Ask the Silage Dr: Optimum alfalfa-grass dry matter content

Q. I'm planning to harvest an alfalfa-grass mix for silage. What is the best dry matter content to ensile at?

A. The optimum dry matter (DM) content for alfalfa, alfalfa-grass mixtures and grass (as well as other forage legumes) can all be considered together. Table 1 below shows the best harvest stage and DM level for alfalfa based on the type of storage structure you plan to use.

These types of forage crops contain sugars that start to degrade immediately after mowing, and sugars are needed to drive the ensiling fermentation. So, the key to high-quality hay crop silage is to dry the crop to the proper DM level for ensiling in your respective storage structure as quickly as possible.

Leaving the mowed forage in wide swaths will result in much faster drying and better conservation of plant sugars.

The potential for a poor fermentation, and butyric acid formation in low DM haylages is a greater problem if forages are left in the field overnight. The mown plant is still actively respiring and burning sugars. This risks slowing the growth of lactic acid bacteria, resulting in a slower pH drop, which in turn allows clostridia to take over, producing a butyric silage.

Using an inoculant containing efficient homolactic bacteria such as Pediococcus pentosaceus 12455, together with enzymes to generate sugars, results in a fast fermentation and inhibition of clostridia and other undesirable microbes.

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