Effect Of Different Lactic Acid Bacteria On Fermentation Characteristics And Bacteria Diversity Of Alfalfa Silage

The objective of this research was to evaluate the effects of LAB on fermentation characteristics, aerobic stability and microbial community of alfalfa silage when applied homo-fermentative Lactobacillus plantarum and hetero-fermentative Lactobacillus buchneri. There were four treatments: the control(0 additives)(CS), the Lactobacillus buchneri(5×106cfu/gFM additives)(HS), the Lactobacillus Plantarum(5×106cfu/gFM additives)(SS) and the Lactobacillus buchneri added in Lactobacillus Plantarum(2.5×106cfu/gFM, respectively, additives)(MS). The pH value, concentrations of DM, CP, NDF, ADF, VFAs, WSC, ammonia N and the microbiotas were detected on day 3, day 5, day 7, day 10, day 15, day 30, day 60 during ensiling. The results are shown as follows:(1) The addition of LAB could reduce pH value of ensilage effectively. The three silages treated with Lactobacillus plantarum or Lactobacillus buchneri were well preserved with lower pH values than the control did. The pH values of 60 day of ensilage were CS(4.04) > HS(4.00) > MS(3.69) > SS(3.88).(2) SS and HS had significantly highest contents of lactic acid and acetic acid compared to other groups, and CS had significantly higher contents of propionic acid and butyric acid concentrations than others(p<0.05).(3) Four treatment groups had no significant difference on NDF and ADF(p >0.05), WSC concentrations in CS was significantly lowest than that in other groups(p <0.05). The contents of DM, CP and NH3-N in HS was significantly different from that in others(p <0.05).In conclusion, MS showed better effects on reservation of WSC, DM and CP, and production of LA and ACE, while its NH3-N production was lower than the control group,which significantly improved fermentation characteristics of alfalfa silage.After 60 days of storage, the silages were subjected to an aerobic stability test. As a result: Control silages spoiled faster upon aerobic exposure than treated did, HS had 75.8% improved than control group, MS and HS had prolonged 144 h, 60 h than CS. The results indicated Lactobacillus buchneri alone or in combination with Lactobacillus plantarum improved aerobic stability.This study investigated the development of the microbial community during 60 days anaerobic digestion of alfalfa silage. For the characterization of the microbial dynamics, culture-independent high-throughput sequencing was applied.(1) Most of the sequences in all the samples were found to belong to the five most populated bacterial phyla including Firmicutes, Bacteroidetes, Actinobacteria, Proteobacteria and Fusobacteria, accounting for 98% for the virtual bacteria.(2) The addition of LAB improved abundance of Firmicutes in treated groups. An increase in relative abundance was observed for Fusobacteria, Bacteroidetes(Capnocytophaga, Capnocytophaga_granulosa) Proteobacteria(Veillonella_ sp._ oral_ clone_ VeillB9, Veillonella_ parvula) and Actinobacteria when LAB was applied.The study reveals the effects of dynamic variation of the microbial community on fermentation characteristics and nutrition, providing a theoretical basis for production practice.