The Texas Animal Health Commission (TAHC) has measures in place in an effort to protect Texas’ cattle tuberculosis (TB)-free status, after two more states New Mexico and California lost their TB-free status in September. Minnesota’s cattle TB status was downgraded in April 2008, and in Michigan, only the Upper Peninsula is cattle TB-free. Cattle TB is caused by Mycobacterium bovis (M.bovis), which can be spread when infected cattle cough or snort, and nearby cattle¬and other warm-blooded animals inhale the bacterial-laden aerosol. A state can lose its TB-free status if two infected herds are detected within a 48-month period.
“Beef heifers from states with less than TB-free status must be individually identified, before they enter Texas in feeding channels, but not consigned directly to a feedyard either through sale at a livestock or directly entering for pasturing on grass or wheat pastures. Beef heifers consigned to Texas for ‘breeding’ purposes must have a negative TB test within 60 days prior to entry, and these heifers will already be identified,” said Dr. Bob Hillman, Texas’ state veterinarian and executive director of the TAHC, the state’s livestock and poultry health regulatory agency.
Dr. Hillman explained that the individual identification (ID) can include an official ear tag, registration tattoo, registration brand, or an RFID radio frequency identification device. The identification information must be recorded on the certificate of veterinary inspection (or when traveling from New Mexico, a NM Livestock Inspection form), issued in the state of origin within 30 days prior to the animals’ movement.”
“By requiring beef heifers to be identified prior to arrival in Texas, they can be traced back to their herd in the originating state, if TB infection is detected in the animal. This could help protect Texas’ hard-earned TB-free status that was regained in October 2006,” he said.
USDA regulations require that beef breeding animals transported from non-TB-free states have a negative TB test within 60 days prior to movement, unless the animals are nursing a negative dam, or if the animals originate from a recognized accredited herd, which undergoes regular testing. Tested animals are provided with individual identification. The test results and identification must be recorded on the certificate of veterinary inspection (or NM Livestock Inspection form).
Since October 2007, the TAHC has had stringent TB entry requirements for dairy cattle. Due to their close confinement, dairy cattle have a greater risk of exposure to cattle TB, if an infected animal exists in the herd.
Dairy breeding cattle must have official ID and a certificate of veterinary inspection prior to entering Texas. Sexually intact dairy cattle older than two months of age must have a negative TB test within 60 days prior to entering Texas, unless they are being transported directly to slaughter or to an approved feedlot, then slaughter. Sexually intact dairy cattle younger than two months of age must hae an entry permit and are restricted to the premises of destination until they are tested negative for TB at the age of two months.
Mexican-origin (“M”-branded) steers recognized as potential rodeo and/or roping stock, and entering Texas from other states must have had a negative TB test within the previous 12 months and be accompanied by a certificate of veterinary inspection, issued within the previous 30 days.
The U.S. cattle TB eradication program began in 1917, when about five percent of the nation’s cattle herds were known to be infected. “Today, infection ‘makes news,’ and typically, fewer than a handful of infected animals are detected in a herd. However, all of the animals in the herd are considered to be exposed to the disease,” said Dr. Hillman. In addition to eradicating the disease in the herd, other practices to protect consumer health include pasteurization of milk to kill bacteria, and carcass inspection for wholesomeness at slaughter. Cooking meat also kills the TB organism.
Texas originally gained its TB-free status in 2000, but lost it in 2002. Nearly 2,800 Texas herds were tested before the state regained its ranking in October 2006. A veterinarian can test live cattle for TB by injecting a tiny amount of tuberculin into the animal’s skin near its tail, in an area called the “caudal fold.” Seventy-two hours later, the veterinarian will “read” the area, feeling for swelling, a lump or thickening indicative of a reaction to the tuberculin; an indication the animal may have been exposed to cattle TB bacteria.
Skin test “reactor” animals that also test positive to the gamma interferon blood test are destroyed, and their carcasses are carefully examined for internal lesions. Tissues collected are prepared and forwarded to the National Veterinary Service Laboratory (NVSL) in Ames, Iowa. If bacteria from the lesions are identified as Mycobacterium bovis (or M. bovis), the herd is considered to be infected and will be quarantined. The USDA will offer to purchase infected herds, to enable the producer to restock with TB-free animals, forgoing a long quarantine and retesting period that can last several years.
“Preventing the introduction of disease into a herd can be accomplished by testing newly purchased breeding animals,” urged Dr. Hillman. “Most importantly, avoid commingling untested feeder animals with valuable breeding stock, and do not mix domestic cattle with feeder and rodeo animals originating from Mexico, where higher rates of cattle TB are known to exist. Dairies should be especially careful to introduce only TB-tested cattle, as disease can spread more easily in the close confinement of these operations.”
Producers who have questions about importing to Texas are invited to call the TAHC’s permit desk at 800-550-8242, ext 777. A chart on cattle entry requirements can be viewed on the TAHC’s web site at http://www.tahc.state.tx.us.