As harvest season approaches, nutritionists will be starting to make recommendations using the commodities the farmers have available to them. Soybeans serve as an essential source of rumen degradable protein, fat, and digestible fiber — all crucial to a dairy cow’s diet. For many years, farmers have used roasted soybeans as a protein source that can boost milk and milk protein yields. However, over the last few years, including roasted high-oleic soybeans in dairy rations has gained traction. In a Buckeye Dairy News article, The Ohio State University extension dairy specialist Maurice Eastridge discussed the process of roasting soybeans and the differences between high-oleic and conventional soybeans.

Processing soybeans allows for the oil to be either extracted or expelled. Hulls are then removed from the seed before extraction and can be used as feed for livestock or added back into soybean meal. As hulls are left separate, soybean meal’s crude protein level hovers around the 48% mark. If the hull is included in the meal, protein levels typically drop to about 44%. Whether conventional or high-oleic, whole soybeans range from 36% to 38% crude protein and have roughly 20% fat.

It is important to note that high-oleic soybeans are naturally high in oleic acid, a monounsaturated fatty acid. Conventional soybeans on the other hand, contain linoleic acid, a polyunsaturated fatty acid. “Polyunsaturated fatty acids are more likely to disrupt ruminal fermentation in dairy cows which may cause a decrease in feed intake, fiber digestibility, milk yield and/or milkfat concentration and yield,” noted Eastridge.

Typically, the cost of roasting soybeans is between $35 and $45 dollars a ton, equivalent to $1.20 per bushel. The dairy extension specialist listed some considerations to keep in mind when thinking about using roasted soybeans as a part of a dairy ration.

1. The temperature for roasting should be 290°F to 315°F. Then, the soybeans need to be steeped for 30 minutes or longer. Steeping is especially important if roasting occurs at the lower temperatures and with limited holding times within the roaster. Following roasting, beans will need to be cooled by pushing or pulling air through the beans.
2. Throughout the roasting process, expect there to be shrink. This is due to the loss of some moisture, hulls, and pod trash.
3. After roasting, the soybeans can be fed as ground or cracked. Prior Ohio State research found that soybeans fed in quarters or eighths improved digestibility compared to feeding whole soybeans.
4. Inclusion level in diets for lactating dairy cows range from 10% to 20%, depending on other ingredients in the diet, production levels in the cows, and protein target levels of unsaturated fat.

Whether conventional or high-oleic, roasted soybeans can bring many benefits to the table in terms of protein and milk yield. “Soybeans heated at too high of temperature or steeped too long can have reduced protein digestibility. Some laboratory results are available as indicators of underheating or overheating of soybeans, and these can be useful in monitoring processing methods, but they may not reflect what actually happens within the animal because of the impacts of rumination fermentation and rate of digesta passage,” Eastridge explained. It is important to make decisions that are farm-specific with the commodities that are available to help achieve success.