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U.S. Department of Agriculture detects second bird flu strain in dairy cattle

U.S. dairy cattle tested positive for a strain of bird flu that previously had not been seen in cows, the U.S. Department of Agriculture said on Wednesday, ramping up concerns about the persistent spread of the virus.

The H5N1 virus has reduced milk output in cattle, pushed up egg prices by wiping out millions of hens, and infected nearly 70 people since April as it has spread across the country.

Genome sequencing of milk from Nevada identified the different strain, known as the D1.1 genotype, in dairy cows for the first time, the USDA said. Previously, all 957 bird flu infections among dairy herds reported since last March had been caused by another strain, the B3.13 genotype, according to the agency.

Reuters reported news of the detection of the second strain on Wednesday ahead of USDA’s announcement.

The second strain was the predominant genotype among wild birds this past fall and winter and has also been found in poultry, the USDA said. It was identified in dairy cattle through an agency program that began testing milk for bird flu in December.

“We’re seeing the H5N1 virus itself be smarter than all of us,” said Beth Thompson, South Dakota’s state veterinarian.

“It’s modifying itself so it’s not just staying in the poultry and the wild waterfowl. It’s picking up a home in the mammals.”

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Alternatives to Antibiotics - Dr. Luciana Rossi

Video: Alternatives to Antibiotics - Dr. Luciana Rossi



In this special re-run episode of The Swine Nutrition Blackbelt Podcast, we bring back our conversation with Dr. Luciana Rossi, Associate Professor at the University of Milan, who discusses alternatives to antibiotics in swine nutrition. She explores antimicrobial resistance, the role of functional ingredients, and the potential of biochar in improving gut health and sustainability. Tune in now on all major platforms!

"Biochar, a vegetable charcoal produced by pyrolysis, has shown potential in reducing diarrhea incidence and improving gut health in weaning piglets."

Meet the guest: Dr. Luciana Rossi https://www.linkedin.com/in/luciana-r... is an Associate Professor at the University of Milan, specializing in animal nutrition, biotechnology, and innovative feed strategies. Her work focuses on functional ingredients, edible vaccines, and alternatives to antimicrobials to improve swine health and sustainability. Her research advances nutritional solutions that reduce disease risk and environmental impact.