Phosphorus and other nutrient disappearance from plants containing condensed tannins using the mobile nylon bag technique

A study was designed to evaluate nutrient disappearance from three Texas browse species containing condensed tannins (CT; Acacia angustissima var. hirta, Desmodium paniculatum, Smilax bona-nox, and Medicago sativa as control) using the mobile nylon bag technique. Ruminally or duodenally cannulated steers were fed a basal diet of Sorghum bicolor × S. sudanense hay. The proportion of nutrient that disappeared during rumen, pepsin/HCl, or intestinal incubation differed among plant species and nutrient evaluated (P<0.05) and did not appear to be directly related to relative CT concentrations. Dry matter (DM), inorganic matter (IM), and organic matter (OM) disappearance was greater (P<0.05) during rumen incubation than at other stages for all plant species evaluated. Of the plants containing CT, A. angustissima demonstrated the greatest overall disappearance of DM, OM, P, and crude protein (CP). A greater proportion of A. angustissima and D. paniculatum CP and P disappearance occurred in the intestinal tract compared to S. bona-nox and M. sativa. The presence of CT appears to reduce total P disappearance and shift disappearance site from the rumen to the intestines in some plant species containing CT.