Avian Influenza Impacts U.S. Dairy Farms

Cornell Study Shows Virus Causes Severe Mastitis and Milk Loss

The recent outbreak of highly pathogenic avian influenza (HPAI) H5N1 has brought unexpected challenges to the U.S. dairy sector.

A Cornell University study shows that infected cows suffer from severe mastitis, lower milk production, and higher mortality rates, leading to significant losses for farmers.

Researchers tracked a herd of 3,876 cows in Ohio, finding that infected cows had a high risk of death or early removal. The economic impact was staggering—$950 per infected cow, totaling nearly $737,500 for just this herd.

Felipe Peña Mosca, a lead researcher, stated, “The farm did its best to isolate the affected animals,” yet the virus still spread rapidly, affecting 20% of the herd within just 23 days. Of the 777 infected cows, almost 40% left the herd within two months.

Virologist Diego Diel emphasized the financial burden, noting, “This represents a shock to production costs if you are affected by an outbreak.” Although pasteurization ensures milk safety, the production decline is a major setback for dairy farmers.

The study also revealed that common disinfection methods during milking could inadvertently help spread the virus. Traditional mastitis prevention strategies may not be effective against HPAI, raising concerns for dairy operations.

Detected first in wild birds in 2024, the virus’s spillover to cows triggered a new wave of research on food safety and animal health. The outbreak adds to the $1.4 billion cost already faced by the poultry industry.

Biosecurity remains a key challenge, especially for dairy farms with open housing systems. The researchers call for more studies on virus control and the development of effective vaccines to protect dairy herds.

This growing concern reinforces the need for constant vigilance and research to safeguard the future of America’s dairy industry.