Corn dry-milling co-products are a standard feed ingredient in North American feedlots. Cattle feeders adopted distillers and other corn processing co-products because of low cost, availability, and unique nutritional characteristics (high fat and protein with low starch) of these feedstuffs, at least initially. Consequently, oilseed meals have only rarely been included in cattle feeding diets during the last 20 years. Hence, there is nearly an entire generation of consulting nutritionists that have rarely used oilseed mills in diet formulations. However, market conditions are seldom static and conventional wisdom regarding feedstuff usage needs to be continually tested against changing conditions. Changes in bio-fuel market demand result in altered supply of processing co-products. In addition, genetic potential for growth in feedlot cattle has dramatically increased, meaning that quality and quantity of metabolizable protein requirements may be different compared to when corn processing co-products were first introduced. There is a critical need for an updated comparison of distillers grains with oilseed meal using modern cattle genetics to provide cattle feeders with the best data to drive decision making under dynamic market conditions.

The objective of this experiment is to examine the effects of soybean meal with or without additional soybean hulls in replacement of modified corn distillers grains plus solubles on growth performance, efficiency of dietary net energy utilization, and carcass trait responses in finishing beef steers.

We will generate two abstracts for national meetings and one peer-reviewed manuscript from this research. This will project will also partially fulfill degree requirements for one graduate student. In addition, this data will be presented through multiple Extension and allied industry channels.

Updated October 17, 2022:
We initiated the experiment on September 20, 2022. There are 240 steers in 24 pens on test at the Southeast Research Farm located near Beresford, SD. Initial shrunk weight of the steers was 959 pounds. There are three treatments in this experiment (eight pens per treatment, 10 steers per pen). The treatments are a control where modified distillers are used as the source of supplemental protein, compared to a second treatment where soybean meal and corn replace distillers, and a third where soybean meal and soybean hulls replace distillers grains. All diets are equivalent in crude protein; the control and soybean meal/soyhull diets are equivalent in Neutral Detergent Fiber (NDF) content. We expect to ship these steers for harvest in January of 2023.

Updated January 30, 2023:
We initiated this study on September 20th using 240 Angus steers. These cattle had an initial weight of 959 pounds. Steers were allocated to one of three treatments. Those treatments were: Control diet where the primary protein source on a DM basis was 15% modified distillers grains (MDGS) with the balance of the diet 71% dry rolled corn, 10% ryelage, and 4% liquid supplement (DM diet composition 14.1% crude protein and 17.3% neutral detergent fiber0; a soybean meal (SBM) based diet where the 15% MDGS was replaced by 9% soybean meal and 6% dry rolled corn (DM diet composition 14.2% crude protein and 14.1% neutral detergent fiber); and a soybean meal – soyhull (SBMSH) based diet where the 15% MDGS was replaced by 9% soybean meal and 6% soyhulls (DM diet composition 14.3% crude protein and 17.3% neutral detergent fiber). We formulated the diet so that all three were essentially equivalent in crude protein (CP) and that CON and SBMSH were equivalent in percentage neutral detergent fiber (NDF).

These steers were purchased from a central SD livestock auction seven days prior to study initiation. After arrival at the Southeast Research Farm, steers were weighed, individually identified, vaccinated against respiratory and clostridial diseases, and treated for internal and external parasites. On September 20th, steers were weighed and allotted to their treatment pens (n = 8 pens per treatment, 10 steers per pen). Steers were weighed again 21 days after study initiation and implanted with a steroidal growth-promoting implant containing 200 mg trenbolone acetate and 28 mg estradiol benzoate. Steers were weighed again at 28-d intervals.

We weighed the steers for the final time on d 118 (January 16, 2023). Later that day they were loaded onto trucks and shipped to the harvest facility in Dakota City, NE. The steers were harvested the next day at which time we confirmed animal identification to match against the camera data provided by the harvest facility and evaluate livers for the presence and severity of abscesses.

We are still completing analysis of weekly ingredient samples. We do have preliminary performance and carcass data to report (Table 1). Two steers were removed from the study for reasons unrelated to dietary treatment; consequently, all results are reported on a deads and removals excluded basis. The initial and d 21 body weights reported were shrunk by 4% to account for gut fill. The final weight reported was calculated by dividing hot carcass weight (HCW) by 0.625.
During the first 21 days, SBM and SBMSH steers gained faster and more efficiently compared to MDGS (P = 0.01). We were not expecting this result and currently do not have a satisfactory explanation for these differences. It is possible that protein from soybean meal was higher quality and better able to support lean muscle accretion in yearling steers demonstrating compensatory gain. There may be other explanations, such as transitory differences in water intake or gut fill.

The differences between treatments largely disappeared by the conclusion of the study. On a carcass-weight adjusted basis, ADG, dry matter intake, and feed efficiency were unaffected by treatment (P = 0.11), although there was a weak tendency for increased final body weight in the MDGS treatment (P = 0.09) compared to the two treatments feeding soybean meal. Steers in the MDGS treatment also had approximately 0.75% greater dressing percentage (P = 0.05) and tended to have greater rib eye area (REA; P = 0.07) compared to the soybean meal treatments, but USDA Yield Grade was unaffected by treatment (P = 0.47). Distributions of USDA Quality and Yield Grades were unaffected by treatment (P = 0.39). Feeding different sources of supplemental protein also had no effect on the incidence or severity of liver abscesses (P = 0.11).

