Jin, L., Wang, Y., Iwaasa, A. D., Xu, Z., Schellenberg, M. P., Zhang, Y. G. and McAllister, T. A. 2013. Short Communication: Effect of condensed tannin on in vitro ruminal fermentation of purple prairie clover (Dalea purpureaVent)-cool- season grass mixture. Can. J. Anim. Sci. 93: 155–158. Four purple prairie clover [Dalea purpurea Vent (PPC)]-/grass mixtures containing 7.3, 14.0, 29.3 and 42.1 g kg^-1 dry matter (DM) of condensed tannin (CT) were incubated with rumen fluid. As the CT increased, in vitro true dry matter disappearance (IVTDMD), production of volatile fatty acids (VFA) and microbial protein synthesis were linearly increased (P<0.05) at 12 h, and IVTDMD and VFA were quadratically increased (P<0.01) at 48-h incubation. Molar proportion of acetate was linearly increased (P<0.01) but propionate and butyrate were decreased (P<0.05) at both 12 and 48-h incubation. Incorporation of PPC into cool-season grass pasture up to CT content of 42 g kg^-1 DM improved ruminal fermentability and microbial protein synthesis in mixed forages.