Dynamics of the Fermentation Products, Residual Non-structural Carbohydrates, and Bacterial Communities of Wilted and Non-wilted Alfalfa Silage With and Without Lactobacillus plantarum Inoculation

Abstract

The aim of this study was to investigate effects of wilting and Lactobacillus plantarum inoculation on the dynamics of the fermentation products, residual non-structural carbohydrates, and bacterial communities in alfalfa silage. Fresh and wilted alfalfa were ensiled with and without L. plantarum for 10, 30, 60, and 90 days. A high-throughput sequencing method for absolute quantification of 16S rRNA was adopted to determine the bacterial community composition at different ensiling periods. For the wilted silage, the bacterial community, pH value, and ammonia nitrogen concentration remained stable in the silage at 30 days. L. plantarum inoculation accelerated lactic acid fermentation and altered the predominant genus in the wilted silage as compared with the non-inoculated group. For the non-wilted group, fast consumption of water-soluble carbohydrates (WSCs) was observed at 10 days in the non-inoculated silage along with rapid growth of undesirable Hafnia. L. plantarum inoculation inhibited growth of Hafnia at 10 days in the non-wilted silage. Clostridia fermentation occurred in the non-wilted silage at 90 days, as indicated by an increased pH, formation of butyric acid (BA), and apparent abundance of genera belonging to Clostridia. L. plantarum inoculation inhibited BA accumulation and growth of Garciella in the non-wilted silage at 90 days as compared with the non-wilted silage without inoculation, but had little effect on the growth of Clostridium sensu stricto. Overall, the high moisture content of the non-wilted alfalfa silage led to rapid consumption of WSCs and growth of harmful microorganisms at the early stage of ensiling, resulting in poor fermentation quality. Wilting and L. plantarum inoculation both improved fermentation quality and inhibited the growth of spoilage microorganisms in alfalfa silage, while L. plantarum inoculation alone failed to achieve optimum fermentation quality of non-wilted alfalfa silage.

Perilla frutescens as potential antimicrobial modifier to against forage oat silage spoilage

“…Hafnia is a gram-negative genus of the family Enterobacteriaceae , which able to grow under anaerobic conditions as well as low pH environments ( Wang et al, 2021 ). As undesirable bacteria, they compete with lactic acid bacteria for nutrients in both anaerobic and aerobic fermentation, resulting in large nutritional loss ( Yang et al, 2021 ). In addition, some species of Hafnia such as Hafnia alvei could transform nitrogen from protein in silages into NH 3 ( Yang et al, 2021 ).…”

“…As undesirable bacteria, they compete with lactic acid bacteria for nutrients in both anaerobic and aerobic fermentation, resulting in large nutritional loss ( Yang et al, 2021 ). In addition, some species of Hafnia such as Hafnia alvei could transform nitrogen from protein in silages into NH 3 ( Yang et al, 2021 ). Hence, the higher relative abundance of Hafnia alvei in CK groups, especially in aerobic exposure, could explain their higher DM loss and NH 3 -N.…”

Natural fermentation quality, bacteria, and functional profiles of three cuttings of alfalfa silage in a year in Inner Mongolia, China

“…High-throughput sequencing has been widely used in recent years to illustrate the microbial community structure in the alfalfa ensiling process ( Guo et al, 2018 ; Yang et al, 2020 , 2022 ), and research in this area has primarily focused on the microbial communities in alfalfa silage. Microbial communities are influenced by many factors such as additives ( Yang et al, 2020 ), moisture content ( Yang et al, 2022 ), and silage density ( Sun et al, 2021 ). The dominant genera changed with the different inoculated lactic acid bacteria (LAB) additives ( Ogunade et al, 2018 ; Fan et al, 2021 ).…”

“…Only limited research has focused on the microbial communities of wilted alfalfa (W). Previous studies have indicated that wilting may affect the abundance of epiphytic microbes ( Agarussi et al, 2019a ), and that wilting inhibited the growth of spoilage microorganisms in the early stage of ensiling, which resulting in good fermentation quality ( Yang et al, 2022 ).…”

“…Bacterial populations vary according to geographic area, climate or growing stage ( Duniere et al, 2013 ). Previous studies have reported that wilting of fresh alfalfa before ensiling may improve the fermentation quality of the silage ( Agarussi et al, 2019a ; Yang et al, 2022 ). All of these studies, however, used only one cutting of alfalfa, for example the first cutting ( Li F. et al, 2020 ; Wang B. et al, 2020 ), the second cutting ( Wang et al, 2021 ) or the fourth cutting ( Li R. et al, 2020 ).…”