Study On Silage Quality Regulation Of Sugarcane Tops With Different Water-soluble Carbohydrate Content

Guangxi is rich in sugarcane resources,and sugarcane with different sugars has different water-soluble carbohydrates（WSC）in the sugarcane tops.WSC is an important fermentation substrate in the silage process.The purpose of this experiment was to explore the effects of different WSC contents on the fermentation quality of sugarcane tops with different ensiling time,and the effects of citric acid or sodium diacetate on its silage quality and microbial diversity,those study could provide a scientific basis for preparing high-quality sugarcane tops silage in Guangxi Province.The research contents and main results are as follows:（1）Effect of ensiling time on silage quality of sugarcane tops with different WSC contentsSugarcane tops with low WSC,medium WSC,and high WSC content was used as the materials to analyze its silage quality over a period of 125,155,and185 days.The results showed that the nutritional components of silage decreased with the increase of ensiling time.The dry matter loss rate,ethanol content,and p H of the silage at 125^thday were significantly lower（P<0.05）and lactic acid content was significantly higher（P<0.05）than those at 155^thand 185^thdays.The ammonia nitrogen and dry matter loss rate of the low WSC sugarcane tops significantly increased（P<0.05）and was highest after ensiling.During aerobic exposure,the number of yeasts and molds in high WSC sugarcane tops silage significantly increased（P<0.05）.（2）Effects of citric acid or sodium diacetate on the quality of sugarcane tops silage with different WSC contentsExperiment 1:Effect of citric acid on sugarcane tops silage quality with different WSC contentsSugarcane tops with low WSC and high WSC content was used as silage material,and 0%,0.1%,0.5%,1%citric acid under fresh weight were added to explore the change of silage quality.The results showed that the addition of citric acid decreased the rate of dry matter loss after silage of both sugarcane tops.After 125 days of silage,the contents of ammonia nitrogen,ethanol,butyric acid,Enterobacter and p H of 1%citric acid group were significantly lower than those of other groups（P<0.05）.1%citric acid significantly decreased the contents of ammonia nitrogen and the number Mold and Enterobacter during aerobic exposure of the two sugarcane tops（P<0.05）.Experiment 2:Effect of sodium diacetate on sugarcane tops silage quality with different WSC contentsSugarcane tops with low WSC and high WSC content was used as silage material,and 0%,0.1%,0.5%,1%sodium diacetate under fresh weight were added to explore the change of silage quality.The results showed that after 125days of silage,1%sodium diacetate significantly increased the ammonia and nitrogen content and the dry material loss rate（P<0.05）.1%sodium diacetate significantly reduced the ammonia nitrogen and mold content（P<0.05）during the aerobic exposure of both sugarcane topss and reduced the fermentation loss.（3）Effects of citric acid and sodium diacetate on microbial diversity of sugarcane tops with different WSC contents after aerobic exposureTo explore the effects of adding 1%citric acid and 1%sodium diacetate on the diversity of bacteria and fungi after aerobic exposure of sugarcane tops silage with low WSC and high WSC content after aerobic exposure.The results showed that during aerobic exposure,the relative abundances of Bacteroides,Pseudomonas and Bacillus in low WSC sugarcane were significantly higher than those in high WSC sugarcane（P<0.05）,Lactobacillus,Sporolactobacillus,Pantoea relative abundance was significantly lower than that of high WSC sugarcane tops（P<0.05）.The addition of 1%citric acid significantly decreased the relative abundance of Clostridium sensu stricto-12,Meyerozyma at 0 days,4days,8 days,16 days of aerobic exposure（P<0.05）,and significantly decreased the relative abundance of Bradyrhizobium and Pseudomonas at 8 days,16 days of aerobic exposure（P<0.05）.The addition of 1%sodium diacetate significantly increased the relative abundance of Firmicutes and Lactobacillus（P<0.05）and significantly decreased the relative abundance of Proteobacteria,Zygomycota,Clostridium-sensu-stricto-12 and Pantoea during aerobic exposure of high WSC sugarcane tops（P<0.05）.Spearman correlation analysis showed that Lactobacillus was significantly positively correlated with acetic acid and ethanol（P<0.05）,and significantly negatively correlated with ammonia nitrogen and butyric acid（P<0.05）;Clostridium-sensu-stricto-12 was significantly positively correlated with ethanol,Ammonia nitrogen,lactic acid,propionic acid and butyric acid（P<0.05）,and significantly negatively correlated with p H（P<0.05）;Pantoea and Enterobacter were significantly positively correlated with ethanol,ammonia nitrogen and butyric acid,and significantly negatively correlated with p H（P<0.05）;Monascus was significantly positively correlated with ethanol（P<0.05）,and significantly negatively correlated with p H（P<0.05）;Saccharomyces was significantly negatively correlated with lactic acid（P<0.05）,and significantly positively correlated with p H（P<0.05）;Monascus was significantly positively correlated with Bacillus,Bradyrhizobium,Aneurinibacillus,Paenibacillus and Pseudomonas（P<0.05）.In conclusion,there are obvious differences in the silage quality of sugarcane tops with different WSC contents.Under this test condition,the silage quality is the best for 125 days.After 125 days of silage,with citric acid or sodium diacetate decreased dry matter loss and fermentation losses in sugarcane tops with low and high WSC content.Low WSC sugarcane tops 1%citric acid and high WSC sugarcane tops 1%sodium diacetate inhibited the growth of undesirable bacteria and fungi during aerobic exposure,and the effect was better.