Right conditions key for multi-cut grass

Mark Leggett: “Because of the shorter window between cutting, there is a risk of elevated nitrogen levels in a multi-cut crop which can slow down the decline in pH during ensiling.

“Potentially higher protein levels found in younger grass can also slow down or resist the pH change taking place, a process that ideally needs to happen as quickly as possible as a low pH is key to controlling the activity of bad bacteria.

“Slurry applied to the crop also has less time to wash off the leaf, which creates a risk of contaminating the fermentation with bad bacteria."

Philip Jones: “We found this during the trial, with slurry bacteria counts on untreated samples found to increase throughout the season.

“The combination of large numbers of slurry bacteria with a potentially slow decline in pH creates a ‘perfect storm’ leaving the forage vulnerable to high DM losses."

Mark Leggett: “Despite the exceptionally dry conditions of last summer which meant cut three, taken on July 3 2018, was ensiled at 50 per cent dry matter, we were able to achieve higher lactic acid bacteria counts when we treated with an additive compared to levels which were naturally present in the untreated samples.

“Consequently, pH levels in the treated samples declined rapidly, within the first one to three days after ensiling, whereas untreated samples struggled to decline, even after one week and beyond. It did not reach the same levels as the treated silage, even after three months.

“This slow fermentation therefore gave slurry bacteria the opportunity to multiply in the untreated silage ultimately resulting in high dry matter losses, whereas the fast fermentation seen in the treated silage prevented this from happening.”

Philip Jones: “We also saw clostridial activity in untreated samples, creating butyric acid, a foul smelling by-product which can reduce silage palatability. In the treated samples there was no butyric acid present, as the clostridia were suppressed by the low pH.”

Mark Leggett: “Challenging fermentation conditions were visible on samples from all of the cuts taken, which would create the potential for dry matter losses in the clamp and the risk of a lot of butyric silage in a real life situation if silage was left untreated."

Philip Jones: “Applying an additive means control over the fermentation process, as well as consistency every time rather than relying on what the natural populations of bacteria are at any given time which is likely to range hugely due to external factors.

“For those chasing yield and quality, it is surely desirable to have this level of control.”