Effects Of Lactic Acid Bacteria And Molasses On Nutrient Composition,Fermentation Quality And Bacterial Flora Of Alfalfa Silage

Due to the lack of water-soluble carbohydrates(WSC)necessary for microbial proliferation during fermentation,alfalfa is not suitable for silage alone because of its low dryness and strong buffering capacity.One of the most important issues in silage production is to reduce pH as quickly as possible.Lactic acid bacteria(LAB)and water-soluble carbohydrates are key factors for high silage quality during ensilage.Epiphytic lactic acid bacteria is insufficient on fresh herbage,so rapid and sufficient pH decline may not be achieved.Molasses(M)was used as a fermentation promoter to provide fermentable sugar for lactic acid bacteria growth,thus increasing the rate of acidification of silage,reducing pH value,and improving the quality of alfalfa silage.In this experiment,the effects of lactic acid bacteria and molasses as additives on the chemical composition content,fermentation quality,number of bacteria and bacterial flora of alfalfa silage after 14 and 56 days were studied by using small-scale fermentation method and alfalfa as raw materials,so as to provide theoretical basis for the production of high-quality silage.Alfalfa silage was put into laboratory polyethylene plastic vacuum bags for 14d and 56 d,and divided into 4 treatment groups with 3 replicates in each group.Fresh alfalfa was silage without any additives(CK group),lactic acid bacteria(L group),5% molasses(M group)and lactic acid bacteria+5% molasses(LM group).The chemical composition,fermentation quality and bacterial quantity of alfalfa silage were determined,and the bacterial community of alfalfa silage was analyzed by 16 rRNA sequencing.Through the addition of additives,crude protein(CP)and dry matter(DM)were preserved,water-soluble carbohydrates was fully utilized and promoted the fermentation of alfalfa silage,and pH decreased from 7.02 to 4.37-4.09.After silage,lactobacillus belonged to dominant bacteria in all treatments,so that the adverse microorganisms were inhibited.In summary,lactic acid bacteria and molasses are used as fermentation substrates for alfalfa silage fermentation.Soluble sugar is the basis of alfalfa silage fermentation.Molasses contains a small amount of amino acids,proteins and minerals,and also provides additional nutrients for lactic acid bacteria fermentation,providing a substrate for rapid accumulation of lactic acid(LA)and reducing pH value.In addition,the fermentation quality and bacterial community of alfalfa silage were improved,and the ideal pH value(less than 4.5)was obtained in each additive treatment group after 56 days,which is the best additive level for long-term preservation application.