Effects of fermentation time on conventional nutrients,fermentation index,rumen in vitro fermentation gas production,and microbiota structure of alfalfa silage

HU Yuyang; LUO Chenglong; WANG Zhonghan; WANG Qianqian; ZHAO Liwei; WU Zhenyue; ZHUANG Qiaoyue; WANG Wei

doi:10.13557/j.cnki.issn1002-2813.2025.11.020

Abstract：The experiment aims to explore the effects of fermentation time on the conventional nutrients,fermentation index,rumen in vitro fermentation gas production,and microbial community structure of alfalfa silage.Alfalfa hay was fermented for 0,60,90 and 120 days respectively,and the contents of conventional nutrients,volatile fatty acids(VFA),cumulative gas production of fermentation substrates,and rumen flora structure were determined.The results showed that crude fat significantly increased with fermentation time(P＜0.05).Both neutral detergent fiber and crude ash content showed a significant decreasing trend with fermentation time(P＜0.05).The cumulative gas production after 48 hours of in vitro fermentation at 90 and 120 days was significantly lower than that at 60 days(P＜0.05).The theoretical maximum gas production of the fermentation substrate at this gas production rate decreased with the increase of fermentation time,and was significantly lower at 90 and 120 days than at 60 days(P＜0.05).The curve inflection point parameter of the substrate fermentation gas production process at 120 days was significantly higher than that at 60 days(P＜0.05).The time required to reach the maximum gas production rate and substrate degradation rate of alfalfa silage after 120 days of fermentation were significantly higher than those after 60 days(P＜0.05).The maximum gas production rate and substrate degradation rate at 60 days of fermentation were significantly higher than those at other times(P＜0.05).Except for acetic acid,the production of various VFA and total VFA significantly decreased at 60～90 days of fermentation(P＜0.05),and significantly increased at 90～120 days(P＜0.05).At the phylum level,the relative abundance of Actinobacteria in rumen fluid of alfalfa silage fermented for 90 days after in vitro fermentation was significantly higher than that at 60 and 120 days(P＜0.05).At the genus level,the relative abundance of Actinobacillus succinogenes gradually decreases with increasing fermentation time.The research shows that alfalfa silage fermented for 120 days has the best conventional nutrient content and feeding quality.