High oleic soybean interest grows

Feeding high oleic soybeans to dairy cows continues to gain interest across the Midwest, and several farms planted high oleic beans this spring for the first time. I first wrote on this topic in my January 2024 column. Since then, new research and practical experiences have furthered our knowledge.

Nutritional advantages of high oleic soybeans

Depending on how they are processed, soybeans and their byproducts can provide varying levels of high-quality protein and energy from fat. Historically, producers limited the amount of roasted conventional soybeans fed because their high levels of certain fatty acids can disrupt normal rumen function and alter rumen fermentation, leading to decreased milk fat.

While conventional and high oleic soybeans have similar protein and fat content, they differ in their fatty acid profiles. In conventional soybeans, less than 25% of the fat is comprised of oleic acid, and the remainder is comprised mostly of linoleic acid. In high oleic soybeans, the percentage of oleic acid is closer to 75% and less than 10% is linoleic acid. This higher concentration of oleic fatty acids is much more rumen-friendly, reducing the risk of milk fat depression.

High oleic soybean research updates

Most research on feeding high oleic soybeans to dairy cows has been conducted at Pennsylvania State University and Michigan State University. In March, I moderated a panel discussion at the Central Plains Dairy Expo, featuring Dr. Kevin Harvatine from Penn State and two dairy producers who have fed high oleic soybeans for 3-5 years. In June, during the Four State Dairy Nutrition and Management Conference in La Crosse, Wisconsin, Dr. Alica Bales shared some of her research conducted in Dr. Adam Lock’s lab at MSU.

Harvatine shared Penn State research comparing normal to high oleic ground roasted soybeans that showed higher milk fat concentration and higher fat yield. Bales highlighted MSU research that compared feeding rates of 0%, 8%, 16% and 24% of the total diet dry matter from high oleic soybeans. Results showed significantly higher milk yields and increased fat and protein yields, although there was a slight reduction in protein yield at the 24% feeding rate. Dry matter intake was lower for the higher feeding rates, resulting in improved feed efficiency.

Bales also shared research comparing roasted and raw soybeans at the 16% inclusion rate. The compelling results showed that roasting high oleic soybeans generated significantly higher milk and fat yield and a trend for increased protein yield compared to feeding raw high oleic soybeans. Bales commented that roasting does not alter the fatty acid profile of the soybean. She reiterated that heat-treating soybeans has the added benefits of increasing rumen undegradable protein within the soybean and inactivating the urease enzyme. Most commercial feed analysis labs will offer a test called protein dispersion index, which is a measurement to indicate whether soybeans are optimally heated. Target values are between 9 and 11; a value less than 9 indicates overheating and a value greater than 11 indicates underheating.

Feeding high oleic soybeans

The return on investment with high oleic soybeans will vary by farm, depending on feeding rates, current feed ingredients and feeding strategies. Typical feeding rates of high oleic roasted ground soybeans range from 3 to 8 pounds per cow per day, although both producers on the CPDE panel have experimented with higher feeding rates and noticed continued benefits. They only discontinued use because of inventory concerns. As mentioned previously, the MSU research also pushed higher levels with mostly positive results.

A common question is how finely to grind roasted high oleic soybeans for feeding purposes. This, too, can be somewhat farm-specific and dependent on dietary factors and desired feeding rate. MSU trials targeted 750 microns, but field experience has seen good results from grinds both coarser and finer than this. Both producers on the CPDE panel suggested their best performance occurred with a micron size slightly under this target value. Dr. Harvatine cautions that, if the soybean is processed too fine, the expanded surface area can reduce RUP due to higher ruminal digestion, thus reducing the bypass value gained through heating.

High oleic soybeans have been shown to be comparable to normal soybeans in terms of seed costs, with no difference in yields or protein and fat concentrations. In a few areas, crop producers raising high oleic soybeans have been able to contract for a premium over conventional soybeans.

Maturity options may be a challenge for northern locations, with 1.9 as the lowest maturity rating currently available. Weed control can also be a challenge with limited herbicide options. Future varieties will soon be available with traits that allow for controlling the weed populations.

The opportunity to feed a homegrown protein source is certainly attractive to farms with surplus land base. In addition, farms may have opportunities to further reduce purchase feed costs from conventional soybean meal, bypass protein and bypass fat sources. Work with your agronomist and nutritionist to determine if high oleic soybeans fit in your operation.

Barry Visser is a nutritionist for Vita Plus.