Nathan Brearley’s dairy herd is still recovering six months after an infection.

With a closed herd and all his heifers artificially inseminated — no outside bulls needed — Nathan Brearley was confident his 500-cow dairy farm in Portland, Mich., would be spared from the avian flu strain that’s affecting dairies.

He was wrong. Nearly six months later after an infection on his farm, milk production still hasn’t recovered.

“I was quite surprised. I never saw any other disease this widespread affect the cattle like it did,” Brearley said during a recent webinar on dairy avian flu, put on by the Pennsylvania Center for Dairy Excellence.

With 29 confirmed cases — the latest being Sept. 9 — Michigan’s dairy industry has been one of the hardest hit by avian flu, H5N1, which was first confirmed in a Texas dairy in March.

Brearley said the first signs of problems were in April when the SmaxTec boluses in his cows, which keep track of temperature and other health parameters, started sending high-temperature alarms to his phone and computer. Half the herd looked like it was getting sick.

“Looking at data, the average temperature rise was 5.1 degrees above normal,” he said. “Outlying cows were even higher with temperature.”

The cows were lethargic and didn’t move. Water consumption dropped from 40 gallons to 5 gallons a day. He gave his cows aspirin twice a day, increased the amount of water they were getting and gave injections of vitamins for three days.

Five percent of the herd had to be culled.

“They didn’t want to get up, they didn’t want to drink, and they got very dehydrated,” Brearley said, adding that his crew worked around the clock to treat nearly 300 cows twice a day. “There is no time to think about testing when it hits. You have to treat it. You have sick cows, and that’s our job is to take care of them.”

Testing eventually revealed that his cows did indeed contract H5N1. But how they contracted it, he said, is still a mystery.

Brearley said an egg-laying facility a mile and a half away tested positive for H5N1 and had to depopulate millions of birds. The birds were composted in windrows outside the facility, “and I could smell that process.”

Whether the disease moved from that farm to his has not been confirmed, but multiple farms in his neighborhood also tested positive for the disease, Brearley said.

Production still lagging

The farm averaged 95-100 pounds of milk per head with 4.0% butterfat and strong solids before the outbreak. During the first three weeks of infection, milk production fell to 75 pounds a head and has been slow to recover.

“Honestly, we haven’t recovered since, though my forages have been stable,” Brearley said. “I cannot get back to our baseline again.”

Reproduction was also challenged. Right off the bat, his cows aborted their calves.

Brearley said he has reached out to industry people to see if the data from his cows can help answer how the disease spreads and its potential long-term effects on animals.

“I wanted to learn about it to help the industry just because of how sick these cows got,” he said. “I was very surprised we got it because we don’t move cows around.”

Voluntary testing needed

To date, no dairy farms in Pennsylvania have tested positive for H5N1, although the state was hit hard by H5N1 in poultry.

Alex Hamberg, state veterinarian for Pennsylvania, said very few dairy farms are participating in the state’s voluntary lactating dairy cow monitoring program. He said at least 400 dairy farms are needed to provide viable statistics on testing and to track where a disease outbreak could be occurring.

The Centers for Disease Control and Prevention is ramping up its own avian flu surveillance by testing wastewater facilities in Philadelphia and Harrisburg. Hamberg said the surveillance program will increase to 30 wastewater treatment plants statewide by the end of the year.

Rod Hissong, owner of Mercer Vu Farms in Mercersburg, Pa., is sharing disease surveillance data with the state. Like Brearley, Hissong has a closed herd — all replacement animals are bred in-house. But he also runs a second dairy farm in nearby Virginia where heifers are sent.

Because of the constant movement of cows and his proximity to other states, Hissong believes his farm is a prime target for infection. He tests his cows that go to and come from Virginia and does bulk tank milk sampling.

But there is another reason he does testing: There is a large egg-laying facility near his Mercersburg farm.

“And we do quite a bit of business back and forth with them,” he said. “For our security, their security, being able to have some testing and share it back and forth is crucial. And if there is an outbreak, we want to know about it.”

Hissong admits his farm, and the dairy industry itself, have been “lazy” when it comes to biosecurity. “Honestly, we are at a pretty elementary level of implementation. But testing is at least a start, and then we can ratchet it up,” he said. “We certainly didn’t want to be the ones responsible for bringing influenza into Pennsylvania.”

Lessons learned

Brearley’s testing regime consists of weekly bulk tank sampling and monthly all-cow sampling.

Now that the worst is over, he said there are things he would do differently.

“I would probably push more water to sick cows, and maybe put some electrolytes in the water,” Brearley said. “I would be set up better to not [have to] manually pump cows with a hand pump, and have that preset to fill cows with water.”

He didn’t test his cows until two weeks after the first high temperatures entered his herd, fearing that his milk processor wouldn’t accept his farm’s milk.

He estimates the outbreak cost him $100,000 in losses and extra labor costs. But the long-term effect on his animals is unknown.

Symptoms and prevention

Look for reduced milk production; thicker, concentrated, colostrum‐like milk; a decrease in feed consumption; abnormal, tacky or loose feces; lethargy; dehydration; and fever.

Cornell University recommends the following steps to protect your dairy: