Level II Agricultural
Business Operations
Good quality silage is a key factor in
profitable milk production

Silage Production

Silage Assessment

Dry Matter (DM)

Metabolisable Energy (ME)

Crude Protein (CP)

Fermentation (acidity level pH and
ammonia level NH3)

Dry Matter is the feed remaining after all the
water has been taken out

Dependent on weather and degree of wilting

Ideally 25-30%

Grass wilted over 30 % is more difficult to
consolidate

More prone to spoilage by yeasts and moulds
ME measures the energy content of silage
in MJ/kg DM
Very high
High
Moderate
Low
>12
11.5 – 11.9
10.5 – 11.4
<10.5
CP measures the protein content of silage
as a percentage of DM
Very high
High
Moderate
Low
14%
12 –14%
10 –12%
<10%

pH of between 3.8 and 4.2

Ammonia (% of total Nitrogen) less than 10
is desirable

Good fermentation is needed to ensure the
stable conversion of ensiled grass to silage

Poor fermentation produces silage
unpalatable to stock
1.
Sward type
2.
Nitrogen application
3.
Stage of growth
4.
Weather & grass DM
5.
Chop length
6.
Additives
7.
Silo filling & sealing technique

Perennial Ryegrass swards will produce better
quality and higher D-value silage than old swards

Heading date of grasses in sward will have effect
on quality and D-value (early/intermediate/late)

Newly reseeded swards generally produce higher
quality silage

Rule of thumb – allow a day for every 1kg/day
(2 units) of N to grow out of grass

Allow for both slurry and fertiliser N

Grass analysis indicates the potential
ensilability and fermentation of crop



Yield increases rapidly from mid April to
late June
Quality decreases rapidly from mid May to
mid June
The stage of growth at which crop is cut will
have more influence on feeding value of
silage than any other factor under the
farmers control
3. Stage of Growth
High ME Silage
3. Stage of Growth
Low ME Silage

High DM silage is weather dependent

Aim to harvest at 25 – 30 % DM

Rapid wilting preferable (24-30 hours)

Reduces effluent

High DM (>30% DM) is better chopped short –
approx 25mm (1 inch) – allows for better
consolidation

Lower DM (<25% DM) is better with longer
chop length – 50 mm (2 inches) or above

Aid to make good silage

Inoculants are the main type
◦ Inoculants contain one or more lactic acid
bacteria and promote efficient fermentation

Acid additives no longer commonly used
Grass placed on top
by hand
50mm drainage pipe
0.125mm polythene
125 mm
600
mm

Clean pit thoroughly

Hang plastic side sheet to ensure good seal

Spread grass over pit evenly in shallow layers
150 – 225 mm (6 – 9 inches)

Roll continuously

Rapid filling is best

Silage effluent is highly pollutant and must
be collected

If stored with cattle slurry, extreme care
must be taken when mixing due to
increased risk of gaseous emissions

Tanks must be checked regularly to prevent
overflow and leakage

Same principles apply as with pit silage

Bales should be dense and compact

Wrap as soon as possible after baling

4 - 6 layers of plastic film

Wrap at the stacking area if possible

Avoid excessive handling

Store bales immediately after wrapping

Storage in line with NIEA regulations
◦ Effluent must be collected from bales stored
on concrete etc.

Protect against vermin damage

Calculating available silage is the first
step in winter feed planning
◦ Assess silage in store
◦ Assess silage required
◦ Carry out a balance
1.
Silo length
2.
Silo width
3.
Average silo height
4.
Calculate volume
(length x width x height)
10.6 m
3.3 m
Volume = 10.6 X 3.3 X 22.8
22.8m
798 cubic metres (@ 20%DM)
Silage Dry Matter
Grass silage
Silage Density
Multiply volume by
18%
0.81
20%
0.77
25%
0.68
30%
0.60
10.6 m
3.3 m
Volume = 10.6 X 3.3 X 22.8
798 cubic metres
798 X 0.77 = 614 t
22.8m
Pit
1st
Length
22.8
Width
10.6
2nd
18.9
9.1
Height Volume Factor
3.3
0.77
798
2.1
0.77
361
Tonne
614
Total
892
278
Animal
Silage
No.
required
(t/cow/mth)
No
mths
Total (t)
Milk cow
Dry cow
60
20
1.5
1.2
6
6
540
144
In Calf
Maiden
10
1.2
1
6
6
72
Total
required (t)
756
Assess silage available against silage
required
Available silage = 892 tonnes
 Required silage = 756 tonnes

In this example 136 t of silage is
surplus to requirement

Aim to make high quality silage

Ensure correct fertiliser application

Consider grass analysis pre-cutting

Choose suitable cutting stage and weather

Consider rapid wilt

Collect and handle effluent safely

Calculate quantity of silage