During the recent AABP conference in Milwaukee, Kay Riddell, DVM, MS, from Auburn University, summarized some recent research on BVD surveillance. Herd-level surveillance, she says, can help determine whether persistently infected (PI) animals are present, indicating a need for individual testing.
Noting that polymerase chain reaction (PCR) tests can detect the virus in nasal or oral secretions, Riddell and her team evaluated methods for “consumption surface sampling” for BVD. The experimented with collecting and evaluating samples from feeders, water troughs, water, and mineral blocks, and determined that feed bunks offered the most promise as a sampling location.
The team then conducted a trial in which they co-mingled PI calves in pens with healthy animals and collected samples from feedbunks at various time intervals after the animals came to feed. They also compared different types of pads or swabs for collecting samples and lengths of refrigerated storage of the samples prior to PCR analysis.
They found the test could reliably detect the presence of a PI animal if samples were collected within six hours after feeding and refrigerated for less than 10 hours prior to analysis. Fibrous cloth pads worked best for sample collection from various types of feedbunk surfaces.
The team also used the test in a commercial dairy herd, collecting feedbunk samples from groups of calves, springing heifers and yearling bulls. The testing method found PI animals in several groups, and the results were verified through ear-notch testing.
When herd-level or pen-level surveillance indicates the presence of a PI animal, individual testing becomes necessary to identify and remove the animal. This method of testing appears to offer a relatively simple and inexpensive method for BVD monitoring.