PI Testing Cattle – What is it?

PI tests prepared for wheat pasture cattle. (Photo courtesy of Dustin Shelton)

By Jessica Crabtree and Dr. Jered Harlan, DVM

What does PI mean in PI testing? –
The term PI stands for Persistently Infected.
Why is it important to test PI cattle?
In a recent article by the Noble Foundation on www.noble.org titled, “Why Test for Cattle Persistently Infected with Bovine Viral Diarrhea Virus,” the article reveals within the U.S., PI positive cattle in a beef herd range four to 10 percent. Cattle PI positive are the primary reservoir for BVDV infection in cattle herds and, therefore, are the major focus of control in cattle programs.
What are PI positive cattle infected with?
PI testing is used to monitor the virus, BVDV — bovine viral diarrhea virus—known for commonly causing respiratory and reproductive issues in the herd, which in turn causes producers major economic loss. Specific problems equal poor reproductive performance ranging from reduced pregnancy rates, increased abortion rates and stillbirth, decreased weight gain, decreased milk and death. Also calf performance deteriorates with increased sickness and death loss. BVDV is known as one of several world-wide pest viruses to infect both domestic and wild ruminants.
How can you PI test your herd?
The Washington Animal Disease Diagnostic Laboratory (WADDL) at Washington State University is implementing a testing program called “BVD-PI Ear Notch Testing Program.” What this program is designed to do is aid the entire herd on identifying and removing BVD-PI animals. Experts shared that each herd should be examined on a case-by-case basis and producers should seek guidance from their vet.
How do you BVD-PI Ear Notch Test an animal?
Each animal within in a herd needs to have a “pig ear notcher” size piece of ear submitted. It is no larger than a dime and is virtually harmless to the bovine. The piece of ear taken with an ear notcher is then placed in a blood serum tube, the red top tube, with one ear notch per tube. After, each individual tube must be labeled with the animal’s individual identification number. Ear notch samples offer producers a great option.

To read more pick up a copy of the January 2017 NTFR issue.