Quality Grass Silage Guide

This quick reference guide to silage making assumes that soils are free from compaction and have optimum nutrient status. It is a prompt to seek further information if required.

Important considerations when selecting a grass mixture for silage making should include:

  • Planned duration of the ley
  • Number and timing of cuts in a season
  • Silage only or dual purpose
  • Quantity and quality
  • Clover or no clover
  • Is drought tolerance required

Addressing these points will help ensure that the type of mixture is fit for purpose. Mixtures for silage production will contain a number of ryegrass varieties (perennial, hybrid or Italian), with the possible addition of an alternative grass species, such as timothy, and white or red clover.

  • Ensure all varieties are high ranking on the latest Recommended List
  • Consider the relative merits of diploid and tetraploid varieties

Diploids are more persistent and create a denser sward, better suited to wetter conditions and where long-term grazing is also required Tetraploids have a more upright growth habit and can be faster establishing.

  • Ensure the heading date range within the mixture is as tight as possible (1 week optimum) and coincides with target cutting dates in order to maximise quality

When making silage, it is usually the case that as quantity increases, quality decreases. This is because the more mature (and higher yielding) crop will have lower nutritional value, for reasons explained earlier in this guide.

There is therefore an inevitable compromise, with decisions on when to cut best determined by the class of livestock to be fed and stock performance targets.

For maximum yield without significant compromise of quality, most crops are best cut approximately one week before heading.

Wilting to achieve an optimum silage dry matter of 30-35% (clamp) and 35-40% (bale) should ideally be quick and short, so a maximum of 24 – 36 hours.

  • Using a mower conditioner will increase the speed of wilting and reduce losses of sugar, protein and dry matter
  • Leaf pores only remain open for two hours after cutting, when speed of moisture loss is five times greater than after pores close – so spread the crop quickly after cutting
  • Spread the crop over 100% of the field area, again to increase the speed of wilting

Silage clamps and bales

Quality grass silage can be made in both clamps and bales, and both systems have their place on modern livestock farms. The choice depends on individual farm circumstances and a range of variables. Silage additives will not salvage poor quality forage, but when the right product is selected for the right purpose they may help make good silage even better.

Making good silage in clamps

  • Ensure the forage harvester is blowing all chopped material into the trailer
  • Set forage harvester chop length according to grass dry matter content
  • Sheet the clamp side walls
  • Consider using a ‘clingfilm’ as a second top sheet to reduce oxygen ingress
  • Ensure all machinery entering the silage pit have clean wheels
  • Fill the clamp quickly in thin layers whilst ensuring sufficient compaction
  • Sheet down quickly after finishing
  • Weigh down the top sheet sufficiently
  • Using a mower conditioner will increase the speed of wilting and reduce losses of sugar, protein and dry matter
  • Leaf pores only remain open for two hours after cutting, when speed of moisture loss is five times greater than after pores close – so spread the crop quickly after cutting
  • Spread the crop over 100% of the field area, again to increase the speed of wilting

Silage clamps and bales

Quality grass silage can be made in both clamps and bales, and both systems have their place on modern livestock farms. The choice depends on individual farm circumstances and

a range of variables. Silage additives will not salvage poor quality forage, but when the right

product is selected for the right purpose they may help make good silage even better.

Making good silage in clamps

  • Ensure the forage harvester is blowing all chopped material into the trailer
  • Set forage harvester chop length according to grass dry matter content
  • Sheet the clamp side walls
  • Consider using a ‘clingfilm’ as a second top sheet to reduce oxygen ingress
  • Ensure all machinery entering the silage pit have clean wheels
  • Fill the clamp quickly in thin layers whilst ensuring sufficient compaction
  • Sheet down quickly after finishing
  • Weigh down the top sheet sufficiently

Multi-cut grass silage

Cutting grass earlier in the season and at shorter intervals will mean it is closer to optimum D-value at the point of ensiling and should therefore result in a higher feed value forage. It is estimated that this could amount to as much as an extra 1MJ/kg of energy in many cases – so 12MJ/kg ME silage instead of 11ME – which sets the platform for increasing milk production from forage.

Germinal’s guide to multi-cut silage making is designed to ensure maximum benefits are gained from this more progressive approach.

GUIDE TO MULTI-CUT SILAGE MAKING

Plan ahead

  • Consult your contractor or review your own equipment
  • Consider clamp capacity and/or bale storage area
  • Set targets for timing, tonnage and quality
  • Test soils and slurry over the winter period

Reseed to maintain leys fit for purpose

  • Maintain high sown species content and ground cover
  • Grow mixtures with high yielding varieties, good spring growth and high ME yield/ha
  • Only select varieties from Recommended Grass & Clover List (RGCL)

Over-winter swards with optimum cover

  • Remove autumn grazing stock by end of December with sward height at 4-5cm
  • Walk silage fields to check drainage, mole damage and weed content
  • Apply slurry into the soil, not onto the sward, to a maximum of 25,000l/ha

Ensure correct crop nutrition

  • Avoid heavy slurry applications within 10 weeks of cutting
  • Apply any slurry into the soil immediately fields are cleared
  • Apply bagged fertiliser as recommended by an agronomist but not exceeding 2 units/acre for each growing day between cuts

Cut early and frequently

  • Take first cuts late April – early May (depending on season and location) to maximise ME yield
  • Take subsequent cuts at intervals of 4 to 5 weeks to maintain quality
  • Mow no lower than 6.5cm to ensure rapid regrowth

Wilt quickly for optimum dry matter

  • Cut early in the day with a mower with an effective integral conditioner
  • Ted out the crop within two hours to maximise speed of drying
  • Aim to pick up the same day for a target 28 – 32% DM silage

Apply a proven silage additive to improve fermentation

  • Because protein and nitrates may be higher – which buffer the fermentation
  • Select an additive containing the most efficient fermentation bacteria

Chop long to maintain structural fibre

  • Consider a chop length of 5cm or longer for good clamp management
  • The typical chop length of a forage wagon can work well with multi-cut

Ensile for the best possible fermentation

  • Apply best practice approach when clamping or baling
  • Ensile in layers to maximise compaction
  • Roll or compact to squeeze out air
  • Seal effectively to maintain airtight conditions

Feed fibre as needed to balance rations

  • Ensure sufficient ‘scratch factor’ for optimum rumen function
  • Consult your nutritionist to maximise the value of higher energy silage

Understanding a silage analysis

Whether clamped or baled, conserved forage will often make up a large proportion of ruminant diets. It is important, therefore, to understand the nutritional value through a representative silage analysis.

* For well fermented silage lactic acid as the proportion as the total acids should be >75%.

 ** Different analytical companies use different units for expressing the values. This example shows g/kg DM to convert to % divide the value by 10.

GREEN

Indications of in-field crop quality –mD-value, ME, Crude Protein, ADF, NDF

RED

Indications of fermentation quality – Lactic Acid, Acetic Acid, Butyric Acid, Ammonia N, VFAs 

BLUE

Indications of both crop and fermentation quality - Dry Matter, pH, WSC

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