USDA Orders Testing of Dairy Cattle
Published: Friday, May 3, 2024
The U.S. Department of Agriculture last week issued a nationwide order requiring testing of dairy cattle prior to interstate movement. The order took effect on Monday of this week and applies only to lactating dairy animals.
The Agriculture Department took this dramatic step after the highly pathogenic avian influenza (HPAI) H5N1 virus was found in 33 dairy herds across eight states, including Michigan.
In Indiana, State Veterinarian Dr. Bret Marsh held a conference call last Friday with state agriculture leaders. In his remarks, Marsh emphasized that, while there are no confirmed cases of the virus in the Hoosier state, officials are taking the situation seriously and urging producers to take every necessary precaution.
"Biosecurity is of the utmost importance," Marsh said.
Before dairy cattle can be moved out of state, they must have a negative test for Influenza A virus at an approved laboratory. In Indiana, the only approved laboratory is the Animal Disease Diagnostic Laboratory at Purdue University.
Another piece of the federal order is mandatory reporting of positive test results from laboratories and state veterinarians to USDA's Animal and Plant Health Inspection Service.
If there is a positive test, the herd owner will be required to provide epidemiological information, including animal movement tracing.
According to a USDA guidance document, the H5N1 virus can spread between:
• Cows within the same herd,
• From cows to poultry, and
• Between dairies associated with cattle movements.
Cows without clinical signs have tested positive, according to USDA.
The testing requirement involves the milk from lactating dairy cattle, not calves, pregnant or open heifers, or dry cows, Marsh said.
When asked why beef cattle aren't covered under the testing rule, Marsh said the virus thus far has shown a tendency to incubate in the mammary tissue of lactating dairy animals.
"This is an emerging disease in dairy cattle," Marsh said.
"On April 16, APHIS microbiologists identified a
shift in an H5N1 sample from a cow in Kansas that could indicate the virus has an adaptation to mammals," the USDA guidance document states.
The USDA document adds, "The novel movement of H5N1 between wild birds and dairy cows requires further testing and time to develop a critical understanding to support any future courses of action. This federal order is critical to increasing the information available for USDA. Requiring positive test reporting will help USDA better understand this disease and testing before interstate movement will limit its spread."
While two human cases of H5N1 have been reported, USDA said "we have not found changes to the virus that would make it more transmissible to humans and between people. While cases among humans in direct contact with infected animals are possible, our partners at the U.S. Centers for Disease Control and Prevention believe that the current risk to the public remains low."
Cows that test positive for Influenza A are not eligible for interstate movement for 30 days from the most recent collection of any sample that tests positive from any individual animal in the herd. After the 30-day period, animals must be tested again prior to movement.
Marsh encourages producers to be vigilant for signs of the virus in their herds.
"We have no diagnosis of this type on dairy farms in Indiana, although we encourage producers who see anything unusual or consistent with the clinical signs that have been described in other states, to please get with their veterinarians so we can get appropriate samples collected," he said. "But at least at this point, we will continue the inspections on dairy farms across the state."
Indiana has approximately 190,000 dairy cows and nearly 700 Grade A dairy farms.
Marsh added that the federal order probably would not affect many lactating dairy animals in Indiana.
"Based on our estimation, most of the lactating dairy cattle stay on a site during that lactation period, and only after they're dry (do) they move elsewhere," he said.
Last Saturday, USDA addressed question relating to the movement of cull cows to auction markets. In short, USDA's testing requirement is waived, he said, for non-clinical cows shipped to a sale barn or from a sale barn directly to a slaughter facility.
However, Marsh added that "clinical, lactating dairy cattle are ineligible for interstate movement or movement to slaughter."
According to Marsh, test samples can be collected by an accredited veterinarian, a licensed veterinarian or a collector who is approved by the state veterinarian.
Marsh said the costs for the lab tests will be picked up by USDA, but it remains unclear who will pay for the cost of collection and shipping, Marsh said.
"This is a very fluid discussion at this point," he said.
At the retail level, the U.S. Food and Drug Administration has conducted testing on milk samples and concluded that "pasteurization is effective in inactivating HPAI."
Marsh talked about the guidelines for the purchase and shipment of raw milk. He pointed out that raw milk cannot be sold for human consumption in Indiana, although some states allow it.
The FDA bans the shipment of raw milk across state lines—if that milk is intended for sale.
Indiana does not forbid the sale of raw milk, Marsh said, as long as the milk is labeled as pet food.
"We're communicating directly to those who have a pet food permit to make sure they understand the consequences and the potential risks, as we have done before, about consuming raw milk," Marsh said.
Return to Top of Page