On-farm consultations offer route to better silage

With strong interest in producing more milk from forage, Volac is offering a number of free consultations to help improve silage-making under its Cut to Clamp initiative. Find out more...

Darren Ward

The offer of a free consultation to help farmers produce consistently better silage may sound too good to be true. But that’s what leading animal nutrition and forage preservation company, Volac, is offering.

It’s all aimed at helping producers get more milk from silage.

“There’s a huge amount to be gained from making better silage,” says Darran Ward, one of Volac’s nationwide experts conducting the consultations.

“Benefits can include spending less on bought-in feeds, improvements in cow health from a more forage-based diet, and the satisfaction of making your business more self-sufficient by feeding more of what you grow.

“The consultations provide practical pointers to improve silage quantity or quality at various stages of the silaging process – including cutting, wilting, treating, harvesting, clamping and even feeding.”

In essence, Mr Ward says consultations involve three steps:

  1. Silage sample analysed and results interpreted
  2. Visual inspection of the clamp
  3. Detailed understanding of the silage-making process

“By combining all three, a comprehensive picture is built up to unearth areas for improvement,” he adds.

1. Silage analysis interpretation

Paperwork smlThe Cut to Clamp consultation simplifies the silage analysis into a user-friendly summary

Although farmers are used to seeing silage analyses, the Cut to Clamp consultation goes further by simplifying results into a user-friendly summary in two key areas, says Mr Ward:

Nutrient quality – for a picture of what the animal can take from the silage nutritionally – based on factors such as digestibility, energy content, sugar and crude protein.

Keeping quality – for a picture of the efficiency of the preservation – based on factors such as fermentation quality and ammonia production, but also others.

Nutrient quality

“As an example of nutrient quality, if the silage scored low for digestibility, we would ask about the quality of the grass to begin with,” says Mr Ward. “Is more regular re-seeding needed? Also, we’d look at cutting date, because after heading the digestibility of grass falls by about 0.5% a day.

“Similarly, the protein content of grass will decline as the season progresses. So again, this gives an indication of plant maturity when cut. Additionally, a breakdown product of protein – ammonia – gives a useful measure of keeping quality.”

Keeping quality

Explaining this, Mr Wards says a high ammonia content is an indicator of a poor fermentation, because protein hasn’t been fully preserved.

“We also want a high sugar content. Low sugar content can be an indicator of a poor fermentation carried out by the wrong type of bacteria, as these produce the wrong type of acids as well as carbon dioxide from the sugar, which wastes the silage’s energy.

“We want a fermentation that produces the right type of acid to ‘pickle’ the grass into silage – lactic acid. This uses up less sugar and is more efficient. So, as well as the pH of the silage, we also look at the proportion of lactic acid to less desirable acids – such as acetic, propionic or butyric acids.

“Good silage would have five times as much lactic acid as other acids. A bad-scoring silage could have a ratio as low as 1:1.”

2. Clamp inspection

As well as the silage analysis, a lot is gleaned by inspecting the clamp, Mr Ward says.

Tidiness and temperature

“We’ll look at how uniform and tidy the silage is in the clamp. An untidy silage face increases the chance of air penetrating, resulting in wastage from aerobic spoilage, characterised by heating. So, we’ll check the temperature at several points with a probe.

“Also, how tidy is the floor? It should be clean right up to the edge of the silage to avoid contaminating the face with old silage.”

Using temperature probe sml

As well as testing for temperature, the degree of difficulty of inserting the thermometer probe into the silage indicates how well it’s been consolidated, says Darran Ward.

Colour, texture and smell

Visually, Mr Wards says silage colour will be checked, with olive green an indicator of good grass silage, while brown could mean a poor fermentation.

“We’ll also look at the amount of stem and leaf material in the silage. You want mainly leaf because stems are less digestible. Excess stem can mean cutting date was too late.

“You also don’t want it to smell like vinegar or sickly sweet, but to have a nice, clean smell about it,” he adds.

Silage should have a clean smell about it, says Darran Ward, and not smell like vinegar or sickly sweet.


To assess consolidation, Mr Ward says straight, horizontal lines showing in the layers of silage are a good sign. Wavy lines indicate uneven consolidation.

“The degree of difficulty pushing the temperature probe into the silage also indicates how well it’s been consolidated, while the shoulders, which are harder to consolidate, will be visually checked.

Wavy silage layers smlWavy lines in silage layers indicate uneven consolidation.

Sheeting and sealing

“For sheeting, we’ll check whether side sheets have been used, and check how many layers are on the top? Many farmers think they don’t need side sheets in a concrete clamp, but porous concrete is not as good as plastic for keeping air out.

“Ideally, we’d look for an oxygen barrier film on top of the silage, with side sheets overlapping as far as possible over the top, then at least one black plastic sheet on top, and the whole thing properly weighted.

“But it’s also important that sheets are rolled back from the clamp face, once opened, to divert rain water from the top of the clamp from penetrating into the face.”

Side sheets should extend all the way down to the floor, says Darran Ward, because porous concrete is not as good as plastic for keeping air out.

No side sheet sml

3. Silage production assessment

The final piece of the jigsaw is to discuss with the farmer how silage is currently produced.
2669 039

Consultations include a discussion with the farmer to find out how silage is currently produced.


“Starting with cutting, we’ll review cutting date and height to see if there’s anything out of order, and whether a mower-conditioner has been used to help speed up wilting. That’s because the faster you wilt to the target 28-32% dry matter, the less sugar is used up by the plant continuing to respire.


“We’ll also review the full wilting process – for example has a tedder been used. Most moisture is lost through the pores in grass leaves – the stomata – which can lose up to 100 litres of water per tonne per hour. But they only stay open for two hours after cutting. Tedding within two hours of cutting gives better quality.


“You also need to use the right chop length for the stage of cutting and for your target % dry matter, so that you get the best consolidation in the clamp.

“We also consider the harvest machinery. Was it a rapid forage harvester, or a slower trailed harvester or forage wagon? All these affect how long it takes to get the crop in the clamp.”


For treating, Mr Ward says he examines whether the right type of additive has been used. “Some people using a silage additive can suffer heating and mould in the silage but have applied a fermentation-only additive which will have no effect on aerobic stability. Therefore, ensure you are using the right product for the correct outcome.

“Also, often an additive is used as a type of insurance. But think of it more as proactively managing the preservation process,” he adds.


“We’ll also ask how the clamp was filled – was it in thin enough layers to aid consolidation, and was it rapidly sheeted?


“Finally, we look at how the silage is fed. For example, are you using a shear grab, and do you roll the top sheet back, rather than leave it hanging over the face, as the latter encourages spoilage from yeast and moulds?”

Removing silage smlConsultations cover all the way through to feeding.


By conducting the consultation, Mr Ward says it becomes possible to pinpoint areas for improvement for making next season’s silage, but it can also provide tips to get more from the silage already in the clamp.

“Ultimately, the more milk produced from silage and forage, the better,” he adds.

Find out more about the Cut to Clamp initiative or book your free silage consultation.