Contents And Structures Of Condensed Tannins In Polygonum Viviparum At Different Growth Stages And Their Effects On The In Vitro Rumen Fermentation

Recent studies have shown that condensed tannins in plants can bind to proteins and affect rumen fermentation in ruminants,thereby exhibiting nutritional effects in increasing rumen protein and controlling methane emissions.The effects of condensed tannins on ruminant production depend not only on their content in plants,but also on their chemical structural characteristics.Polygonum viviparum is a dominant or subdominant species in the alpine meadow ecosystem,which is rich in nutrients and condensed tannins.At present,there are few studies in the world on the content and structure of the condensed tannins of P.viviparum and their effects on ruminant fermentation.Therefore,in this paper,P.viviparum was used as the research object to determine the content of condensed tannins in different growth periods and identify their structures,and to explore the effects of condensed tannins of P.viviparum.The content,structural characteristics of condensed tannins and their effects on ruminant nutrition provide a theoretical basis for the artificial cultivation of P.viviparum in the future,and provide useful information for livestock production.The main results of the study are as follows:(1)The condensed tannin content of P.viviparum was 63.60-141.62 g/kg DM,and the condensed tannin contents in different organs were significantly different(P<0.05).With the advancement of the growth period,the content of condensed tannins in P.viviparum showed a trend of increasing first and then decreasing.The average degree of polymerization of condensed tannin is 10-17 and the average molecular weight is 4154-7002.The structural monomer is mainly procyanidin(>80%);the terminal unit is mainly composed of catechin and epigallocatechin gallate composition;the extender unit is mainly composed of epicatechin and epicatechin gallate.(2)Condensed tannins of P.viviparum significantly reduced the gas production in the rumen in vitro fermentation,reduced the methane production by 5%-34%,the ammonia nitrogen content in the in vitro fermentation broth by 33%-40% and the total volatile fatty acid production by 10%-23%,and inhibited microbial protein synthesis.(3)Compared with the individual fermentation of Medicago sativa,the content of ammonia nitrogen in the rumen in vitro fermentation was significantly reduced when the leaves of P.viviparum were fermented with M.sativa at a percentage of20%,while the gas production,p H,dry matter degradation rate and total volatile fatty acid content were maintained.The rumen in vitro fermentation showed higher gas production rate,ammonia nitrogen content and microbial protein content when the bulbil of P.viviparum were fermented with M.sativa at a percentage of80%-100%.