How to Get Started with Multi-Cut Silage
12 June 2024Thanks for subscribing! Please check your email for further instructions.
System overview
With the increasing cost of purchased concentrates and forages putting pressure on margins, farmers are looking to get more production out of their home-grown forage. A multi cut silage system involves cutting earlier and more often with around 4-6 cuts annually, harvested at around 28–30-day intervals. This is perceived by some farmers as a more expensive way of producing forage largely due to the higher harvesting costs, but these costs will be far outweighed by:
- increased milk production.
- reduced concentrate usage.
- higher quality forage.
A multi cut silage system leads to increased metabolisable energy and protein levels with higher dry matter yields over the course of the season.
Benefits of a multi-cut system
One of the main benefits and reasons for switching to a multi cut system is the improved forage quality in terms of higher energy values, greater intake characteristics, higher digestibility and less dead material ensiled leading to a greater amount of milk being produced from forage.
Greater overall yields are achieved as the grass is cut when it is at its leafy stage which promotes rapid regrowth and reduces the amount of ‘recovery time’ between cuts.
Grass yields, per cut, will be lower which will help shorten drying times, leading to reduced nutritional losses during wilting.
Less bulky crops will mean less wear and tear on machinery and reduced fuel usage per cut. The harvesting process is also a lot quicker which not only helps during ‘catchy’ weather windows but also means the silage clamp is open for a shorter period during ensiling.
| Parameter | 3 cuts | 5 cuts | Results |
|---|---|---|---|
| Average tonnes DM/ha | 16 | 16.92 | 0.92 |
| Average ME (MJ) | 10.9 | 11.4 | 0.5 |
| Energy Yield (ME/Ha) | 175,239 | 193,821 | 18,582 |
| Average D-Value (%) | 69.7 | 72.7 | 3 |
| Crude Protein (%) | 13.9 | 16.7 | 2.8 |
| Milk Yield /ha (based on ME) * | 33,064 | 36,570 | 3506 |
* 5.3 MJ of ME produces 1 litre of milk
Source: Volac UK
Based on the above figures and an average milk price of 37ppl this would equate to £1297/ha of extra revenue under the multi cut system.
When the extra contracting costs of £584/ha (2 extra cuts using contractors for fertiliser, slurry application, mowing, tedding, raking, chopping, clamping. NAAC 2023) are considered it leaves a margin of £713/ha.
Timing your cut
Swards for a multi cut system need adequate winter rest with first cut taken in the last week of April/early May before grass covers get too long and grass quality starts to deteriorate. Multi cut silage applies the same principles as rotational grazing, with grass cut at peak growth before leaves begin to die off and enough residual grass left to optimise photosynthesis and recover quickly before the next cut. The optimum time for harvesting is when the grass has a NDF value of 40 and a D-Value of 75. This would aim to produce a silage with an ME of 12MJ/Kg/DM, comparable with that of grazed grass. For every day that cutting is delayed, the digestibility of the grass falls by 0.5%/day – this dictates the metabolizable energy (ME) of the grass.
Harvesting methods
Setting the mower to cut no lower than 6.5cm will ensure a suitable residual which encourages rapid regrowth. Cutting slightly higher also helps to keep the grass off the floor to promote quicker drying and prevent soil contamination.
As the grass is a lot leafier it will have a higher oil content care so needs to be taken regarding chop length to avoid clamp slippage. The table below indicates the ideal chop length for differing DM % of grass.
Table 2. Recommended chop length according to silage dry matter.
| Dry matter of silage (%) | Recommended chop length (cm) |
|---|---|
| Over 37 | 1-Feb |
| 32 - 37 | 2.5 |
| 28 - 32 | 2.5 - 5 |
| 22 - 28 | 8 |
| Below 22 | 8-Oct |
Source: Dr David Davies, Silage Solutions Ltd.
Tedding may be required if weather conditions are less than ideal to promote faster drying with the aim of picking the grass up 24 hours after cutting.
Forage wagons
As farms have continued to expand and with bigger acreages to cover self-propelled foragers are the preferred choice by many contractors and larger milk producers. However, with the increases in fuel prices over the years, labour supply, price of machinery and a greater uptake of the multi cut system, there has been a resurgence in the use of forage wagons as a means of harvesting the grass. The suitability of this type of harvest system largely depends on the topography of the farm and availability of equipment. Another alternative to the high costs involved with self-propelled machines is the trailed precision forage harvester where outputs of 40-48ha/day can easily be achieved.
