Silage Fermentation And The Use Of Inoculants

Since the dawn of time there has been a need to provide a good quality supplementary feed source in times when grass or other forage options are limited. In modern agriculture, silage production forms an integral part of most livestock production systems.

- Delia Thomson

The goal of ensiling is to stabilise the crop as quickly as possible through the action of lactic acid bacteria (LAB) to preserve the original plant nutrient composition and to ensure minimal losses. With all the effort and cost involved in growing a good forage crop, you do not want a large quantity (sometimes up to a third) of it to be lost during the ensiling and fermentation process.

The ensiling and fermentation process is driven by microbial (epiphytic) populations found on the crop at harvest. The fermentation process has a significant effect on both the quality and quantity of stored feed that will be available to livestock. This process involves both aerobic and anaerobic bacteria. Fermentation is often divided into six phases, which start from harvest (aerobic) through storage (anaerobic) and ends with feed out (aerobic).

Harvest until oxygen depletion

Phase 1 of fermentation occurs from harvest until either all the oxygen has been removed/utilised and anaerobic conditions begin, or the supply of water-soluble carbohydrates (WSCs) is depleted. This phase should take only a few hours under ideal conditions and is driven by cell respiration and aerobic organisms, which utilise sugars to form metabolites. The most notable change during this phase is an increase in temperature due to the production of heat.

Carbon is lost during this phase through gaseous carbon dioxide that is released into the atmosphere (this loss in carbon causes a loss in dry matter [DM] in silage). It is because of this process that management practices at this stage aim to expel oxygen from the storage unit as quickly as possible to reduce DM losses and minimize the growth of aerobic silage spoilage organisms such as yeasts and