Voluntary program to evaluate Johne's disease THE TEXAS Voluntary Johne's Disease Herd Status Program for cattle was unveiled recently at the Beef Cattle Short Course at Texas A&M University by Dr. Gary Warner, Texas Veterinary Medical Association representative on the Texas Johne's Working Group.

Cattle infected with Johne's Disease, caused by Mycobacterium paratuberculosis, have diarrhea and chronic weight loss. Infection usually occurs in calves shortly after birth. Calves are infected by ingesting fecal matter, colostrum, or waste milk containing the bacteria.

However, symptoms usually don't occur until the animal is three years old or older. Infected animals may shed the bacteria in their feces, contaminating the soil for many months prior to exhibiting any clinical symptoms.

Economic losses result from decreased milk production in infected cattle, early culling and decreased slaughter prices.

The purpose of the status program, according to Warner, is to:

Provide a system for herd owners to document the status of Johne's Disease in their herds.

Protect herd health and productivity by minimizing the risk of the disease.

Enhance the market value of a herd.

"Biosecurity issues are reduced when buying and selling cattle to improve herds," Warner said. "It is economically safer with a registry of herds known to be free or at low risk of Johne's."

The voluntary status program consists of annual blood and/or fecal testing of some or all cattle in the herd. If the tests are negative for Johne's Disease, the herd may advance through the four status levels in three years. In addition to testing requirements, there are some restrictions on herd additions.

A herd risk evaluation is done prior to completing the herd testing for Level 1. This evaluation informs producers of existing herd risk factors for spreading Johne's Disease. Owners of participating herds are encouraged to implement practices to prevent the introduction and spread of the disease.

The voluntary status program is not intended to certify a herd as being free of Johne's Disease. Instead, the program establishes the likelihood of the disease being present. For example, a dairy herd with Level 4 status is considered 99 percent likely to be free of Johne's disease, while herds at Level 1 have an 85 percent probability of being free of disease.

"To get started in the program, contact your local veterinarian who will take blood or fecal samples and submit them to an accredited laboratory for analysis," Warner said. "If the samples are negative, then submit the results for certification to the state Johne's epidemiologist, Dr. Dan Baca, Texas Animal Health Commission."

Owners who have test-positive animals are not required to notify the Texas Animal Health Commission.

"This is strictly a voluntary program to register test-negative herds,"Warner said.

The status program is modeled after the United States Voluntary Johne's Disease Herd Status Program by the Texas Johne's Working Group. The working group was appointed by Dr. Terry Beals, Texas Animal Health Commission, and is composed of veterinarians, ranchers, dairy producers, livestock marketing associations and other interested persons.

A complete description of the program is available on the Texas Johne's Working Group Web site at: http://www.tahc.state.tx.us/PRODUCTION/johnes.html.