Abstract:
EFFECT OF TANNIN ON DIGESTION OF LOTUS CORNICULATUS BY SHEEP G.C. WAGHORN Condensed tannins (CT) bind to proteins forming a stable complex in the pH range 3.5-7.0, but dissociate at pH below 3.5 (Jones & Mangan, 1977) r therefore proteins in plants containing tannin should be protected from microbial degradation in the rumen, and in theory be released in the abomasum for absorption in the small intestine. Sheep fed legumes containing low (< 4% of DM) concentrations of CT have a higher retention of nitrogen (N) than comparable tannin free forages (Egan & Ulyatt, 1980). The nutritional consequences of CT were evaluated in Lotus corniculatus L. (2.2% CT) by comparing four control ('tannmsheep with f&r sheep receiving an intraruminal infusion of 50 g/day polyethelene glycol (PEG) to preferentially bind CT, and free plant proteins ('no tannin' group). Sheep were fed about 1400 g DM/day in hourly increments. The apparent digestion of energy, neutral detergent fibre (NDF), nitrogen (N), and amino acids (AA) were determined pre abomasum (rumen) and in the small and large intestine, by using dual markers in conjunction with abomasal sampling, and terminal ileal sampling at slaughter. Nutritional EGA-N, A . R . and ULYATT , M.J. JONES, W.T. and MANGAN, J.L. (1980). J. agric. Sci., Camb. 94: 47. (1977). J. Sci. Fd Agric. 28~~126. -~~~~ Applied Biochemistry Division, DSIR, Palmerston North, New Zealand. ___