. The risks for disease may depend on who your neighbor is. If it's a retired person with a herd of llamas, the risks will be a lot different than if your neighbor is a cattle trader, always bringing new animals into the pastures next to yours.” If there are some unvaccinated animals or cattle with unknown disease history that might get in with your cattle, the risks are higher.

“Perhaps your neighbor has a lot of at-risk cattle, or perhaps you purchase at-risk cattle. Where do you get your replacement heifers? When you purchase replacement females do you know anything about their herd of origin? Where do you get your bulls, and do you know anything about their herd of origin? All of these questions are important when you start to put together a program for vaccination,” he says.

Every vaccination program starts with calves, to build a foundation for later immunity to disease. This is especially important if you keep heifers or bulls for breeding purposes. “All calves should be vaccinated against blackleg (included in the 7 or 8-way clostridial vaccines), and in the Gulf Coast states I always recommend that people use a clostridial combination that includes C. hemolyticum which causes redwater. Not every region has a problem, but liver flukes are often an issue.” The flukes damage the liver and open the way for infection with this clostridial pathogen.

Producers need to assess their risk for liver flukes and use a combination vaccine that covers redwater disease if there is any chance for a problem. All of the clostridial diseases are deadly, and it's not worth taking a chance, because the vaccine is relatively cheap. “The thing ranchers need to be aware of is what's actually in those combination vaccines. We talk about a 7-way and an 8-way, but different products may contain different combinations. To some people, the 8-way vaccine is the one with tetanus in it, whereas an 8-way to someone else might mean the one with hemolyticum (redwater) in it,” he says.

“Select the clostridial vaccine that fits your area. Some places there are risks for tetanus, and that should be included. “World War I was the first time there was very much experience with tetanus in humans. When soldiers were fighting in Belgium—in farming areas where there were a lot of horses and horse manure in the fields for hundreds of years—there was lots of exposure to tetanus because that was the first war where soldiers suffered many wounds from shrapnel. This is when tetanus antitoxin was first employed to protect wounded soldiers, which led to later development of tetanus toxoid vaccine that could be used to prevent the disease.” Humans and horses are very susceptible to tetanus, but cattle can be also, if they are exposed to a high level of infection.

“When I was in practice I worked in a couple of areas that were very risky for tetanus. One rancher lost several calves just doing routine knife castration. Not every ranch will have this risk, but this just illustrates the need for developing a vaccination program that fits your ranch and your risks,” says Hairgrove.

“In Texas I recommend giving the cow herd a Clostridial booster once a year just to provide protection for the calf via colostrum. Sometimes we also have adult animals die of C. chauvoei (blackleg) and it may be atypical and affect the heart muscle rather than the skeletal muscles. The rancher kicks the carcass and doesn't detect the cardboard crinkle that is typical of blackleg in calves, and doesn't realize it was an internal problem. We documented several of these cases in practice, so I think it's wise to vaccinate cattle annually for clostridial diseases,” he says.

The viral diseases are also an issue and he recommends giving IBR-BVD vaccines. It's important to have good immunity in the herd prior to breeding. The big question is when to give these vaccinations.

Vaccine selection is also important. “Some people just go down to the feed store and want a vaccine for everything. This may not be good, however, because you can get into problems if you double up too many gram negative vaccines. Too much is not always better,” explains Hairgrove.

Assess your risk and then choose the appropriate vaccines. “Is BVD a risk? Yes. Then you need to understand a little bit about the disease, because just vaccinating for it—without understanding the importance of management—may not be adequate. If a person is buying new heifers all the time and throwing them in with the herd with no knowledge of their background, this could skew the whole thing. No vaccine is 100 percent protective,” he says.

Biosecurity can make a big difference. Are you raising your own heifers or are you buying them, and if so, where do they come from? “I always talk about this with producers but also recommend that they vaccinate for BVD and IBR. If your replacement heifers come into your breeding program with good immunity, this is the foundation for future immunity. “Boosters are necessary each year, but it's all about getting that initial foundation—just like giving little kids their shots before they go to school,” he says.

He also recommends using vibrio vaccination (campylobacter), especially if you don't have a closed herd or don't know the status of your neighbor's cattle. “The diagnostic tests for vibrio are not very good. Clinically, trich and vibrio look alike. The bull shows no signs and the cow usually doesn't show much (maybe a little discharge if you look closely), but you just discover you have more open cows or late-calving cows for next year,” says Hairgrove.

“When I was in vet school the general wisdom was that we didn't need to vaccinate the bulls—just the cows. “Actually there has been research with the oil-based products to show that you can potentially clear infection in bulls with that, if you up the dose. You could talk to your vet about this, if vibrio might be a risk in your herd,” he says. If trich might be an issue, bulls can be tested for trich ahead of the breeding season, and infected bulls should be culled.

There is also some risk in vaccinating cows and bulls the day you turn the bulls out. It's better to vaccinate at least two or three weeks ahead, in case any of those animals have a reaction (such as a bit of inflammation, fever, etc.) especially if you are using a modified live virus (MLV) vaccine. This could interfere with fertility and conception.

“Other vaccines that are commonly employed include pinkeye. There is nothing wrong with that product, but make sure you really need it, because it's another gram negative. You may not want to give it at the same time as a lot of other gram negative vaccines,” says Hairgrove.

Ranchers should not neglect to vaccinate their bulls. Even though reproductive losses are mainly in females, the bulls need to be on the same vaccination program to make sure they are healthy and won't spread disease to the cows. It is important to start the bull's vaccination program early (just like you would for replacement females) if you are raising bulls. “You need to be careful which vaccines you put into a young bull before he reaches puberty, however. You can use MLV vaccine for IBR/BVD, but do not use a non-cytopathic MLV BVD vaccine in young bulls--because a non-cytopathic BVD vaccine given to bulls before puberty can cause a chronic testicular infection. I stress the fact that only the non-cytopathic BVD MLV vaccine is associated with this problem. There is only one of those products still on the market, but this can cause a problem in pre-pubertal bulls,” he says. When designing a vaccination program for young bulls you need to discuss it with your veterinarian and determine your risks.

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