16 February 1996

Additive can cut aerobic spoilage

AEROBIC spoilage can be reduced in opened clamps using a sulphite salt-based additive according to recent CEDAR, Reading University research.

The work sponsored by additive manufacturer Thomas and Fontaine, showed that over six days the pH of the control silage increased from 3.8 to 5.8 and its temperature rose resulting in a 13.6% loss in dry matter. The treated silage stayed at pH 3.8 and at ambient temperature, claims the companys Dr Gerard Thomas.

Prof Mike Wilkinson, De Montfort University, Lincoln claims there has been a trend towards higher dry matter grass silage to reduce effluent loss and because it has higher sugar levels that are highly digestible in the rumen.

However, he warns high dry matter silage is more difficult to consolidate and is prone to yeasts, moulds and heating that causes dry matter losses. However, wet silage and clamps that are used too slowly, for example, for buffer feeding, also risk aerobic deterioration.

Fermented whole-crop forage is also at risk due to its high dry matter and low sugar content, he adds.

"Heating is not always seen at the face of the silo," says Prof Wilkinson. "The face can be cold due to evaporation or rain, so it is getting wetter or dryer. But 0.5m back from the face when air is penetrating is where the damage occurs.

"Choosing the right additive is spending money to buy time. It is difficult to say how much time for this depends on individual silages. But these extra few days could be critical," he says.

Prof Mike Wilkinson of the De Montfort University, Lincoln, says:"High dry matter silage is more prone to aerobic spoilage."