Sahoo et al., 2010. Livest. Res. Rural Dev., 22 (7): 119

The present studies were undertaken to evaluate the effect of hydrolysable (HT) and condensed tannins (CT) (at the rate of 1 mg per 26 mg crude protein) on ruminal degradability of protein in locally available tree forages using in vitro gas and ammonia (NH3) production method.   The NH3-N content after 24 h incubation decreased with added starch. Gas production (24h) decreased with added HT and CT for all forages except in Albizia stipulata. In vitro ruminal disappearance of nitrogen (IVRDN) calculated by linear regression in untreated forages was observed to be highest (63.2 %) for Grewia optiva and lowest 0 %) for Quercus incana. With added tannins, IVRDN values varied from 4.8% (Acacia lakoocha) to 33.2% (Grewia optiva). Addition of HT resulted in increase in IVRDN values of Acacia catechu, Albizia stipulata, Bauhinia variegata, Dendrocalamus hamiltonii, Ficus roxburghii, Leucaena leucocephala, Morus alba and Quercus incana. Comparatively, addition of HT was more effective in increasing IVRDN than CT. However, the IVRDN values when calculated with blank for NH3-N without added HT decreased with addition of HT in all the forage samples. Tree forages with added CT exhibited an inconsistent response for IVRDN values. The values were maximum (34.4 %) for Morus alba and minimum (6.5 %) for Quercus incana. The correlation between IVRDN and fiber bound tannins was non-significant but positive and significant (P<0.02) between IVRDN and CP content of the forages. A higher slope in the regression equations observed in presence of tannins indicated higher uptake of ammonia by ruminal microbes and possibly to increased microbial protein synthesis.