Additives assist with rapid and high quality fermentations

He says it is possible to reduce the impact of poor harvest conditions by understanding how different dry matter crops ferment and modifying crop management accordingly.

“The weather at first cut can play havoc with silage making and last year’s wet conditions in mid- and late-May were blamed for some disappointing forages.

“Wet grass turned into low dry matter silage with disappointing intake characteristics. Wet grass presents some specific fermentation challenges, which, if overcome, allow better quality silage to be produced.”

Mr Berni says grass harvested in the wet will have low dry matter. These crops often have less opportunity to wilt and the quality of wilt will be reduced if ambient conditions are cool and damp.

“Grass harvested in the wet will have a low sugar content,” he says. “Furthermore, the natural populations of lactic acid bacteria can be unpredictable. This means the grass is short of the two factors essential for a rapid fermentation, yet in order to preserve lower dry matter grass and achieve a stable fermentation it is essential to achieve a much greater pH drop than for drier grasses.”

A significant pH drop is necessary to prevent the proliferation of the undesirable bacteria responsible for secondary, butyric fermentation so often associated with wet silages, says Mr Berni. Rapid fermentation also reduces protein breakdown, improving forage feed value.

To help ensure a rapid and effective fermentation, Mr Berni recommends using an additive formulated specifically for low dry matter crops. These will contain high levels of lactic acid producing bacteria.

“Farmers should look for an additive containing enzymes that help breakdown fibre, improve forage digestibility and increase sugar availability,” he says.

To ensure fermentation starts quickly, the clamp should be well consolidated and sealed, although it should not be difficult to consolidate and roll wet material.

Consolidation, however, can be a problem with silages at the other extreme of dry matter and Mr Berni believes dry silages present a different range of challenges.

“Higher dry matter grass does not require such a significant drop in pH to undergo preservation, the rule of thumb being the lower the dry matter the lower the pH required to stabilise the silage.

“The big problem is actually ensuring an aerobic stability, as the crop is hard to consolidate and at risk from yeasts and moulds, which will reduce feed value.”

Mr Berni recommends an additive designed to work on drier silages. These will contain a high level of Lactobacillus buchneri 40788, which produces a number of metabolites that combine to prevent the growth of yeast and mould in the clamp.

“With dry silages a high level of lactic acid can be a bad thing. When oxygen is introduced into the clamp, yeasts actually use the lactic acid as a feed source and will multiply quickly, raising the pH and causing the clamp to heat up.

“If a dry crop is being made the aim must be to roll and seal the clamp well to prevent oxygen in. This combined with an additive ensures an effective pH drop and the control of yeast will lead to better quality forage.”

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