Three of the major agricultural industries in the United States are beef cattle, ethanol production, and oilseed processing. The co-products of ethanol and oilseed processing are excellent feedstuffs for beef cattle, but there is still much to learn regarding the relative value of these feeds. Presently, we are witnessing 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 byproducts, and, if so, how could cattle producers take advantage? Our research group has shown that DDGS and solvent extract soybean meal (SBM) deliver a similar metabolizable AA in finishing diets, however, the apparent digestibility of arginine, lysine, methionine, and tryptophan was superior in SBM compared with DDGS. These AA are key for reproduction and lactation, therefore, the use of SBM may offer a metabolic advantage for the breeding herd. Arginine and methionine modulate utero-placental blood flow and support cell proliferation and gene expression in the growing fetus. Similarly, lysine optimizes N metabolism in the mammary gland and enhances milk protein synthesis. We hypothesize that this favorable AA profile would be further amplified in heat-treated soybeans due to its greater rumen undegradable protein (RUP) content compared with SBM. Thus, potentially impacting cow physiology and metabolism. Our research group then performed a pilot study evaluating extruded expelled soybean meal (EESBM) supplementation for beef cows. Supplements (DDGS or blend EESBM (55%) and soyhulls (45%)) were individually fed at a rate of 0.5% BW from 30 days pre-breeding (AI) up to 60 days post-breeding. Blood samples were collected at calving (d 0) and on days 35 and 65 post-calving. Preliminary data show greater blood creatinine (P = 0.02) and blood urea N (P < 0.01) for EESBM-supplemented cows, while concentrations of IGF1 tended to be lower (P = 0.08). This might indicate asynchrony between available carbohydrates and N in the rumen. Other soybean byproducts, such as soybean oil and soybean hulls also provide valuable evidence of the modulatory role of soybeans on cow physiology. Previous studies show that Ca salts of soybean oil during late gestation increase IgG concentrations in colostrum and gene expression of adipogenic and myogenic genes in the offspring. Additionally, it has been reported that soybean hull supplementation improved uterine blood flow and tended to increase milk yield. Overall, these results demonstrate that soybean byproducts can modulate maternal endocrine and physiological adaptation, providing clearer insight into their nutritional value.

Menezes, A. 2026. Soybean Byproducts on Beef Cow Nutrition: Potential Impacts on Metabolic and Physiological Parameters. ASAS Midwest Section Meeting. Abstract 226. https://doi.org/10.1093/jas/skag107.268