Sericea lespedeza is an invasive weedy species in the tall grass prairie region. Over 700,000 acres in Kansas are infested sericea and widespread infestations are also reported in Northeast Oklahoma and Southwest Missouri. At high densities, it crowds out native plant species. The economics of controlling sericea with herbicides are debatable and herbicides also damage many species other than sericea. Cattle avoid eating sericea because it is high in tannins, compounds that bind to protein and cause food aversions in ruminants. In studies conducted in the Flint Hills of Kansas, Utah State University graduate student, Greg Mantz, research assistant professor, Juan Villalba, and professor, Fred Provenza, are investigating supplementing cattle with polyethylene glycol (PEG) to increase consumption of sericea thereby decreasing its spread. PEG binds to tannins and renders them inactive.

In stall trials, steers supplemented with PEG doubled consumption of the sericea compared with steers that did not receive PEG. Moreover, when steers supplemented with PEG were offered a choice between sericea and grass hay their preference for sericea was more than double of steers not receiving PEG.

In pasture trials, sericea comprised 16% of the grazing bites for the steers in the PEG-supplemented pastures and 7% of the grazing bites in the control pastures. In two years of pasture trials, the overwhelming majority of sericea use occurred after August 20. Although sericea tannin levels showed only a modest decrease in the late-season, previous research in North Carolina indicates qualitative changes in sericea tannin occur in late August which decreases the anti-nutritional effects of the tannin. It should be noted that sericea never comprised more than 12% of total plant cover in any pasture during the study.

In summary: 1) Due to declining anti-nutritional effects of sericea tannin in mid-August through September coupled with the decline in grass quality during that same time period cattle will selectively consume sericea from mid-August through September. 2) Adding PEG to a 20% crude protein supplement will further increase sericea consumption. By stocking sericea-infested tallgrass pastures heavily from mid-August through September and supplementing with a 20% crude protein supplement containing PEG, it may be possible to decrease the competitiveness of sericea lespedeza while providing animals a nutritious alternative to the low-quality fall grass.

Cope, W.A., Bell, T.A. and W.W.G. Smart Jr. 1971. Seasonal Changes in an enzyme inhibitor and tannin content in sericea lespedeza. Crop Science. 11: 893-895.