We will be completing the analysis of the nutrient composition of weekly ingredient samples in the next month. These results will be presented as a poster at the Plains Nutrition Council meeting in San Antonio, TX in April and will be submitted as an abstract to the National Animal Science meetings held later this summer. This work will ultimately be part of a MS student’s thesis (Cassidy Ross) and be submitted for publication in a peer-reviewed scientific journal that is well-recognized in feedlot nutrition circles. We will also be disseminating this data through SDSU Extension channels.

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Updated April 28, 2023:
Results of this study were presented at the Plains Nutrition Council in San Antonio, TX April 5 - 7, 2023. This meeting hosts feedlot researchers from across the United States and Canada as well as professional nutritionists who advise the feeding of more than 90% of the feedlot cattle in North America. A copy of the poster presented by Cassidy Ross (MS student supported by this project) is attached as well as the abstract submitted as part of the conference proceedings.

We will be presenting this data at the National Animal Science meetings in Albuquerque, NM in July 2024. We will be completing and diet nutrient analysis within the next eight weeks. At that time we will complete the final report and include these data in materials disseminated to the cattle feeder and soybean producer audiences.

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Updated July 29, 2023:
Cassidy Ross presented the results of this study at the American Society of Animal Sciences Annual Meeting in Albuquerque, NM on July 17th. She will be preparing a manuscript for publication in a scientific journal over the next ten months as she completes her Master's degree in Animal Science. In addition, we published a lay summary of this research on the SDSU Extension website (https://extension.sdstate.edu/comparing-soybean-meal-distillers-grains-finishing-cattle). These results were also the subject of a radio segment heard by farmers and ranchers across South Dakota.

View uploaded report

Updated July 29, 2023:
Cassidy Ross presented the results of this study at the American Society of Animal Sciences Annual Meeting in Albuquerque, NM on July 17th. She will be preparing a manuscript for publication in a scientific journal over the next ten months as she completes her Master's degree in Animal Science. In addition, we published a lay summary of this research on the SDSU Extension website (https://extension.sdstate.edu/comparing-soybean-meal-distillers-grains-finishing-cattle). These results were also the subject of a radio segment heard by farmers and ranchers across South Dakota.

Comparing Soybean Meal to Distillers Grains for Finishing Cattle

Key Points
• There were no differences in performance or feed efficiency when yearling steers were fed diets using distillers grains, soybean meal, or soybean meal with soyhulls.
• In this experiment, feeding modified distillers grains provided no added benefit when high-moisture roughage sources were used in the diet.
• Based on these results, supplemental protein sources should be evaluated on the cost per delivered unit of crude protein.

For the last 20 years, co-products from corn processing have been the primary source of supplemental crude protein for cattle feeders. Expanded ethanol production in South Dakota and the surrounding region resulted in plentiful supplies of competitively priced distillers grains, allowing feeders to formulate diets at a lower cost of gain. In addition, the added ruminally undegradable protein from distillers grains and the bunk conditioning attributes of wet or modified distillers provided nutritional and feeding benefits. So, it is no surprise that distillers grains have been included in virtually all cattle diets in recent memory. Many feeders and nutritionists have never actually fed diets that did not contain corn processing co-products.

COVID, and the fuel/transportation issues triggered by that pandemic, began to shift the assumption that distillers grain was the sole option. Distiller grains production is intrinsically linked to ethanol output, so as demand for ethanol decreased, so did distillers production. At the same time, we witnessed increased oilseed demand brought about by greater demand for renewable diesel fuel. Consequently, soybean crush capacity is dramatically increasing. Will greater crush capacity result in more plentiful, less expensive soybean meal, and if so, how could cattle feeders take advantage of these opportunities.

We conducted an experiment sponsored by the South Dakota Soybean Research and Promotion Council in 2022 to compare soybean meal and soyhulls to distillers grains with the objective of determining if there were performance differences caused by different protein sources. We used three different diets; a standard Midwest finishing diet using modified distillers grain, a diet where we substituted soybean meal for corn and distillers, and a third diet where we substituted soybean meal and soyhulls for distillers. All diets had the same crude protein content and the diet with soyhulls had the same amount of fiber as the distillers-based control diet. We conducted the study at the Southeast Research Farm near Beresford using 240 yearling steers with an initial weight of 959 pounds for 118 days.

We found that there were no appreciable differences in cattle performance, feed efficiency, or carcass characteristics between yearling steers fed different protein sources. Dry matter intakes for the control diet, soybean meal, and soybean meal plus soyhulls were 29.1, 29.3, and 27.1 pounds, respectively. Average daily gains followed a similar pattern with the final results being 4.61, 4.59, and 4.43 pounds per day for the three respective treatments. Feed efficiency values (feed to gain) were 6.29, 6.41, and 6.58 for control, soybean meal, and soybean meal plus soyhulls. None of these performance results were statistically different. We do not have a good explanation as to why the soyhull treatment ate numerically less feed. Distributions of USDA Quality grades did not differ in this study, resulting in no difference in carcass value because of dietary treatment.

Source of protein made only a trivial difference in this study. There was no inherent advantage to including modified distillers in a cattle finishing diet under these conditions. Based on these results, we conclude that cattle feeders should base protein supplement decisions on delivered cost per unit of crude protein and feed handling capabilities of individual yards.

There are approximately 1.8 million growing and finishing cattle on feed in all of South Dakota and the area contained in a 150-mile radius of Sioux Falls. If soybean meal was included at 2.5 pounds per day fed to only 25% of the regional cattle inventory, total disappearance would equal approximately 205,000 tons annually compared to current conditions, representing an entirely new market opportunity. The geographical locations of current and proposed soybean processing facilities in South Dakota are well-positioned to help supply some of this potential demand as they are located in the heart of the SD cattle backgrounding and finishing region and close to major cattle feeding areas of surrounding states.