
Starts with the soil - Soil analysis

Nutrient management planning
Silage Quality
1. Fermentation (pH & Ammonia N)
2. Feeding value (D-Value, CP & Dry
Matter)

Silage Quantity
1. Tonnage required


D-value depends on stage of growth
and timing of harvesting
Very high D-value
High D-value
Moderate D-value
Low D-value
>75
>70
65-70
<65
Seed head not visible but
moving up the shoot
Seed heads fully
emerged and
elongated
Grass at 67 D-value
60 D Very stemmy with a dead base
12
Relationship between silage yield
and D-value
D-value
80
Total
DM yield
10
8
DM yield
of
digestible
material
6
67% D
70
4
65
2
0
24-Apr
4-May
14-May
24-May
3-Jun
Date
13-Jun
23-Jun
3-Jul
60
13-Jul
D-value
Yield (t DM /ha)
75
Why?


To assess feed value, predicted
animal performance and the need
for supplementation
To identify early the stability of the
silage and possible impacts on
waste and animal health
How?


Wait until 6 weeks post harvest
Take several cores across clamp




pH of between 3.8 and 4.2 is desirable
In the field after mowing - Respiration occurs
breaking down sugars.
Plant proteins are also broken down.
In the silo during filling –sugars are converted
to lactic acid in the absence of air until a pH
of 3.8 – 4.2 is reached.


In silo – If pH above 4.2 then undesirable
bacteria grow converting sugars to butyric
acid and protein to ammonia resulting in
poor quality silage.
During feed-out – if pH is above 4.2 then
sugars in the presence of oxygen are
converted to CO2 & heat. Yeasts & moulds
also grow rapidly.
1.
Sward type – PRG is better
2.
Nitrogen Application
3.
Stage of growth
4.
Weather & Grass Dry Matter
5.
Silo filling & sealing technique

1.
2.
3.
4.
Ensure sugar content of grass is high
(greater than 2.5% fresh weight) by:
Harvesting swards with a high PRG
content.
Applying slurry & fertiliser at correct rate
& time.
Harvesting in bright sunny weather.
Carry out ensilability analysis.

Indicates the potential fermentation
quality by giving information on:
1.
2.
3.
4.
5.
Dry matter
Crude protein
Water soluble carbohydrates (sugars)
Nitrate
Buffering Capacity

Rule of thumb – allow a day for every 2 units
of Nitrogen to grow out of grass

Hence 3 bags 27%N = 81 units

81 divided by 2 units/day

41 days required between fertiliser
application and cutting
Ensure silage dry matter is high by:
1.
2.
assessing % DM before harvesting.
harvesting grass at and/or wilting to
25 -30% DM.

Spread the herbage over as large an area as
possible immediately post mowing

Max wilting period 24-30 hours

Prolonged wilting reduces digestibility

Wilting results in increased silage DM intakes


1.
Can be used as an aid to make good silage
but not a remedy for poor management
Inoculants are the main type
Inoculants contain one or more lactic acid
bacteria and promote efficient fermentation
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
(6 – 9 inches)

Roll continuously

Rapid filling is best



All silage effluent must be collected.
The tank must be checked regularly to
ensure that it does not overflow or that it is
not leaking.
Empty the tank regularly to prevent
effluent reaching drains or watercourses




Same principles apply as with pit
silage
Bales should be dense and
cylindrical in shape
Wrap as soon as possible after
baling
4 - 6 layers of plastic film




Wrap at the stacking area if possible
If not, move bales from the field immediately
after wrapping
Oxygen will enter a bale every time it is
handled
Avoid spiking if possible at any time (even
before wrapping)
Example:
Width of pit = 10m
matter
Assume silage is 30% Dry
Section A:
30 x 3 x 10 = 900m3
Plus
Section B:
5 x 3 x 10 = 150m3 X 0.5 = 75 m3
Total = 900 + 75 = 975m3
3
m
A
B
30m
5m
Conversion Factors
Silage Dry Matter Conversion factor
Measuring Quantity
Silo/Pit:
Length (m) x Width (m) x Height
(m)
=
Volume (m3)
X
Dry Matter Conversion factor
=
Tonnes of silage
Measuring Quantity
kg/bale or t/bale
Round (unchopped) 1.3m
500
0.5
Round (chopped) 1.3m
650
0.65
Square (2.5mx1.2mx0.9m)
730
0.73
(8x4x3’)
Will vary enormously with dry matter, sward type and
operator!
Requirement
Silage
Silage
Requirements
Type of stock No
Months
per month (t)
requirement
Spring calver
1.0
250 – 350 kg
store
0.8
Calves
0.3
Ewes
0.15
Total silage required

Cut silage around 50% ear emergence to
optimise yield and quality

Allow 2 units N/day from sowing to cutting

Don’t overwilt – 30 hours max

Seal silo carefully

Handle bales carefully

Do a budget before winter
The amount of grass grown depends on many
factors
1. Soil temperature (>6° C)
2. Light
3. Water
4. Nutrient availability
5. Grass type/breed

At peak growth there is a new leaf
every 4-5 days (May)
 Peak growth all 3 leaves replaced in
2-3 weeks
 Best time to graze is at 2 ½ to 3
leaves


4 main grazing systems used
1.
Set stocking
2.
Rotational grazing
3.
Strip grazing
4.
Paddock grazing
Set stocking
Rotational
Paddock
grazing
Animals have unrestricted access over a wide
area throughout the grazing season
Pros
Cons
Low management input
Lower grass yield
Low capital cost (1 drinking
trough, external fence)
Difficult to manage and
maintain grass quality and
height
Can work well if sward height
maintained at correct level
Uneven manure distribution
Lower utilisation due to
trampling
Weeds allowed to build up
Animals move around a small number of fields based
on sward height or after a certain number of days
Pros
Cons
Higher production than
set stocking
More fencing required
Allows pasture to rest
and recover
Can extend the grazing
season
More even distribution of
manure
Extra drinking troughs
needed
Grass production and
utilisation not optimum
Animals given a new allocation of grass each day by
mean of electric fence
Pros
Cons
Useful when excess of grass at
points in the year
Labour intensive. Fence needs
moved each day
Good utilisation of grass – very
little trampling or spoiling of
grass
Water availability a problem
Very good for forage crops like
kale and rape
Not ideal as cattle are usually
allowed back over previous days
grazings
Hampers re-growth
Can lead to trampling along fence
line
Animals are moved frequently through a series of paddocks
based on measured grass heights or grass covers
Pros
Cons
Highest grass production and
use
Initial cost of fencing and
water troughs
High quality grass & higher
stocking rates
More intensive management –
skill required
More even manure distribution Requires careful monitoring
Can extend grazing season
Allows for excess grass to be
cut out as silage (bales)
Quieter/more manageable
stock?
System
Set
stocking
Annual
Utilisation
Usable
% increase
Yield
yield
(t DM/ha)
(%)
(t DM/ha)
8.5
50
4.3
Rotational
10.2
65
6.6
56%
Paddock
10.2
80
8.2
92%
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To be continued!