Silage Production

Silage for the High Forage Herd at Greenmount is made using a 24 hour rapid wilt system with targets of dry matter 25-30 percent; ME 11.5-12.0 MJ/KG DM and intake potential 85-90.

The key factors to consider to achieve this are:-

Sward Type
Fertilizer and Slurry Policy
Cutting Date
Ensiling Technique

Using earlier grass varieties cutting on the second week of May should give optimum performance.

Sward Type

High yields of quality silage start with the sward itself. To maximise the output of silage swards regular reseeding is important to achieve the increased potential of new varieties coming forward from the breeders. Management of these swards is critical to ensure as long a life as possible, however some general principles to adhere to when reseeding for quality early silage would be:

Keep the mixture simple. Use two or three compatible varieties.
Use about one third tetraploid, two thirds diploid perennial ryegrass.
Use early and mid season varieties.
Where management allows early grazing and short cutting intervals introduce new hybrid varieties.

In recent years farmers have moved too much towards mid and late varieties which have tended to produce lower first cut yields and run to stem and head quickly for second cut. Early and mid season varieties will produce much higher yields of quality first cut silage for higher potential milk output.

Fertiliser and Slurry Policy

Nitrogen is the key element influencing the yield of grass for silage. Experience has shown that optimum levels for first cut are around 120 KG N/ha with 100 KG N/ha for second and 80 KG N/ha for later cuts. It is crucial to ensure a proper balance of phosphate and especially potash which is limiting on many farms. Grass is only of value if it can be converted into milk at least cost. Similarly the various nutrients supplied to grow the grass crop are valuable only if they contribute significantly to yield.

To successfully grow a high yielding quality silage crop the requirement for potash is greater than for phosphate. Cattle slurry with its higher K2O : P2O5 ratio is well suited to help maintain the correct balance if properly used.

Early fertiliser application is important for optimum yield and quality

Timing is Everything

Analyse soil November/December
Apply slurry late January/early February
Apply fertiliser split dressings early and late March
Cut second week May
Apply fertiliser immediately after cutting.

Nutrient balance for first cut silage

	Soil Index P₂0₅ (3) K₂0(1)
	N	P₂0₅	K₂O
Grass nutrient requirement (KG/ha)	120	30	100
Plant food in 2300 gallon slurry/acre (KG/ha)	20	14	72
Balance from fertiliser (KG/ha)	100	16	28

Early Application of slurry and fertiliser allows harvesting at high D values with confidence of minimal contamination.

Cutting Date

The most important single factor influencing the quality of silage and the efficiency of converting grass into milk during the winter is the digestibility of the grass ensiled. This in turn is determined by the stage of growth at which the grass is cut.

Research indicates that with each week’s delay in cutting after the start of May, digestibility declines by approximately 1.8 units, with the same concentrate input this would result in a milk yield reduction of 0.6 litres/cow/day. To maintain milk yield would require an extra 1.2 KG concentrates/cow/day or over £1500 for a 50 cow herd.

Target Cutting Dates

1st cut Second week May

2nd cut Mid June

3rd cut End July

Fertilise the aftermath to build up a wedge for autumn grazing and allow increased rotation length.

The influence of cutting date on silage performance can be clearly seen from the following Milk Chek Table

Effect of cutting date

Week Number	May 1	May 2	May 3	May 4	June 1
% of farmers cutting Milk Yield (l/cow) Milk from forage (l/cow) MOFF (£/cow) MOFF (pence/litre)	4 5821 3821 1009 17.38	6 6373 4088 1124 17.62	34 6232 3867 1061 17.05	40 5763 3559 980 16.99	15 5649 3466 932 16.50

These recent results highlight that those farmers cutting on the second week of May achieved improved milk yield per cow and milk from forage with better margins per cow and per litre.

Ensiling Techniques

For the high forage system high intake silage is essential. One of the principle factors influencing the intake potential of a silage is its fermentation pattern. Silage fermentation results from the action of bacteria on sugars in the grass, which are converted to lactic acid. The most important factor in achieving a good fermentation in silage is attention to detail during silage making and filling. This involves:-

Cutting at 2"-3" above soil level.
Ensiling cleanly and quickly
Ensuring machinery is properly set to avoid soil contamination.
Using an inoculant to enhance the fermentation process.
Covering the silo each night to exclude as much air as possible.
Consolidating during filling and sealing the silo immediately with a new sheet, covered with one or two old sheets, all weighted down to minimise top waste.

Table Milk yields sustained by different quality silages offered as the sole feed and with 8 KG concentrate/cow/day

	Poor quality silage Intake value = 55 ME = 9.5 MJ/kg DM	Average quality silage Intake value = 70 ME = 10.5 MJ/kg DM	High quality silage Intake value = 85 ME = 11.5 MJ/kg DM
Silage only	1	7	15
Silage + 8 KG concentrate	19	25	31
Value of milk at 20p/litre (p)	20	140	300

Source : Hillsborough Feeding Information System

The table illustrates the economic importance of high quality silage.

Rapid Wilting

High performance silage will have a dry matter of around 30 percent. It is important to achieve this in less than 24 hours to minimise field losses. Grass will have to be spread in slow drying conditions to achieve this. Working closely with a good contractor can help to reduce the overall cost of silage making. More and more farmers are now using a contractor to help reduce their total fixed costs and allow them more time to manage their grass and their cows.

Free access to fresh silage daily is essential for high intakes

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