July/August 2021 California Cattleman

Page 52



FIVE STEPS TO PROTECT AGAINST PERSISTENTLY INFECTED CALVES from Boehringer Ingelheim Vetmedica Persistently infected (PI) calves continue to be a substantial threat to all segments of the cattle industry, but many producers don’t even know they are in the herd. “A PI calf is an animal that acquires bovine viral diarrhea virus [BVDV] from its mother in utero,” said John Davidson, DVM, DABVP, senior associate director of beef professional veterinary services, Boehringer Ingelheim. “The calf can often go its whole life without showing visible signs, while still shedding BVDV and exposing the rest of the herd to the virus.” An infected herd will experience unexplained health problems such as calves born with abnormalities, abortions and lowered pregnancy rates. There will also be more bovine respiratory disease cases and substandard weaning weights compared to uninfected herds. The good news is that it’s never been easier to get serious about controlling BVDV PI calves. We know more about the virus, detection and how to prevent the virus than ever before. Following the steps below can help protect your herd. Step 1: Keep detailed herd records. “You can’t manage what you don’t measure,” asserted Davidson. “Records are an important part of any health program, but especially for identifying issues such as PI calves and BVDV problems. They’ll help you spot changes in reproductive performance, productivity and morbidity rates, which can then help you piece together a BVDV diagnosis sooner.”

52 California Cattleman July • August 2021

Step 2: Confirm your records with diagnostics. If you suspect BVDV is impacting your herd’s productivity, the next step is to perform diagnostics. In large operations, veterinarians might initiate surveillance with pooled samples to net down the average cost per head. This will help determine if BVDV is part of the issue. Any pools with positive results are followed up with individual tests to identify PI calves. All bulls, replacement heifers and dams of PI calves should be tested as well, and positives should be culled or isolated from the rest of the herd. Step 3: Ensure heifers are eligible for breeding. Another step that’s often missing from the herd calendar is evaluating heifers’ reproductive status before turnout. “We have done a really good job conducting breeding-soundness exams on our bulls,” said Davidson. “Now we need to implement a similar and equally important evaluation of replacement heifers to ensure they are sexually mature and eligible for breeding.” This pre-breeding herd event is a critical opportunity to begin preventing BVDV PI calves with the inclusion of the right vaccine. Step 4: Protect your herd with biosecurity. For cow-calf producers, it’s important to separate ...CONTINUED ON PAGE 54

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