Ensiling allows livestock producers to offer nutrient-rich forage in rations year-round. Understanding what happens after the silo — tower, bunker or pile — is ensiled can help producers avoid common pitfalls that too often reduce the quantity and quality of forage available to feed.
Even after plants are harvested, their cells continue to breathe — or respire. During this stage, plant sugars in the freshly harvested crop are broken down into carbon dioxide, water and heat. This uses up the sugars that are required for the ensiling fermentation, reduces dry matter (DM) recovery and can compromise silage quality. Respiration will continue until the oxygen supply is depleted. Packing and sealing crops helps reduce the oxygen available, minimizing ongoing respiration and reducing the potential for yeast and mold growth.
Once the oxygen is gone, fermentation really takes off. In an efficient ensiling fermentation, pH is lowered quickly due to the production of lactic acid by lactic acid bacteria (LAB). These bacteria are naturally present on the forage at harvest, but in numbers that can vary greatly, which is one reason why using a research-proven forage inoculant is recommended. The lactic acid bacteria Pediococcus pentosaceus 12455 provides an efficient, fast fermentation, especially when fueled by sugars generated by high-activity enzymes. In addition, specific types of the bacteria can help prevent heating and spoilage: Lactobacillus buchneri NCIMB 40788 has been reviewed by the FDA to allow a claim of efficiency in preventing heating and spoilage.
Different crops that are ensiled have varying levels of sugar and protein content, which affects the time it takes to achieve a low pH. On the other hand, some forages are simply more prone to aerobic spoilage. For example, although corn silage can achieve a stable pH within the first week, it is best to wait a few months after ensiling to feed-out. This will result in better aerobic stability. Material treated with L. buchneri 40788, plus ensiling for eight to nine months or more, can increase the starch digestibility in whole-plant corn silage, earlage, snaplage and high-moisture corn.