Check out the best way to make superior quality grass silage

Neutral Detergent Fibre (NDF) was quite high at 48.8%, on average, which means silages – especially later first cuts – were quite stemmy.

In addition, lactic acid was low and volatile fatty acids were high at 30%. This results in a restricted fermentation and can lower cow intakes.

While last year’s challenging weather conditions caught some farmers out, Dr Robin Hawkey, senior nutritionist at Mole Valley Farmers, stresses simple steps can be taken to improve silage quality this season.

“Silage is expensive to make regardless, but getting it wrong can be very costly. On top of that, there is the grief and stress of the cows not milking well enough.

“With the best will in the world, the weather has an impact but failing to plan is planning to fail.”

Dr Hawkey and colleagues have highlighted how farmers can plan for a good quality first cut.

1. Carry out a silage analysis

Not only does this tell farmers what is going on inside the clamp, and how it will feed, it can help to pinpoint areas for improvement in the silage-making process.

For example, the presence of mould can suggest changes must be made to the sealing of the clamp while low levels of protein can point to crop under-nutrition.

2. Test grass before cutting

Rather than go by traditional dates, farmers should test grass one week before they plan to cut it to make sure it is ready.

One of the most important parameters to look at, is the level of nitrates in the grass. Excess nitrogen from slurry and fertiliser is a risk because it can depress grass sugars which can cause poor crop fermentation.

“Having that knowledge will automatically help you to make better silage,” says Lisa Hambly, head of forage and grassland at Mole Valley Farmers.

Assessing the dry matter of the samples will also help to guide the cutting and wilting strategies.

Carry out fresh grass tests one week before cutting

Take representative samples of what you are cutting or sample highest risk fields – those last applied with nitrogen/high levels of slurry

Sugars need to be high

Nitrates should be as low as possible.

Ensure the right silage additive for the ration dry matter produced and be prepared to change additive if the dry matter is significantly different than anticipated.

3. Quality or bulk?

What is needed? Good-quality silage or more of it? This will determine when the grass should be cut.

“If bulk is needed it may be better to cut later. It is a very simple question, but it needs answering. You cannot ration fresh air,” warns Dr Hawkey.

He says farmers need to calculate how many tonnes of grass silage they have left over and consider how the ration might differ on the year.

He adds: “Have you got the same acreage of maize as last year and how might that affect how much silage is needed?”

The ratio of grass to maize silage is also worth considering as it may affect the quality of grass silage needed, he adds.

4. Harvesting

Do not leave grass on the ground for more than 24 hours.

Cutting grass in the morning and tedding it straight away can speed up the wilting by five times.

“All too often grass is left overnight and brought in at a much higher dry matter and the grass is leaching sugars which affect fermentation,” says Volac silage expert Ken Stroud.

“If it is raining, just get it in. It is better to be in the pit at 24% dry matter than left in the field for days,” he adds.

Adequate chop length is critical to achieving good clamp consolidation.

The target should be 15-25mm with the chop length made 4-5mm longer if silage is 25% dry matter, for example, and shorter if a dry matter of 30% is achieved.

For silage that is 20% dry matter or below, a chop length of 30-35mm or even longer may need to be considered.

If there is a high maize silage inclusion in the total mixed ration (TMR), a slightly longer chop might be needed to supply adequate fibre for rumen health, advises Dr Hawkey.

“If grass is lush and it is too short it can be more prone to slippage, depending on the clamp dimensions,” explains Mr Stroud.

In this instance, it might require two or three passes with the tedder to speed up the wilting process.

5. Clamping

Ensile grass in layers of 10-15cm and use sufficient weight to consolidate the pit.

For every 100t of grass silage entering the clamp, use 25t of machinery (usually two tractors – one with a buck rake and another with a compactor). Narrow tyres give a better compaction than wide ones.

Do not roll each layer for more than 30 minutes, regardless of quality, because this can destroy the structure of the grass and force air into the clamp.

Grace Burrows, product manager at Mole Valley Farmers, says: “Oxygen is the enemy – it creates higher losses and there is a greater risk of anaerobic spoilage during feed out.”

Clean the clamp before re-filling

Use cling film to achieve a sufficient seal and prevent oxygen from entering

Use side sheets

Ensure the clamp is evenly weighted with mats or tyres, for example.