New research from the University of Wisconsin–Madison Division of Extension is shedding light on how dairy producers can get the most from soybeans roasted on-farm. The study, authored by Jackie McCarville and Katelyn Goldsmith, outlines the key steps to improve soybean protein quality, enhance digestibility, and protect feed value.
Why Roasting Matters
Soybeans are a valuable source of both protein and fat in dairy rations. When roasted correctly, their rumen undegradable protein (RUP) content increases significantly — meaning more protein passes through the rumen and becomes available for absorption in the small intestine. Roasting also helps deactivate anti-nutritional enzymes and makes the fats in soybeans more accessible for energy production.
The researchers note that roasting increases RUP content from roughly 25% to 40–60%, improving the efficiency of protein use and supporting higher milk yields.
Getting the Process Right
The study emphasizes that proper roasting isn’t just about heat — it’s about balance.
Key steps include:
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Heating beans to 295–300°F to maximize protein quality and deactivate enzymes.
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Steeping for 30 minutes after roasting to allow even heat distribution.
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Cooling with aeration before storage to prevent spoilage.
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Storing in dry, debris-free bins below 60°F in warm months and 45°F in cold months.
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Processing by cracking or grinding to improve digestibility.
Following these steps helps prevent under- or over-heating, which can reduce feed efficiency and affect milk components.
Testing for Quality
McCarville and Goldsmith recommend producers test roasted soybeans to confirm optimal results. Common lab tests include:
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Protein Dispersibility Index (PDI): Should range between 9–12.
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Urease Activity: Indicates proper enzyme deactivation.
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In situ or in vitro RUP tests: Estimate how much protein remains available after digestion.
These tests help identify roasting inconsistencies and ensure feed performance aligns with expectations.
On-Farm Value
Properly roasted soybeans can reduce purchased protein costs and improve ration balance. However, McCarville and Goldsmith caution that the process requires attention to detail. Overheated beans can lose amino acid quality, while underheated beans may not deactivate anti-nutritional factors.
“Following best practices for on-farm roasting — including heating, steeping, cooling, storing, and processing — is essential for optimal results,” the authors conclude. “Testing remains an important quality control step to protect feed value and herd performance.”
Learn More
The full research article, “Best Practices for Roasting Soybeans on Farm for Dairy Diets,” is available through the University of Wisconsin–Madison Division of Extension Dairy Program.
Source: University of Wisconsin–Madison Division of Extension. “Best Practices for Roasting Soybeans on Farm for Dairy Diets.” Written by Jackie McCarville and Katelyn Goldsmith, 2025.
