StoneX logo

California Dairy Farms Face Outbreak of Avian Flu in Cow Herds

Key takeaways

  • Avian flu is spreading across dairy cows in California
  • More than 500 herds may be infected by early December
  • StoneX’s Nate Donnay suggests output could fall through November

Bloomberg News reports that California is currently facing an outbreak of avian flu in cattle, which has infected dozens of dairy herds and continues to spread. Nate Donnay, director of dairy market insights at StoneX Group, offered his insight into the worsening situation, saying the disease is not yet under control and more herds may become infected in the coming months.

A cattle vaccine is “probably the way that we dramatically slow the spread and really keep it from getting a bigger foothold in other parts of the country,” Donnay said. “But in the short term, once it shows up in one of these major dairy areas with large dairy farms, it just seems to spread like wildfire.”

According to Federal health officials, the risk to the general public remains low. Fifteen people in California have tested positive after being exposed to sick cows, according to the Centers for Disease Control and Prevention.

California produces more milk than any other US state. The outbreak, which started in March, hasn’t led to supply shortages so far; and the impact, apart from the rendering of deceased carcasses, has been minimal. Experts have said that this will likely change if the disease keeps spreading.

Farmers are under increased pressure, staining resources to treat sick animals, and going as far as culling cows that can’t produce as they could before becoming infected. An October heat wave likely worsened the illness in the sick animals, exacerbated fevers and dehydration.

The US Department of Agriculture stated that California’s milk production in September changed little from the prior year. Donnay said output could fall 1% to 3% through November, similar to that experienced by other states.

California’s dairy industry has managed the outbreak better than other states despite the high number of cases because it had time to prepare better testing and treatment. 

Make actionable Dairy Insight Your Edge

Navigate volatile dairy markets with confidence. Try StoneX Plus free for 14 days. Access expert analysis, forecasts, and customizable data tools to drive smarter decisions. From live prices to interactive charts, get the intelligence you need to thrive in today's volatile dairy markets.

Start Your Trial


To read the original article, click here.

Satellite view of Earth at night showing illuminated cities across Asia and the Middle East

See why StoneX is a partner of choice

Have questions about our products or services? We're ready to help.

StoneX: We open markets

Our market expertise, advanced platforms, global reach, culture of full transparency and commitment to our clients’ success all set us apart in the financial marketplace.

Reach

With access to 40+ derivatives exchanges, 180+ foreign exchange markets, nearly every global securities marketplace and numerous bi-lateral liquidity venues, StoneX’s digital network and deep relationships can take clients anywhere they want to go.

Transparency

As a publicly traded company meeting the highest standards of regulatory compliance in the markets we serve, our financials and record of accomplishment are matters of public record. StoneX’s commitment to “doing the right thing over the easy thing” sets us apart in the industry and helps us build respect, client trust and new partnerships.

Expertise

From our proprietary Market Intelligence platform, to “boots on the ground” expertise from award-winning traders and professionals, we connect our clients directly to actionable insights they can use to make more informed decisions and achieve their goals in the global markets.

© 2026 StoneX Group Inc. all rights reserved.

The subsidiaries of StoneX Group Inc. provide financial products and services, including, but not limited to, physical commodities, securities, clearing, global payments, risk management, asset management, foreign exchange, and exchange-traded and over-the-counter derivatives. These financial products and services are offered in accordance with the applicable laws in the jurisdictions in which they are provided and are subject to specific terms, conditions, and restrictions contained in the terms of business applicable to each such offering. Not all products and services are available in all countries. The products and services offered by the StoneX Group of companies involve risk of loss and may not be suitable for all investors. Full Disclaimer.

This website is not intended for residents of any particular country, and the information herein is not advice nor a recommendation to trade nor does it constitute an offer or solicitation to buy or sell any financial product or service, by any person or entity in any jurisdiction or country where such distribution or use would be contrary to local law or regulation. Please refer to the Regulatory Disclosure section for entity-specific disclosures.

No part of this material may be copied, photocopied or duplicated in any form by any means or redistributed without the prior written consent of StoneX Group Inc. The information herein is provided for informational purposes only. This information is provided on an ‘as-is’ basis and may contain statements and opinions of the StoneX Group of companies as well as excerpts and/or information from public sources and third parties and no warranty, whether express or implied, is given as to its completeness or accuracy. Each company within the StoneX Group of companies (on its own behalf and on behalf of its directors, employees and agents) disclaims any and all liability as well as any third-party claim that may arise from the accuracy and/or completeness of the information detailed herein, as well as the use of or reliance on this information by the recipient, any member of its group or any third party.