Based on the growing knowledge about the economic impact of cattle persistently infected (PI) with bovine viral diarrhea virus (BVDV), stocker producers may find added production and marketing opportunity by getting their arms wrapped around it.

Consider a trial conducted by Bill Hessman, DVM, of Central States Testing and the Haskell County Animal Hospital at Sublette, KS. One of his feedlot clients, Cattle Empire, LLC, began wondering how prevalent the disease and pen-infection rate were in their operation. They wanted to know to what extent PI calves were impacting their bottom line.

According to Hessman, the cost per head exposed to PI in that operation is $67.49/head, resulting in a total average cost per head across the entire population of $41.17/head. That's based on the largest PI trial I've heard of -- 21,743 head across 240 pens.

The trial began in July 2004 at one of the firm's starter yards (10,000-head capacity) where cattle are limit-fed for 60 days and aren't implanted. Every animal was tested. PI animals were removed from some pens and left in others so Hessman and Cattle Empire owners, Paul and Roy Brown, could get a handle on how PI calves influenced pen health if they'd been in a pen then removed, left in a pen, or whether they existed in an adjoining pen to a non-PI set of calves, or ever had.

All said and done, the prevalence rate of 0.4% was just slightly higher than what's usually been seen in smaller trials. But, at least one PI calf was discovered in 71 of the 240 pens for a pen-infection rate of 31%. In other words, about one out of every three pens had been exposed to a PI calf.

Despite longstanding industry conjecture, when Hessman tracked the source of the calves, the infected ones weren't any more likely to come from one particular state than another (10 states were represented). What did increase the likelihood was the order buyer.

Of the 15 buyers who bought 300 or more head represented in the study, the PI-prevalence rate, by buyer, ranged from 0 to 2%. It turned out that buyer behavior contributed to the fact some were more likely to send PI calves. In particular, Hessman said calves bought as singles or doubles through the auction were more likely to be infected.

The resulting pen rate of infection was just as startling. Of the buyers purchasing three or more pens, the rate ranged from 0 to 70%.

These findings mirror those from a smaller trial (2,284 head in 24 pens) in which cattle were tested in Cattle Empire's finish facilities. Using close-out performance to compare between PI pens and non-PI pens, they found a prevalence rate of 0.31% and a pen infection rate of 21%. In sum, the economic damage in that trial was $47.43/head in the pens exposed to PI.

Keep in mind the bulk of the damage came from lost performance in the cattle exposed to PI animals, not to mortality and morbidity among the infected animals. Hessman points out that while many PI calves die early on, some survive all the way to slaughter. Tracking those in Cattle Empire's starter-yard trial, only 25.6% of the calves died during the 60-day starter phase. Of those, 64% of the deaths were due to mucosal disease and 27% were due to respiratory disease. In the smaller trial in the finish yard, 71% of the PI calves survived to slaughter.

Suspicions are that the damage would be at least as significant and probably more so.

Consequently Hessman says cow-calf producers and stocker operators may find added marketability for PI-screened calves. Spun differently, buyers may be willing to pay more for calves that already tested.

Using Cattle Empire's starter-yard trial, Hessman points out the $41.17 cost that PI calves levied on the entire population is equivalent to about $8.23/cwt. on a five-weight calf. That's not what cattle feeders would likely be willing to pay, but at least part of that would provide added negotiation power for produces with screened calves or PI-free herds.

That's in addition to the economic advantages of identifying and removing PI animals from the herd to begin with. For stockers, Hessman emphasizes that by getting rid of PI animals, you'll likely see improved health and performance, along with additional marketing opportunity.

At the very least, it seems this kind of economic impact might make buyers more willing to at least share in the cost of screening calves they're considering for purchase.

It's already apparent that such major feed yards as Cattle Empire are trying to wrap their arms around the problem. Judging by the conversation at the recent Elanco Professional Stocker Operators Symposium, where Hessman presented this information, at least some of this nation's largest and cost-progressive stockers also are in the midst of trying to sort out PI calves as early in production as possible.