Current research in red clover isoflavones as functional feed in beef cattle production

Authors: Harlow, Brittany; Flythe, Michael

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 9/13/2019
Publication Date: 9/13/2019
Citation: Harlow, B.E., Flythe, M.D. 2019. Current research in red clover isoflavones as functional feed in beef cattle production. Meeting Proceedings. 1:20.

Interpretive Summary:

Technical Abstract: The pasture legume red clover is rich in protein and is often included in grazing systems to improve pasture health and quality; consequently, improving animal performance. Clovers, like many other legumes, also make isoflavones that have been shown to be vasodilators and have selective antimicrobial action. This talk will cover recent research exploring red clover and it’s isoflavones as “functional feeds” in cattle production to improve health and performance. In our laboratory group, pure cultures of HAB are often used to screen plant compounds for antimicrobial activity. If antimicrobial activity is observed, the compound is then subjected to a series of tests to determine if it harms beneficial microorganisms from the rumen and if it is safe for animal use. Red clover isoflavones, including purified biochanin A, were found to be inhibitory to HAB while not harming beneficial bacteria like those that utilize fiber. Furthermore, the effective dose was within the range that we see naturally in red clover varieties. The initial grazing trial was conducted with growing steers grazing cool season grass pastures that contained endophyte-free tall fescue. Steers were assigned to one of three treatments: 1) pasture-only control, 2) protein supplemented control (DDG to meet maximum growth requirements), or 3) protein supplemented + purified biochanin A (dosed to represent a 30% pasture clover stand). Protein supplementation alone improved average daily gains (ADG) 13% relative to the pasture-only control, but the addition of purified biochanin A boosted this benefit to a 29% increase in ADG. The biochanin A supplementation level in the initial grazing trial was designed to represent a 30% red clover diet. Although there are producers who may already have available or could establish a 20 to 40% red clover pasture, there are many producers who do not have this ability. To evaluate if lower levels of red clover supplementation could provide performance benefits in growing steers, grazing trials were conducted supplementing high and low levels of red clover hay. Steers were assigned to one of four treatments: 1) pasture-only control, 2) protein supplemented control, 3) protein supplemented + low level of red clover hay (15% red clover hay diet), or 4) protein supplemented + high level of red clover hay (30% red clover hay diet). As seen previously, both protein supplementation alone and a high level of red clover hay improved ADG in comparison to pasture-only controls. Interestingly, the low red clover hay treatment was most effective at improving ADG (+~18% ADG relative to DDG and high red clover hay treatments). These results indicate that there is an optimum level of red clover or isoflavone supplementation for improving performance in growing cattle. Future research is needed to look at lower levels of supplementation.