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Degradation of condensed tannins by rumen microbes exposed to quebracho tannins (QT) in rumen simulation technique (RUSITEC) and effects of QT on fermentative processes in the RUSITEC
Author(s) -
Makkar Harinder P S,
Becker Klaus,
Abel Hj,
Szegletti Csaba
Publication year - 1995
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740690414
Subject(s) - rumen , proanthocyanidin , tannin , condensed tannin , dry matter , food science , propionate , zoology , chemistry , biology , fermentation , botany , polyphenol , biochemistry , antioxidant
In an earlier study it was observed that the rumen microbes from cattle which had never consumed tannin‐containing diets do not have enzymes for degrading condensed tannins. In this study, rumen microbes were exposed to small amounts of quebracho tannins for 8 days using a rumen simulation technique (RUSITEC). The levels maintained in the RUSITEC were 0.1, 0.2 and 0.4 mg of the spray‐dried quebracho powder (SDQT) per ml of the medium. After 8 days of tannin exposure, the liquor containing ‘exposed/adapted’ microbes from RUSITEC was incubated for 40 h without and with purified tannins of quebracho and Dichostachys cinerea leaves in in vitro gas method. There was no degradation of condensed tannins. The enzymes for degradation of condensed tannins were not induced in rumen microbes by exposure to different concentrations of tannins for 8 days in the RUSITEC. In the RUSITEC, SDQT significantly reduced the number of total protozoa, entodiniomorphs and holotrichs; effect was higher on holotrichs. There was no significant change in the levels of short chain fatty acid but the molar proportion of propionate was significantly higher and of butyrate significantly lower at 0.4 mg SDQT ml −1 . Significantly lower levels of ammonia in the medium was also observed on injection of tannins. Microbial mass production, calculated using 15 N incorporation, was similar at 0.1 and 0.2 mg SDQT ml −1 but significantly lower (13%) at 0.4 mg SDQT ml −1 . The dry matter digestibility of the feed (80% hay and 20% barley) was not significantly affected by SDQT.