Transcript CAFRE Development Service

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To gain an understanding of how and when
grass grows and is utilised
To understand different grazing systems
To learn how to budget grass and measure
grass covers
To gain understanding of how to plan grazing
and stocking rates for ranges of stock
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
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Perennial Ryegrass (most commonly
sown grass type in NI) has 3
individual leaves on each plant
 As the fourth leaf begins to grow, the
first and oldest leaf dies
 Hence new growth only replacing the
lost dead grass
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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
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No point growing grass if we can’t get
animals to use it properly!
Utilisation ranges from 50% to 80%+
Key is graze at right time, to the right
height and with right amount of stock
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Not easy to achieve high utilisation
1.
Poor sward composition (old grasses,
weeds)
2.
Previous grazing history
3.
Dung and urine areas
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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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Grass is usually measured in kg of Dry
Matter
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Grass availability measured in kg
DM/ha
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Lowland ground has the potential to
produce 12 tonnes DM per hectare per
year
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However, due to lower inputs and poor
grazing management typical utilisation
in NI is 5.0 tonnes DM/ha
Well managed farms 8-10 tonnes DM/ha
realistic target
Daily grass growth varies from 5kg
DM/ha in February to 100kg DM/ha in
May
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Grass cover is the average amount of
grass to ground level
This includes the grass available for
grazing and that which is left after
grazing
Important to know how much there is!
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Number of methods used
1.
Sward assessment using rising plate
meter
2.
Visual assessment
3.
Sward heights
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As rod is lowered
into pasture, plate
is supported by
height and density
of grass
This is averaged
out over a
paddock/field
taking number of
readings across
field
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Walk each field in
‘W’
Take 30-40 top leaf
readings
Avoid gateways etc
Calculate field
average and record
Keep record each
week
1500 kgDM/ha
4-5 cm
2000 kgDM/ha
6-8 cm
2500 kgDM/ha
8-12 cm
3000 kgDM/ha
>12 cm
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Pre-grazing cover of 3000kgDM/ha
(12cm)
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Exit paddocks at 1600kg DM/ha (4cm)
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Available grass is therefore
1400kgDM/ha
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If paddock is above 3500kgDM/ha then
consider taking out for silage
Class of
stock
Cows and
calves
Growing or
finishing
Grazing
period
Rotational grazing
Pre-graze
(cm)
Post-graze
(cm)
Apr/May
10 - 14
4
5-6
June/July
12 - 15
4
7-9
Aug-Nov
12 - 15
5
7-9
Apr/May
10 - 12
4
5–6
June/July
10 - 14
4
6–7
Aug-Nov
10 - 15
5
Set Stocking
(cm)
7-8
After weaning
Fat ewes – 1650 kgDM/ha (3cm)
Thin ewes – 2450 kgDM/ha (6cm)
Tupping
1800kg DM/ha (5cm)
Mid-Pregnancy
Graze down to 1500kg DM/ha (3cm)
Lambing outside
Onto 1800kg DM/ha (6cm) 4-6 weeks prelambing
Stage
Cover kg
DM/ha
Sward height
(cm)
1650
2450
3
6
Tupping
1800
5
Mid-Pregnancy
Graze down to
1500
3
Lambing
outside
Move onto
1800 4-6
weeks prelambing
6
After weaning
Fat ewes
Thin ewes
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Another method of grass budgeting
Examine fields or paddocks that a group of
stock are grazing and estimate how many
days it will be until they are back where they
just left
12 days is adequate in May – over 14 should
trigger considering taking out surplus
Lower than ten indicates a shortage
As move toward autumn grazing days ahead
must increase towards 30
Stock carried March
per ha
April-June
July-August
SeptemberOctober
Cow & calf
2
3.5
3
2
400kg store
2
5
3
2
320kg store
3
6
4
2
250kg store
4
8
5
3
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Considerable research evidence which
indicates benefits of early turn out
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Could include grazing some of area to be
harvested for silage up to start April
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Later turnout leads to high grass covers
being grazed and utilisation is lowered
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Animal performance over grazing season
suffers if cattle turned out later
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Preparation starts the previous autumn
Keep group size small
Don’t turn out all cattle
During wet weather subdivide grazing
paddocks and move cattle every 1-2
days
Be flexible – if too wet after 10 days,
bring cattle back in. 10 days feeding
saved
Stock carried March
per ha
April-June
July-August
SeptemberOctober
Cow & calf
2
3.5
3
2
400kg store
2
5
3
2
320kg store
3
6
4
2
250kg store
4
8
5
3
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Options
1.
Apply nitrogen
2.
Introduce supplementary feeding
3.
Sell stock or cull unproductive
animals
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Options
1.
Increase stocking rate
2.
Close up area for silage/Take area out
for round bales
3.
Reduce supplementary feeding
4.
Reduce fertiliser rate
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Options
1.
Pre-mowing or topping
2.
Higher stocking rate
3.
More measurement & management