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.Water4.Nutrient availability5.Grass type/breed

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

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

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

Not easy to achieve high utilisation

1.Poor sward composition (old grasses, weeds)

2.Previous grazing history

3.Dung and urine areas

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 ConsLow 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 ConsHigher production than set stocking

More fencing required

Allows pasture to rest and recover

Extra drinking troughs needed

Can extend the grazing season

Grass production and utilisation not optimum

More even distribution of manure

Animals given a new allocation of grass each day by mean of electric fence

Pros ConsUseful 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 ConsHighest 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 Annual Yield

(t DM/ha)

Utilisation

(%)

Usable yield

(t DM/ha)

% increase

Set stocking

8.5 50 4.3  

Rotational

10.2 65 6.6 56%

Paddock 10.2 80 8.2 92%

Grass is usually measured in kg of Dry Matter

Grass availability measured in kg DM/ha

Lowland ground has the potential to produce 12 tonnes DM per hectare per year

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

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!

Number of methods used

1.Sward assessment using rising plate meter

2.Visual assessment

3.Sward heights

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

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/ha4-5 cm

2000 kgDM/ha6-8 cm

2500 kgDM/ha8-12 cm

3000 kgDM/ha>12 cm

Pre-grazing cover of 3000kgDM/ha (12cm)

Exit paddocks at 1600kg DM/ha (4cm)

Available grass is therefore 1400kgDM/ha

If paddock is above 3500kgDM/ha then consider taking out for silage

Class of stock

Grazing period

Rotational grazing Set Stocking (cm)

Pre-graze (cm)

Post-graze (cm)

Cows and calves

Apr/May 10 - 14 4 5 - 6

June/July 12 - 15 4 7 - 9

Aug-Nov 12 - 15 5 7 - 9

Growing or finishing

Apr/May 10 - 12 4 5 – 6

June/July 10 - 14 4 6 – 7

Aug-Nov 10 - 15 5 7 - 8

After weaningFat ewes – 1650 kgDM/ha (3cm)Thin ewes – 2450 kgDM/ha (6cm)

Tupping1800kg DM/ha (5cm)

Mid-Pregnancy Graze down to 1500kg DM/ha (3cm)

Lambing outsideOnto 1800kg DM/ha (6cm) 4-6 weeks pre-

lambing

Stage Cover kg DM/ha

Sward height (cm)

After weaning Fat ewesThin ewes

16502450

36

Tupping 1800 5

Mid-Pregnancy Graze down to 1500

3

Lambing outside

Move onto 1800 4-6 weeks pre-lambing

6

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 per ha

March April-June July-August

September-October

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

Considerable research evidence which indicates benefits of early turn out

Could include grazing some of area to be harvested for silage up to start April

Later turnout leads to high grass covers being grazed and utilisation is lowered

Animal performance over grazing season suffers if cattle turned out later

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 per ha

March April-June July-August

September-October

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

Options

1.Apply nitrogen

2.Introduce supplementary feeding

3.Sell stock or cull unproductive animals

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

Options

1.Pre-mowing or topping

2.Higher stocking rate

3.More measurement & management