Defoliation of panicled tick-clover, tweedy`s tick-clover, and tall bush-clover: ii. Herbage nutritive value and condensed tannin concentrations
Few native herbaceous perennial warm-season legumes are available for cultivation in the southern United States. These would be useful for pastures, biomass production, wildlife plantings, rangeland reseeding, or native prairie restoration. Three native perennial legumes were selected from an initial screening of north Texas germplasm for potential domestication based on successful establishment, ease of seed harvest, and herbage production. Response to herbage removal was evaluated by measuring forage nutritive value when clipped at 10-, 20- and 40-cm height (whenever regrowth exceeded 20 cm above cutting height) over three seasons in 2- by 2-m plots with 0.5 m between plants. Tweedy's tick-clover (Desmodium tweedyi Britton) became reproductive in June so herbage acid detergent fiber (ADF) (338–373 g kg–1) was greater (P < 0.05) than tall bush-cover (Lespedeza stuevei Nutt.) and panicled tick-clover [D. paniculatum (L.) DC.] that both flowered primarily in September. Herbage N concentrations were uniformly (P > 0.05) high (31.7 g kg–1) the first year and unaffected by harvest height all 3 yr; by the third year, however, tall bush-cover had the lowest (P < 0.05) N concentration (22.6 g kg–1) and in vitro dry matter disappearance (IVDMD; 651 g kg–1). Condensed tannin (CT) concentrations exceeded 120 g kg–1 for both the panicled tick-clover and the tall bush-clover although fraction distribution varied among entries. These three native North American legumes show potential as nutritious forage components to natural and cultivated systems.