How silage additive helps ensure maize quality

• Spoilage risk in warm wet season

• Helps combat yeasts and moulds

• Treated silage is more palatable

A silage additive to aid maize forage fermentation is likely to pay dividends this autumn – helping to prevent significant mycotoxin accumulation.

A good additive will restrict the development of unwanted yeasts and moulds. But a separate specialist treatment should be used where high mycotoxin levels are already present in the harvested crop.

With this year’s warm, damp growing conditions potentially favouring moulds and mycotoxins in maize, using an additive could be particularly timely, explains Volac silage scientist Mark Leggett.

‘Clear evidence’

But mycotoxin levels were 98% lower hen an additive was applied to the crop at ensiling. This is important because mycotoxins are associated with poor rumen function, ketosis and immune suppression in livestock.

Volac research suggests clear evidence that the company’s Ecocool additive can significantly improve silage quality due to the way it acts against yeasts and moulds during exposure to air, explains Dr Leggett.

Yeast and mould growth generally occurs following exposure of silages to air in a process called aerobic spoilage – a cascade of events triggered initially by yeast breaking down the all-important silage lactic acid.

“In turn, this raises silage pH, which allows mycotoxin-producing moulds to grow in the silage,” explains Dr Leggett. “The clearest sign that silage is suffering aerobic spoilage is usually the production of heat.

A little over a month after ensiling, yeast levels in the treated silage were 96% lower than in the untreated silage. Further measurements showed the untreated silage took 1.5 days to start heating when exposed to air, compared to 3.5 days for untreated silage.

“If silage is heating, it’s losing a massive amount of energy,” says Dr Leggett.

Although the crop at ensiling contained no detectable mycophenolic acid or roquefortine C mycotoxins, deoxynivalenol (DON) mycotoxin levels produced by Fusarium moulds, were higher than 10,000 parts per billion.

Better digestibility

“With DON already present in the harvested crop, it is important to note that ensiling, with or without the additive, did not reduce these very high levels of DON contamination,” says Dr Leggett.

DON levels rose to more than 17,000 ppb in the untreated and treated silage after ensiling and exposure to air. A fourth mycotoxin, zearalenone (ZON), was also detected in the silage but at low levels.

In cases like this, a specialist mycotoxin remediation treatment, such as Ultrasorb from Volac, would be needed to reduce the mycotoxin burden of such silages in the final feed when fed to livestock, suggested Dr Leggett.

Digestibility of the treated maize silage was 4% higher than the digestibility of the untreated silage by as much as 4%, after exposure to air. This is significant because higher digestibility is associated with improved milk yield.