From the lab bench: Mixtures of grasses and legumes; a good or bad thing?

Authors: AIKEN, GLEN

Submitted to: Cow Country News
Publication Type: Popular Publication
Publication Acceptance Date: 8/22/2016
Publication Date: 9/1/2016
Citation: Aiken, G.E. 2016. From the lab bench: Mixtures of grasses and legumes; a good or bad thing?. Cow Country News. Pgs. 70-71.

Interpretive Summary: Toxic endophyte-infected tall fescue has been the predominant grass in Kentucky pastures, but other grasses are starting to encroach these grasses. Cattle performance is generally low in tall fescue because of ergot alkaloids produced by a fungal endophyte, but volunteer emergence of Kentucky bluegrass, orchardgrass, bromegrass into fescue pastures can enhance cattle productivity. This is because consumption of these other grasses by cattle can dilute ergot alkaloids in the diet and there higher nutritive values can further enhance diet quality. Further, by grazing a diverse mixture of grasses and legumes, the cattle are not grazing a single grass that could likely be limited in a nutrient(s). Grazing a mixture of grasses and legumes can allow a nutrient limitation of the predominant grass, such as tall fescue, to be overcome by consumption of other forages. This information will be helpful to livestock producers in Kentucky and other states in the upper south that are witnessing more species diversity in the tall fescue pastures.

Technical Abstract: A column was written to discuss the advantages of complex mixtures of grasses and legumes. Historically, Kentucky pastures have been primarily composed of toxic endophyte-infected tall fescue, but Kentucky bluegrass and other grasses are presently encroaching tall fescue pastures. These other grasses, orchardgrass, bromegrass (Smooth and Downy bromegrasses), and crabgrass, have greater potential than toxic endophyte tall fescue in promoting greater cattle production and welfare. We have witnessed gradual increases in weight gain of our steers on grazing trials with toxic endophyte-infected tall fescue as Kentucky bluegrass, orchardgrass and bromegrass have voluntarily emerged and are being grazed. These other cool-season perennial grasses can offer the same or higher nutritive value than fescue and, more important, do not contain toxic ergot alkaloids. Therefore, consumption of these grasses will dilute the toxic ergot alkaloids produced by the fungal endophyte and enhance diet quality.