How forage analysis can improve winter sheep feed planning

Sheep farmers were reminded of the importance of getting forage analysed to create a winter feed plan, at the recent Virtual Celebration of Sheep Farming.

Speaking at a webinar organised by the National Sheep Association, Paul Mardell, technical manager from Carrs Billington, stressed the value of getting grass silage analysed to avoid unnecessary expenditure on extra compound.

“Forage is the most important feed for the rumen – it’s absolutely vital. Grass is a forage that provides more than 90% of the energy required in the majority of our feed systems,” said sheep farmer Mr Mardell. However, as grass growth slows into the winter months, a feed budget will ensure sheep nutrition requirements can be met.

“There is no point spending money on a high-protein compound if we don’t really need it.”

Mr Mardell, who is also chairman of the British Sheep Dairying Association, shared some metrics sheep farmers should be looking for on a forage analysis report as well as best practice tips on sampling.

See also: Tips to help livestock farmers develop a winter feed budget

Optimum grass silage

Key targets to look for on a report include:

    1. Dry matter 30-40%
      Low dry matter silages tend to be wet with a high acid load, which can reduce intakes, while silages too high in dry matter  can make the forage more susceptible to heating and spoilage
    2. D-value 60+
      This is the digestibility of the forage, which is directly related to the timing of ensiling
    3. Metabolisable energy (MJ/kg DM) 10.5+
      This is the energy available to the animal after losses in the digestion process (such as urinary losses)
    4. Crude protein 12%+
    5. pH 3.8-4.2
    6. Lactic acid 60-80g/kg
    7. Sugar More than 50g/kg
    8. Neutral detergent fibre (NDF) 420-500g/kg
    9. Ash No higher than 10-12%. A high ash content could indicate some soil within that sample, which could present a listeriosis risk.

When and how to take the sample

Because the forage quality will change as time progresses, it is beneficial to get numerous samples analysed across the feeding season, to ensure the feed plan is still meeting ewe requirements.

Big bale silage Ideally, the sample should be taken from a number of bales from across the season and multiple fields to give a representative sample. A small amount should be pulled from each bale and mixed.

Clamp silage Starting in the top left corner of the clamp face, a small amount should be taken from multiple places, working across the clamp in a W-shape.

The cost-benefit of better-quality silage

Mr Mardell explained to webinar attendees how the financial benefits of better-quality silage can add up in a flock, with a superior-quality silage saving 13p a ewe a day in feed costs.

The calculations are based on a:

  • 70kg twin-bearing ewe at three weeks pre-lambing,
  • Ewe’s energy requirements of 15.3MJ/day,
  • Concentrate supplement of 12.5ME, costing £260/t.


Poor-quality forage – 9.3ME

Very good forage – 11.3ME

Ewe’s forage intake

0.84kg DM (1.2% of bodyweight)

1.19kg DM (1.7% of bodyweight)

Energy provided to the ewe from forage



Energy shortfall from daily requirement



Ewe compound required to supplement energy shortfall a day



Cost of supplementation a ewe