PI calves are carrier animals that survive after being infected with BVD virus early in gestation. While uncommon at about 1 percent of the total population, PI calves can appear perfectly healthy and still spread the BVD virus through herds and feedlot pens with great efficiency.
Identification and isolation of PI calves is the cornerstone of BVD-control strategies. Ideally, this occurs at the cow-calf stage, but some stocker and feedlot operations have adopted testing programs to protect animal health in their operations. Based on the potential losses from BVD, producers at any stage probably come out ahead, even if they take a total loss on the occasional PI animal. However, a PI calf that is healthy in other respects represents a significant value, and BVD poses no risk in terms of beef safety. This raises the question of whether producers might have an opportunity to capture some value by feeding PI calves to heavier weights.
Keep them out of the market
There is, as yet, no single answer for the question of what to do with PI calves, says Bill Hessman, a veterinarian with Haskell County Animal Hospital, Sublette, Kan., and operations manager for Central States Testing, a BVD diagnostic service. The best solution varies from one operation to the next, he says, but the most important thing is to keep these animals out of the market.
A few producers, Hessman says, test their cattle and knowingly send PI calves to market without disclosure. In doing so, they risk exposing other cattle through the marketing chain, violate just about anyone�s ethical standards and potentially expose themselves to legal action.