Safety and treatment strategies for manure foaming

Foam can pose significant challenges, ranging from increased emissions to potential safety hazards for both pigs and farm workers.

December 5, 2023

3 Min Read
National Pork Board

By Daniel Andersen, Iowa State University Agricultural and Biosystems Engineering

This past year there were more frequent reports of foam on swine manure storages. Historically, we have seen that late fall and winter are critical times for remembering safety principles, especially when the barn is empty during cold weather when ventilation is reduced.  A minimum ventilation rate of 1.8 CFM could result in a methane concentration of approximately half the explosive limit.

Swine manure foaming occurs when a combination of factors, including diet, microbial activity and environmental conditions, leads to the production of stable foam in manure storage. This foam can pose significant challenges, ranging from increased emissions to potential safety hazards for both pigs and farm workers. We recently released a six-page guide on the science of manure foam, what we know about causes, ways of treating foam, and ventilation recommendations.


Spontaneous foaming in swine manure storages is an ongoing challenge and has serious potential danger. Methane gas is trapped in the bubbles and creates the potential for fires and explosions, especially when the foam bubbles and/or during low/minimum ventilation. Hazardous conditions are during agitation, pumping, pressure washing, or activities like welding and hot work where slag might fall into the foam.

If you are experiencing foam, make sure you take the appropriate precautions to ensure safety for you, your employees, your pigs and the building.

  • Provide continuous ventilation to prevent gas build-up. Increase ventilation during agitation to quickly dissipate released gases.

  • Turn off heater pilot light and other non-ventilation electrical systems, such as the feeding system, that might produce an ignition spark.

The recently released guide outlines practical treatment strategies to address swine manure foaming. Topics in the incorporation of anti-foaming agents and careful monitoring of manure storage conditions. It is important to understand the factors that contribute to foaming, such as diet composition and microbial activity to effectively develop treatment plans. Regular assessments to identify potential foaming issues before they escalate are crucial for preventing environmental contamination and ensuring the well-being of the pigs.


Finding ways to reduce methane production leads to less foam. Strategies that reduce carbon in the manure lower the chance of foam formation by lowering the microbial food supply. This could be dietary changes towards more digestible feed ingredients (typically those lower in fiber content) or finding ways to make currently utilized components more digestible (including finer grinding or feed treatments to improve digestion).

Treatment with ionophores impacts the methane production pathways and has been shown to be effective. Skysis (Narasin) is a swine-safe additive, and our research, suggests rates in the manure of approximately 5 pounds per 100,000 gallons of manure. Similar compounds include Rumensin and Coban. Results indicated reduced methane production from treated manures for around 90 to 120 days.

Research has also shown treatments that destabilize the proteins, such as proteases, can significantly reduce foaming capacity and foaming stability. Other treatments that seed microbes, especially microbes known to produce proteases, into the manure may be a practical treatment.

If a treatment is performed to mitigate the foam, especially a treatment that breaks the foam and releases substantial methane quantities, ventilation rates should be increased to purge methane from the facility.

In conclusion, prioritize safety measures and adopt proactive strategies in the treatment of swine manure foaming. Farmers can enhance the sustainability and efficiency of their operations while safeguarding the health and safety of both livestock and farm personnel.

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