Effects Of Sweet Sorghum Silage On Rumen Degradation?Aerobic Stability And Ruman Flora

Sweet sorghum is a kind of crop with high development potential,high sugar content,drought resistance and barren tolerance.There have some reports about effects of sweet sorghum silage on animal performance.However,effects of different sweet sorghum silages on aerobic stability,rumen degradation characteristics,and rumen microbes were rarely reported up to now.Therefore,three kinds of silages made of high sugar sweet sorghum(HSS),low sugar sweet sorghum(LSS),and maize(MZS)were used as experimental materials to invesgate their aerobic stability,rumen degradation,and rumen microbes by nylon bag degradation test,DGGE,and high-throughput sequencing technology,as well as used to analyze the changes of dry matter(DM),water soluble carbohydrate(WSC),pH value,temperature and microbial populations during aerobic exposure on 0,5,10,15,20 and 25 days.The main results are as follows:(1)The LSS had the best aerobic stability with the least number of yeast,fungi and aerobic bacteria,while HSS had the lowest aerobic stability with the highest number of yeast,fungi and aerobic bacteria under aerobic environment,and the aerobic stability and aerobic bacteria number of MZS fall in between HSS and LSS.(2)The study of rumen degradation experiment showed that the degradation of dry matter(DM),neutral detergent fiber(NDF)in HSS were significantly higher than those in MZS and LSS during the early stages of fermentation in rumen(P<0.05),while the degradation of DM and NDF reached almost the same level HSS and MZS at 24 h of fermentation(P>0.05).The degradation of crude protein(CP)in HSS was significantly higher than that in MZS and LSS at 24 and 48 h of fermentation(P<0.05).(3)Compared with LSS,feeding HSS and MZS increase the number and kinds of rumen microbes,and similarity of rumen microbes caused by feeding HSS and MZS was 80%,while that caused by LSS,HSS and MZS was only 60%.(4)Cows fed HSS and MZS had similar rumen bacteria community structures,and there were different from those fed LSS in rumen bacteria community.The dominant bacteria with LSS was Firmicutes,while the dominant bacteria with MZS and HSS were Bacteroidetes and Proteobacteria in term of phylum.According to family and genus,Prevotella is dominant bacteria in rumen with MZS and MZS,and Lachnospiraceae was main bacteria in rumen with LSS.Fibrobacter succinogenes in rumen with HSS accounted for 1.5% of total rumen bacteria,however,it was not detected in rumen with LSS.Ruminococcus flavefaciens in rumen with HSS amounted to 1.4% of total rumen bacteria,and it accounted about 0.25% of total rumen bacteria with LSS and MZS.Ruminococcus albus was not detected in rumen with any of the silage.This study demonstrates that HSS and MZS had high similarity in rumen degradation,rumen microbe diversity and dominant bacteria.HSS increased the number of R.flavefaciens and F.succinogenes,which suggests that the high degradation of HSS can be obtained by regulating the growth of rumen microorganism.At the same time,some measures should be taken to increase aerobic stability of HSS because it is prone to secondary fermentation under aerobic conditions.