Study On The Fermentation Quality Of King Grass Silage Cut At Different Time

In this study,the fermentation quality of king grass silage harvested at different growth days and daytimes was studied,and excellent lactic acid bacterial strains were screened from fresh king grass and king grass silage,then the effects of lactic acid bacterial strains on the fermentation quality of king grass silage were further explored,which can provide a theoretical basis for king grass silage making in tropical areas.This research consists mainly of three experiments.Experiment 1.Fermentation quality and microbial composition of king grass silage cut at different growth days and daytimesAfter 90,110 and 130 days of growth,king grass was harvested at 8:00,12:00,and 18:00,respectively,then made into silage.The silage bags were opened after 1,3,7,14,30,and 60 days of ensiling for fermentation quality analysis.The results showed that in the three cutting times of 8:00,12:00,and 18:00,king grass with 130 days of age had the lowest crude protein(P<0.05),and the highest dry matter content(P<0.05).The readings of yeast,mold and coliform bacteria of the 110-day group were lower than those of the king grass with 90 and 130 days of growth.The pH of110-day silage decreased rapidly during ensiling with higher lactic acid content than that of 90 and 130 days.The pH value of 110-day silage was the lowest after 60 days of ensiling with less degradation of crude protein,and the ammonia nitrogen content was the lowest.The butyric acid content of king grass silage was high in all groups after ensiling.The microbial alpha diversity decreased with prolonged growth days.The relative abundance of lactic acid bacteria at the genus level of silage with 110 days of growth was higher than that of the 90 and 130 days.Proteobacteria dominated in phylum level in 60-day silage.The dominant genera of 110-day king grass silage at three harvesting times were Lactobacillus and Lactococcus,and the level of Clostridium was shown to be low.Clostridium remained high in 90-day and 130-day silage cuttings at 12:00 and 18:00.In conclusion,the silage fermentation quality of110-day grass is shown to be better than that of 90 and 130 days.Experiment 2.Screening of lactic acid bacteria from fresh king grass and king grass silageLactic acid bacterial strains with strong growth ability and high acid production efficiency were isolated and screened from fresh and silage samples,and the screened lactic acid bacterial strains were identified by 16 s rRNA.The results showed that 4strains of lactic acid bacteria were isolated from fresh king grass and silage samples,including 2 strains of Pediococcus pentosaceus,1 strain of Enterococcus faecalis and1 strain of Pediococcus acidilactici.Both two strains of Pediococcus pentosaceus could grow at pH 3.5–8.0,while Enterococcus faecalis and Pediococcus acidilactici could grow in the pH range of 4.0–8.0.Enterococcus faecalis could grow at 50 ℃,and the acid production performance and ability of growth presented in Pediococcus lactis were weak.Experiment 3.Effects of lactic acid bacteria on the quality and microbial communities of king grass silageLactobacillus plantarum,Pediococcus pentosaceus,Enterococcus faecalis,Lactobacillus plantarum plus Enterococcus faecalis,Lactobacillus plantarum plus Pediococcus pentosaceus,and Lactobacillus buchneri were use as additive in king grass silage.The results showed that BA-type fermentation easily occurred in king grass silage process of high moisture content.The dominant phylum changed from Proteobacteria and Cyanobacteria in fresh material to Firmicutes in silage after ensiling.Inoculating Lactobacillus buchneri significantly increased the content of acetic acid and reduced the number of yeasts,while applied lactic acid bacteria can accelerate the inhibition of mold reproduction in silage.The application of Lactobacillus plantarum,Pediococcus pentosaceus,Enterococcus faecalis and Lactobacillus buchneri had a synergistic effect on the growth of Lactobacillus plantarum.