Research Highlights

Re-Introducing Soybean Meal into Cattle Diets

By Carol Brown

Decades ago, soybean meal was a main ingredient in feedlot cattle diets. Today, because of the large biofuel market, most feedlot cattle diets include distillers grains, a co-product of ethanol production, and soy meal is not on the table. With the increase in biodiesel production, its co-product, soybean meal, is now more plentiful and available for cattle feed. But does it perform as well?

Warren Rusche, an extension beef feedlot management specialist at South Dakota State University, is revisiting the use of soy meal in feedlot cattle diets. Through a research project supported by the South Dakota Soybean Checkoff, he is comparing feeds that include soybean meal, with and without hulls, to those made with modified distillers grains. 

“Prior to the biofuel revolution, cattle feed included soybean meal and urea because it was inexpensive and they could convert its nutrients into protein,” explains Rusche. “After biofuels came along, the industry switched to distillers grains. There is at least a whole generation of cattle feeders who have never used something other than a corn processing co-product to feed their livestock.”

When the COVID pandemic hit and the ethanol plants shut down, distillers grains were suddenly unavailable, and Rusche says feeders had to scramble to reformulate diets. At nearly the same time, the renewable diesel fuel market and soybean crush capacity expanded, which led him to take another look at feeding cattle soybean meal.

“Over the years, cattle genetics have changed and we take them to a different endpoint now,” he says. “They have much greater capacity for growth and they usually finish at a heavier weight. We thought it was time to revisit an old ingredient for use in newer cattle production systems.”

In September 2022, Rusche and his colleague Zachary Smith, SDSU animal science assistant professor, placed 240 steers on one of three different finishing diets: modified, or wet, distillers grains as the control diet; soybean meal with corn, replacing distillers grains; and soybean meal with soy hulls to replace distillers grains. The steers had been range-grazing prior to being placed on these new feeds. They formulated all the diets to have the same protein content, and two of the diets had the same fiber content. The third diet included soybean hull pellets to match the amount of fiber in the distillers grains treatment. 

“One of the things we examined was whether feeding cattle more starch — which comes from feeding additional corn plus the soy meal to replace the distillers grains — affects outcomes such as growth rate, meat quality and grade, liver abscess, and more,” he says. “We slaughtered the cattle in January and found there were no real differences between the three feed treatments. It made no difference in terms of livestock efficiency and performance between the soy meal and the distillers grains.”

Rusche is conducting follow-up work and tweaking parts of the study to find why a few anomalies occurred. He and Smith are also conducting a study on cattle feed that blends distillers grains with soybean meal, funded by the Minnesota Soybean Research and Promotion Council. In another project funded by the South Dakota Soybean Checkoff, the team is looking at an expeller-processed soybean meal compared with conventional distillers grains. 

As Rusche demonstrates through these projects that soy meal is an equivalent option for cattle feed, an old standby could become the custom again.

“We are in an exciting time in terms of ruminant nutrition research, exploring a different class of feed ingredients,” Rusche comments. “Many people are looking at soybean meal again, as they did in the 1980s — everything old is new again.”

Published: Jun 26, 2023