Assessing the impact of various ensilage factors on the fermentation of grass silage using conventional culture and bacterial community analysis techniques

Abstract

Aims: Grass silage is an important ruminant feedstuff on farms during winter. The ensilage of grass involves a natural lactic acid bacterial fermentation under anaerobic conditions, and numerous factors can influence the outcome of preservation. The aim of this study was to investigate the effect of dry matter concentration, ensiling system, compaction and air infiltration on silage bacterial community composition. Methods and Results: The impact of these factors was examined using conventional methods of microbial analysis and culture‐independent Terminal Restriction Fragment Length Polymorphism (T‐RFLP). Silage fermentation was restricted in herbage with a high dry matter concentration, and this was reflected in a shift in the bacterial population present. In contrast, ensiling system had little effect on bacterial community composition. Air infiltration, in the absence of compaction, altered silage bacterial community composition and silage pH. Conclusions: Dry matter concentration and the absence of compaction were the main factors affecting silage microbial community composition, and this was reflected in both the conventional culture‐based and T‐RFLP data. Significance and Impact of the Study: T‐RFLP proved a useful tool to study the factors affecting ensilage. Apart from monitoring the presence or absence of members of the population, shifts in the relative presence of members could be monitored.

Sensitivity ofMycobacterium aviumsubspparatuberculosis,Escherichia coliandSalmonella entericaserotype Typhimurium to low pH, high organic acids and ensiling

“…; McEniry et al . ). The safety of this important livestock feed depends on the susceptibility of deleterious and pathogenic organisms to the low pH and OA produced during the ensiling process.…”

Bacterial and fungal core microbiomes associated with small grain silages during ensiling and aerobic spoilage

“…Numbers of viable LAB tend to decrease during storage with the exception of some heterofermentative species such as Lactobacillus buchneri, which convert lactic acid into acetic acid and have been identified in corn silage a month after fermentation [60]. Culture independent techniques such as DGGE, T-RFLP or LH-PCR have been used to characterized silage bacterial communities and shown a predominance of Lactobacillus , Lactococcus and Pediococcus during ensiling [61, 62]. These observations are in accordance with our results as the core bacterial microbiome after 90 day of fermentation in silage showed reduced diversity and was largely dominated by members of the Lactobacillales.…”

Bacterial community dynamics during ensiling of perennial ryegrass at two compaction levels monitored by terminal restriction fragment length polymorphism

“…Especially the latter approach has been shown to be highly valuable for accessing the impact of various ensilage factors on the development of the bacterial community in the silage (McEniry et al . , ).…”