Why a proven additive belongs in this year’s grass silage plan

21 May 2025

With potentially £35,000-£40,000 (€41,000-€47,000) worth of silage in a 1,000 tonne clamp, isn’t it worth giving it the best possible preservation?

That is the message from Volac technical business manager Ken Stroud, who says without an additive, the quality of a silage’s fermentation – and therefore how well its nutrients and dry matter (DM) are preserved – are left very much open to chance.

“Fermentation is essentially a ‘pickling’ process which protects silage against the growth of unwanted microbes,” explains Ken.

“With grass ensiled without an additive, you’re dependent on whatever bacteria are naturally present on the grass to carry out the fermentation. These might include some good bacteria. But there are also likely to be bad ones present – in particular bacteria from slurry or soil.

“While the good bacteria might ferment the sugar in the grass to lactic acid – which is what you want (see later) – these unwanted bacteria produce compounds that are much less desirable, such as ethanol and butyric acid.

“Some of these compounds are not only less effective at ‘pickling’ the grass – which allows other undesirable bacteria to feed on the silage for extended periods of time – they also waste some of the energy and DM contained in the sugar that they ferment. For example, certain bacteria can waste 17% of the energy in the fermented sugar and 41% of its DM. Carbon dioxide is also produced, which is a greenhouse gas.”

Ken says a particularly unwanted fermentation occurs when clostridia bacteria from soil are present. These convert lactic acid into butyric acid, a process which not only wastes even more energy and DM, but also leads to unpalatable silage, he adds.

Ecosyl additive

By contrast, when the proven additive Ecosyl is applied, he says it delivers a million beneficial Lactobacillus plantarum MTD/1 bacteria per gram of grass treated. This special MTD/1 strain is important because it is highly efficient at fermentation, resulting in rapid production of lactic acid, he points out.

Lactic acid is what you want because it retains more than 99% of the energy contained in the original fermented sugar and all of its DM. But more importantly, it also produces a rapid ‘pickling’ effect, so the growth of undesirable bacteria is quickly stopped. 

“With fewer nutrients consumed by these undesirable microbes in Ecosyl-treated silage, more are available to the animal. So much so, Ecosyl-treated silage has been shown to be higher in true protein and higher in metabolisable energy (ME) – for example containing 11.3 MJ/kgDM versus 10.6 MJ/kgDM in untreated silage. 

This means more energy is available for production of milk or meat, and research on a range of forages showed cows fed silage preserved with Ecosyl yielded an average of 1.2 litres more milk/cow/day than cows fed untreated silage.

“Other research has shown that while grass ensiled without an additive lost a tenth of its DM, in grass silage conserved with Ecosyl, DM losses were more than halved. 

“With these benefits in mind, and the value of silage, the cost of protecting it with Ecosyl is minimal,” Ken concludes.

Discover how Ecosyl could improve the quality and value of your silage this season.