Effect Of Different Molecular Weight Of Tannins From Alpine Plants On In Vitro Methane Production In Yaks

This paper could be divided into three parts. In the first part, five kinds of alpine plants from wushaoling was collected in8-10months, and the tannic and condensed tannin content were determined by Folin-Ciocalteu method and butanol hydrochloric acid method, samples of the highest condensed tannin content were selected. In the second part of the experiment, the purification and separation of CTs was conducted by using exclusion chromatography, purified CTs was divided into five fractions, and the molecular weight size of of the plant CTs was determined by gel permeation chromatography. For the last part, the fraction of different molecular weight CTs of each plant was used in in vitro rumen fermentation experiments. Gas production, pH, ammonia nitrogen content, DM degradability and neutral detergent fiber were determined to observe the changes and the impacts of the different molecular weight size CTs on rumen fermentation parameters and methane gas. It could be used to infer that the function of rumen fermentation in the reaction process and explored the mechanism of CTs involved in rumen environment regulation. Results were as follows:1、Alpine plants on cold area as Potentilla fruticosa, Polygonum viviparum, Kobresia tibetica Maximowicz, Salicaceae and Spiraea alpina, were rich in tannins and condensed tannins in August, September, October. Tannin content was higher in content with the month decrease, and content was significant difference between each month (P<0.05). Condensed tannins in Kobresia tibetica Maximowicz of September (4.79%DM) was highest, the lowest was Spiraea alpina in October with1.18%of DM. According to the plant total tannins and condensed tannin content sifted5kinds of sample in August Potentilla fruticosa, Polygonum viviparum, Kobresia tibetica Maximowicz, Salicaceae and Spiraea alpina into the next phase of experiment.2、The number average molecular weight between extraction purification condensed tannins from different plants were significant difference(P<0.05). Among five fraction condensed tannin extracted and purified of Potentilla fruticosa, the largest number average molecular weight was1926.5Da. Weight-average molecular weight was4081.6Da, higher than the other four kinds of plants. Sequence from big to small for molecular weight were Potentilla fruticosa> Kobresia tibetica Maximowicz> Polygonum viviparum> Salicaceae> Spiraea alpina. Minimum number average molecular weight of condensed tannins purification of Spiraea alpina was1390.9Da, Weight-average molecular weight was2284.3Da.3、The molecular weight sizes in different fraction of CTs isolated from the same plant were significant difference (P<0.05). Except V fraction of CTs from Potentilla fruticosa was more than4000Da. Relative molecular mass of each purified CTs fraction isolated different sample was between500Da and4000Da.4、The effect of CTs between different plants on gas production and the production of methane were significant difference (P<0.05). Inhibitory effect of Potentilla fruticosa, Polygonum viviparum and Kobresia tibetica Maximowicz on gas production and produce methane were more obvious than others. Potentilla fruticosa produced the largest inhibition on methane production, followed by Polygonum viviparum. Spiraea alpina stayed minimum inhibitory effect on methane inhibition. Effect of adding different molecular weight of CTs on in vitro rumen fermentation liquid pH, dry matter degradation rate was not significant (P>0.05). Rumen fermented liquid gas production, ammonia nitrogen content and neutral detergent fiber in vitro degradation rate by adding different molecular weight of CTs had significant inhibitory effect (P<0.05). Between different components of the CTs effect on gas production and the production of methane from significant difference (P<0.05). Molecular weight was significantly negative correlation with gas production, methane production, ammonia nitrogen content and in vitro dry matter degradation rate, the correlation coefficient r2were0.75,0.64,0.77,0.81. V fraction of CTs from Potentilla fruticosa whose CTs molecular weight was4331.9Da, inhibited79.8%methane generation.