Using polyethylene glycol to enhance the intake of sericea lespedeza by cattl

Sericea lespedeza (Lespedeza cuneata a.k.a. 'sericea') is a forage legume introduced into the U.S. from Asia in 1896. Older varieties contain high concentrations of condensed tannins that have anti-nutritional characteristics which deter foraging by livestock. These varieties have become invasive in pasture and rangeland in the tallgrass prairie region of the Great Plains.;Polyethylene glycol (PEG) is a polymer with known tannin-binding properties. We hypothesized that supplementing steers with PEG would mitigate the anti-nutritional impacts of condensed tannins in the sericea and thereby increase sericea intake.;In a pen study, steers supplemented with PEG consumed more sericea than Control steers in intake trials when sericea and prairie hay were fed in separate meals. Supplementation with PEG elicited an even stronger response in preference tests when the two groups of steers had a simultaneous offer of sericea and prairie hay.;In grazing trials over 2 years, steers supplemented with PEG consumed more sericea than steers who did not receive PEG. However, the response was less pronounced than in the pen study. Availability of high-quality alternatives in pastures might have attenuated the effects of PEG supplementation of sericea intake. In both years of the grazing study, most of the sericea consumption by steers in both treatments occurred after August 20. Analysis of the relationship between sericea cover and grass cover in the pastures indicated that the negative relationship between sericea and grass cover was strongest in plots with greater than 50% sericea cover.;Variation in sericea consumption among steers in the same treatment during the pen study showed larger within-group differences in the preference tests than in the intake trials. There was only modest variation in the amount of sericea consumed by individual steers within the same pasture during the 2 years of pasture trials.;In addition to supplementing PEG to cattle, factors such as the time of grazing, availability of alternatives, and selection of animals were important in maximizing sericea intake by cattle grazing tallgrass prairie rangelands infested with sericea.