Health

HEALTH: BVD

ARTICLE & PHOTOS BY PATINA THOMPSON

BVD is a threat that can be devastating to beef and dairy cattle operations if undetected, and the cow-calf operator is where detection needs to start.

BVD. There, I said it and I’m not talking about underwear, I’m talking about Bovine Viral Diarrhea (BVD) in cattle.

BVD seems to be a topic producers avoid talking about as much as they avoid talking about underwear in public! BVD is a threat that can be devastating to beef and dairy cattle operations if undetected, and the cow-calf operator is where detection needs to start.

Think back through your own experiences over the years, and stories from our ranching grandparents, of those few cows that “didn’t take”, or slipped a calf, a poor doer, or maybe a calf crop that just didn’t quite perform like it did in the past. You might blame the weather (don’t ranchers always blame the weather?), dust off the EPD’s on your bulls, or wonder if you have enough bulls to cover all your cows. Don’t point a finger at those bulls just yet though, these could all be signs of BVD in your herd. But you know what? BVD can be sneaky! You may not notice any signs at all. BVD infected calves/heifers/cows/bulls can gain and perform year after year!

BVD is spread by contact with saliva, feces, nasal secretions, blood, urine, semen, milk, and it can also be contracted by calves while in utero via the placental wall. The time of exposure that is pivotal is the first trimester of pregnancy (months two through four), in which the fetus can contract and carry the virus after birth, IF they survive the pregnancy. Fetal protection is key. A calf born alive with BVD may appear healthy or show immediate signs. Calves may appear weak or be abnormally small, unthrifty, fail to nurse, may have ocular deformities, or a wide stance with swollen joints. The calf may not live past one year of age. Excessive diarrhea is the most common sign in older calves, and a poor growth rate is the most common sign in younger calves. Indicators of BVD in adults may be acute and include fever, depression, loss of appetite, excessive nasal secretions and excessive diarrhea that may last 1-3 days. A BVD positive calf doesn’t mean the mom will be positive either, it just means that the calf came in contact with, and couldn’t defend against the virus at some point. Downright sneaky, isn’t it? So, if properly immunized, healthy looking cattle can still contract BVD even though they may have been exposed to it and fought it off. How is it still in my herd or a threat to my herd? Well, add two more letters to that particular brand of underwear from the 1960’s and you have your culprit. BVD-PI – Persistently Infected. This means that the BVD-PI

individual has the virus, and will continually shed it in the environment for the rest of its life. This is the animal you must find and eliminate from your herd, and I don’t mean taking it to the auction or feedlot and make it someone else’s problem. More often than not, a PI animal is not easily detected visually and must be tested. Testing consists of a small notch from the ear that is sent to a lab for analysis. A PI positive animal should be quarantined from the herd for 30 days, re-tested, and can be safe for slaughter and human consumption if proper withdrawal times have been met. With feeder and stocker operations, this time frame may not be feasible logistically, so separation and a follow-up test after 14-21 days may be sufficient. The good news is that once an animal tests negative for PI, they will always be negative, so you only have to test them once. But remember that a cow that tested negative can still produce a PI positive calf in the future if she is exposed to the virus during that pivotal time during her pregnancy we talked about above. Later term exposure may not produce a PI calf, but it can cause birth defects and other symptoms.

Why don’t all operations test for BVD-PI? Money, time, hassle, you name it. I get that gathering and testing and additional immunizations aren’t how you do it, or how your grandfather did it, or your mother’s cousin that has ranched since the 20’s did it. I get it. But you can add measures to help protect your herd as best you can, and protect the calves you sell from getting it when (not if), they are exposed to it later in life. I also get that you can’t expect a 100% calf crop every year due to weather (there it is again), predators, reproductive age, bulls, etc. However, BVD-PI is one of the myriad of things that factor into your calf crop you CAN control.

A solution is quite simple and three-part, if you put the effort into it. The first step is testing your herd for the presence of BVD-PI. There are a number of labs across the country that charge a nominal fee (from $3.50/head to $5.50/head) for BVD-PI testing. Some of the labs provide all the supplies necessary from start to finish. It’s important to note that not all testing protocols require you test your entire herd, and there are several sampling methods to choose from. Assume a 200 head cow-calf operation tests all of their herd: 200 head of breeding stock, 15 bulls, and 160 calves (80% calf crop). Say, $3.50/head @ 375 head = $1,313.00.

That’s not much in the grand scheme of things, and boils down to the value of two calves in the current market. Is it worth it? I think so! Imagine recouping that income the following year due to an increased calf crop, and continually building up your calf crop percentage one baby step at a time. THAT is where the extra effort and investment pays off. Remember, once a negative PI, always a negative PI, so the initial costs will be the highest. And as an added bonus, that proven, BVD-PI negative tested animal should draw a premium at time of sale.

An immunization schedule that fits your operation is the next step. Vaccines boost individual immunity, and reduce viral shedding. Most veterinarian protocols call for the addition of a modified live virus annually, but be sure to know what stage of pregnancy your cows or heifers are in. Once your breeding stock are tested and on a vaccine regimen, you will only have to test the new calf crop annually to ensure a new infection has not been introduced. Finally, biosecurity is key and the third part of managing the ever present, sneaky BVD. How are you to know if the pairs you picked up just brought it back to the rest of your herd? Or if your neighbor’s cattle aren’t property vaccinated and exchange a nose-nuzzle on your shared fence? What about that slimy manure in your trailer that isn’t washed out when you load the next set in? While some suggestions may be extreme, identifying and eliminating sources of potential contamination and cross-contamination across herds via shared tools, boots and equipment is important to consider. Separation and testing of any new individuals before being added to the herd is also an important measure, and will help in reducing and eliminating the spread of BVD. If you change your mindset to think of testing for BVD-PI as a form of insurance that could increase your calf crop percentage in the future, it’s well worth it. With BVD-PI, prevention is key, detection is critical, and eliminating the source will increase productivity and overall herd health in the long run.

Though the content in this article was approved by a licensed Arizona veterinarian who has been practicing for 4 years, please consult with your veterinarian for consultation on your herd health management plans.

ABOUT THE AUTHOR: Contributor Patina Thompson earned a bachelor’s degree in Wildlife, Watershed and Rangeland Resources from the University of Arizona, Tucson, Ariz. She works in the agriculture insurance field. She is a wife, mother, rancher, hunter, photographer and conservationist in southeastern Arizona.