Bacterial community dynamics during the ensilage of wilted grass

Grass silage is the product formed by a natural lactic acid bacterial fermentation when grass is stored under anaerobic conditions, and represents an important ruminant feedstuff on farms during winter. Of the two commonly employed methods of ensiling forage, baled silage composition frequently differs from that of comparable precision-chop silage reflecting a different ensiling environment. The aim of this study was to investigate the dynamics of the silage fermentation in wilted grass and between ensiling systems.

Fermentation dynamics were examined using traditional methods of silage analyses, including microbial enumeration and analysis of fermentation products, and culture-independent terminal restriction fragment length polymorphism (T-RFLP). A successful fermentation was achieved in both systems, with the fermentation (increase in lactic acid bacteria and lactic acid concentration, decrease in pH) proceeding rapidly once the herbage was ensiled.

Under controlled conditions, little difference in silage quality and microbial composition were observed between ensiling systems and this was further reflected in the T-RFLP community analysis.

T-RFLP proved a potentially useful tool to study the ensilage process and could provide valid support to traditional methods, or a viable alternative to these methods, for investigating the dynamics of the bacterial community over the course of the fermentation.