Dr. Alex Hamberg, Pennsylvania State Veterinarian, recently discussed the guidance document released by USDA-APHIS that outlines the new federal order for livestock movement during the current HPAI outbreak in dairy cattle.

“The new federal order requires testing of cattle moving between all states, not just states with current cases,” said Hamberg. “Pre-movement testing is required for lactating dairy cattle within seven days of interstate movement. The federal order does not require testing cattle moving directly to slaughter.”

Cattle moving directly from the farm to the slaughter plant do not have to be tested, but if there is a livestock market or sale barn between the farm and harvest, testing is required.

Non-lactating dairy cattle includes heifers, dry cows and cull cows. However, testing is required for non-lactating animals greater than one year of age that are not going to immediate slaughter and are coming from a state with active cases.

Hamberg explained that prior to interstate movement, lactating dairy cattle are required to have a negative test for influenza A virus at an approved national health laboratory using a NAHMS (National Animal Health Monitoring System) approved assay. USDA will reimburse cattle owners for the cost of all pre-movement testing. The cost of collection is not reimbursed.

Pre-movement testing also applies to animals moving for the purpose of exhibition, so any lactating cattle moving across state lines for a show must require tested.

Samples must be collected by an accredited veterinarian, a state-licensed veterinarian or a sample collector approved by the appropriate state animal health official. Hamberg said an accredited vet who is currently working with a dairy can train designated personnel on that farm to collect milk samples and nasal swabs and package samples for submission.

For groups of 30 or fewer animals moving interstate, all animals must be tested. If more than 30 animals are moving interstate, then only 30 animals in total must be tested. This is an important consideration for those moving large groups.

Hamberg mentioned two new FDA regulations: electronic ID tags will be required for all sexually intact cattle and bison 18 months and older for interstate movement.

This is “for all dairy cattle, and cattle and bison of any age used for rodeo or recreation events and cattle and bison of any age used for shows or exhibition,” he said. “The rule requires official ear tags to be visually and electronically readable for official use for interstate movement of certain cattle and bison.”

The new rule also revises and clarifies certain recordkeeping requirements related to cattle. The rule will be in effect 180 days after it’s published in the Federal Register.

USDA issues cattle movement guidance

For testing purposes, a dry cow is defined “as if the last milking was so recent that the cow is still dripping milk, she’s lactating … If milk can be stripped easily, it’s a lactating cow,” Hamberg said. “Use common sense. A heifer bagging up may be considered a cow if she is dripping milk.” If in doubt, it’s best to test.

At sale barns, lactating cows purchased by out-of-state buyers must be held and tested. Ideally, lactating cattle would be tested prior to leaving the farm so they don’t have to be held.

In general, everyone involved in animal movement across state lines will also be involved in testing, such as a packer/buyer who will likely want tests on animals. The problem is that it’s impractical to test every lactating animal going to sale without knowing which will be purchased by an in-state or out-of-state buyer.

However, if a lactating animal is purchased by an out-of-state buyer and hasn’t been tested, there will be a waiting time for the test to be completed. Since USDA is reimbursing testing costs, it makes sense for the seller to test all animals prior to any movement to a sale barn.

Since the virus has been detected in farm cats, the cost of testing any dead cats on a dairy farm will also be covered, as well as testing prior to export.

If a farm property has both poultry and dairy cattle, surveillance and farm biosecurity should be even more rigid.

There’s still a question regarding virus transmission by non-lactating cattle: “What we know is that the milk from infected cattle seems to have the highest amount of virus in it,” said Hamberg. “There is less virus, if any, in other tissue. We aren’t sure how it is being transmitted but milk is likely the main transmission, likely via fomites – inanimate objects that are contaminated by infected milk” or other animals.

Fomites can be boots, boot covers, farm equipment, a number of other items and/or rodents.

If any cattle on a dairy farm test positive, can that farm spread manure? Hamberg explained that manure from positive poultry is full of HPAI virus because the virus affects all tissue in poultry. Cattle don’t have the same levels of virus in other tissue, so manure is less of a risk factor. However, if milk from infected cows is dumped into a lagoon, manure might be a concern.

The threat of feral swine spreading HPAI is another concern. “Swine have receptors for both mammalian and avian influenzas,” said Hamberg. “Swine are also typically susceptible to influenza A. The current HPAI strain is an influenza A.”

He suggested pig producers ramp up biosecurity, especially if there are poultry or wild birds on the premises.

by Sally Colby