Some modern self-propelled forage harvesters that measure yield and other constituents as the grass is picked up can simultaneously alter the chop length as the dry matter changes. Overall multi cut silage can be harder to consolidate due to the greater proportion of leafier material within it which has less structural fibre.
Consider using additives
The use of an additive is strongly recommended. With higher protein levels in the grass, buffering can be higher and cause difficulties in achieving a lower pH for effective preservation. Sugar levels may also be lower with earlier cutting as sugar accumulates as the plant grows. Grasses with low sugar content produce less lactic acid during the fermentation by the naturally occurring bacteria on the grass. An appropriate additive will ensure that the sugars are used more efficiently.
Nutrient applications
With a multi cut system nutrient applications need to be planned more carefully to ensure optimum use and promote grass growth without compromising fermentation of the ensiled grass. Nutrient applications should be flexible to balance maximising yield and producing a quality forage which will ferment when ensiled. High levels of N produce grass with low sugar levels and silage containing high levels of ammonia and butyric acid can affect palatability. To calculate nutrient applications prior to each cut always work backwards from your target cutting date. In ideal growing conditions grass can utilise 2.5Kg/N/day (around 2 units of N/acre/day). It is prudent to aim for all the N to be utilised at least 7 days before cutting, allowing for periods of slower uptake due to weather conditions. For a cutting interval of 28–32-day swards will only require 58Kg N /ha (46 units/acre) to ensure all the nitrogen is utilised. The target yields, previous cropping, soil type and rainfall should all be considered when deciding what nitrogen application rates are suitable for your swards. Laboratory sampling of the fresh grass can help assess whether the nitrogen content of the grass is suitable for cutting. Soil health and nutrient status should be monitored closely to ensure soils are at a pH 6.2-6.5 and P and K levels are maintained at a moderate plus status.
Grass species choice
Intermediate and late heading varieties, from the recommended list, are best suited to a multi cut system as they provide early season growth as well as persistency to maintain yield and quality later in the season. A mix of diploid and tetraploid varieties along with some high sugar varieties will ensure good intakes along with higher D value forage quality. To capitalise on the benefits of a multi cut system, higher yielding modern grass varieties should be grown. Red or white clover should be considered for inclusion in the grass mix to increase the crude protein and trace elements levels within the silage and to provide crop benefits through nitrogen fixation.
Changes to your costs
While a multi-cut system will reduce your costs elsewhere, increased harvesting costs can pose a major barrier to changing to a multi cut system, particularly if using a contractor. Traditionally mowing, tedding, raking and most of the time, foraging, is charged by the acre so it can work out quite expensive. As multi cutting tends to be a quicker process, paying by the hour for the forage harvester would be a better option. Due to the frequency of cutting it is essential you have a good relationship with your contractor, and they are aware of what you are trying to achieve to ensure grass cuts are taken at the appropriate time to capitalise on producing a quality forage.
Technical points to consider
- Plan nutrient applications carefully to avoid excessive nitrogen levels in the grass when you want to cut. Always factor in the nitrogen applied in organic manures.
- Talk to your contractor to let them know of your plans or if you do your own silage making ensure machines are serviced and ready to go.
- Ensure silage clamps are cleaned out, so you are prepared to take advantage of the perfect weather window.
- Ensure tedders and rakes are set up correctly to not only avoid soil contamination but also prevent leaf shatter which results in higher nutrient losses.
- Tailor chop length to DM % to avoid slippage in the clamp.
- Apply slurry and any artificial fertiliser as soon as possible after grass removal to encourage grass regrowth.
- Additional fibre sources may be needed in the diet, particularly dry cows to maintain rumen health and function. Consider using older swards or leaving silage to mature to make a dry cow silage.
When it comes to creating diets for livestock, ensure the benefits in improving forage quality through a multi cut system are reflected by either reducing concentrate feed and maintaining milk yield, or by increasing milk yield due to the higher quality forage base.
For more information, please visit www.fas.scot or contact the advice line by emailing advice@fas.scot or calling 0300 323 0161.
David Darlington, SAC Consulting
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