Year 3: Mitigation of Fescue Toxicosis with Soybeans

Project Summary: The objectives of this proposal are to determine: 1) the effects of soybean hull, whole soybean, soybean meal supplementation during fescue toxicosis on plasma amino acid bioavailability, 2) the effects of soybean hull, whole soybean, soybean meal supplementation during fescue toxicosis on plasma isoflavone bioavailability, 3) the effects of soy isoflavones, soy amino acids, or their combination during fescue toxicosis on plasma amino acid bioavailability, and 4) the effects of soy isoflavones, soy amino acids, or their combination during fescue toxicosis on plasma isoflavone bioavailability. Benefit to Soybean Growers: Fescue toxicosis, caused by the consumption of ergot alkaloids from toxic endophyte- injected tall fescue, decreases the weaning weight of over 9 million beef calves in the Southeastern United States every year. This decrease in productivity translates to a $2 billion loss in economic revenue for the beef industry annually. There are few solutions that are both economically feasible and effective in treating fescue toxicosis. Recent research demonstrated that soybean meal mitigated ergot alkaloid vasoconstriction in goats and beef cattle. While soy products are common in swine and poultry livestock diets, the beef industry accounts for only 6.8% of soybean meal use. The unique profile of bioactive compounds in soybean (isoflavones and amino acids) could be the biological explanation for reducing fescue toxicosis and be used as a new marketing strategy to sell soybean co-products to beef producers. If all calves consuming fescue were supplemented with 1.5 lbs/d of a soy co-product to prevent fescue toxicosis, it would result in an extra 13.5 million lbs/d of soy co-products fed to cattle. Economic Impact: Beef cattle consuming tall fescue are typically supplemented with corn, distillers grains, or blends of co-products. However, other supplements do not contain the same bioactive compounds, such as isoflavones and essential amino acids, that are found in soy co- products. The low usage (6.8%) of soy co-products by the beef industry presents a huge opportunity to increase soybean utilization in beef cattle diets. The bioactive compounds in soy co-products are ideal to mitigate symptoms of fescue toxicosis and thus, could present a new market for soybean farmers to sell their products. We estimate that cattle consuming fescue (15 lb/d) would consume approximately 10% as soy coproducts (1.5 lb/d). If 9 million beef calves consuming tall fescue were supplemented with 1.5 lb/d of soy co-products, it could potentially increase soy co-product usage in beef diets by 13.5 million pounds per day. For soybean meal (assuming $300/ton cost), this would result in an additional $2.0 million dollars in soybean meal sales per day to the beef industry. Economic Analysis: In the proposal, we will calculate the economic cost of feeding soybean co-products containing isoflavones and amino acids in beef diets to reduce fescue toxicosis vs. no supplementation. It is expected that cattle supplemented with soy co-products, soy isoflavones, or soy amino acids will have reduced symptoms of fescue toxicosis and thus, provide a positive return on investment for beef producers.