Response of rumen microbial ecosystem to diets integrated with chestnut or quebracho tannins in dairy ewes

The aim of this study was to evaluate the response of ewe rumen microbial communities to diets integrated with chestnut (CHT) or quebracho (QUE) tannins, to increase the quality of dairy products and to reduce methane emissions in the atmosphere. Three fistulated ewes fed 3 diets based on chopped grass hay ad libitum administered and bentonite (CON) or CHT or QUE were used in a 3 X 3 Latin square experimental design. At the end of each experimental period, rumen liquor was analysed for fatty acid profiles by gas chromatography, and microbial diversity using a DGGE approach. CH4 emission was also predicted on the basis of the molar stoichiometric relations between rumen volatile fatty acid and CH4. The microbial profile was affected by the presence of tannins. The rumen liquor bacterial communities of QUE and CHT samples were correlated to C18:1 trans-11, C18:2 cis-9-trans 11 and C18:2 trans-11 cis-15. Moreover, the bacterial communities as affected by CHT resulted mainly correlated to C4:0, C3:0 and with potential CH4 emission. In contrast, the bacterial communities as affected by CON resulted mainly correlated to C18:2 cis-9 cis-12 and C18:0 production.