Endophyte-infected (E+) tall fescue is an important forage for livestock operations, but cattle consuming this forage can develop fescue toxicosis with symptoms including depressed prolactin, vasoconstriction, and decreased growth rates that can persist as long as 5 wk after grazing. Isoflavones found in forage legumes, such as red clover, can alleviate fescue toxicosis symptoms. This study was conducted to determine if isoflavone supplementation via red clover hay, daily or every other day (QOD), would improve growth performance of beef steers while grazing E+ tall fescue pastures and reduce postgraze recovery time. Steers supplemented with isoflavones via red clover hay daily or QOD had greater weight gain over the grazing period (2018:62 d; 2019:65 d) and had shorter postgraze recovery from prolactin depression and vasoconstriction, when compared with steers supplemented with a common isoflavone-free protein supplement, dried distillers’ grains with solubles. The results of this study suggest that isoflavone supplementation could be an effective management strategy to alleviate fescue toxicosis-related health and performance losses in beef steers, both during and after grazing. More research is needed to determine how isoflavone supplementation while grazing E+ tall fescue could benefit the health and performance of cattle when transitioning to the finishing phase of production.

Read the full article in the Journal of Animal Science.