Managing Pastures for
Longevity with Grazing
Gene Pirelli
Mylen Bohle
What is Grazing?
• Grazing is the meeting of cow and
grass…….Andre Voisin
Overgrazing
• A locomotive meeting a Ford
Pinto
Overgrazing
• Results in severe defoliation of pasture
plants.
• Continuous overgrazing does not allow
plant to recover.
• Plants eventually die when a stress period
is encountered.
Average
Forage
Height is
2.5 Inches
Total Dry
Matter is
1000
pounds per
acre…
Overgrazed?
YES!
Grazing Problems Can Be
Avoided
• By Managing Plants.
• By Managing Livestock.
Principles of Plant
Physiology
• The three stages are: an early period
of slow growth, a central period of
rapid growth and a final period of
slow growth.
• Grass growth is a sigmoid
curve….Voisin
Grass Productivity
• Andre Voisin was a French scientist
who spent hours observing the
grazing behavior of livestock in the
early 20th century.
• He came up with some principles of
plant management and grazing that
are even more valid today
Several Voisin Principles
• Your main objective is to grow
forage. Animals are a tool to harvest
forage.
• Plants, in order to survive, need
REST and animals should be rotated
through paddocks. He called this
“ration grazing.”
Several Voisin Principles
• There are stages that are proper to
graze and stages that are harmful to
the plant.
• The total occupation period in a
paddock should be short so that
grass sheared on the first day is not
sheared again.
New Zealanders use a similar
system to explain growth based
on phases
• Phase 1
• Phase 2
• Phase 3
Plant Growth Phases
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
1.
5
3 4.
5
6 7.
5
9 10
.5
12 13
.5
15 16
.5
Phase One
• Plant growth is less than 3
inches high.
• This period is called a lag
phase.
Total Dry
Matter is
1000
pounds
per acre
Three inches and below…
• The plant stores sugars and
carbohydrates in this area.
• This part of belongs to the plant
and is critical for long term
survival.
Phase Two
• Plant growth is 3 - 10 inches
high.
• This period is called a
vegetative growth phase.
Total
Dry
Matter
is 2500
pounds
per acre
Phase Three
• Plant growth is over 10 inches
high.
• Plants are moving towards
maturity and reproduction.
• No net increase in DM.
Grazing at this stage
can result in
wasting up to 60%
of the forage
Protecting the Pasture and
Growing Feed
• Let’s look at some strategies
to protect the plant
The Goal…..
• Is to keep the pasture in phase II all
year round.
Why Phase II?
• Preserves energy reserves in the
plant and roots. Provides for plant
health.
• Higher nutrient content of forage for
grazing. Translates into higher milk
production or ADG.
Crude
Protein is
27.7
Percent
Acid
Detergent
Fiber is
21.7
Nutrient Requirements for
Producing Ewes
Production
Stage
WEIGHT Crude
Protein (lb)
TDN (Lb)
Dry 176 Lbs .27 1.6
Last 4 wks
gestation
176 + Lbs .44 2.4
First 6 wks
lactation
176 - Lbs .96 4.3
Nutrient Requirements for Beef
Steers
WEIGHT
Daily
Gain
Crude
Protein
(Lbs)
Crude
Protein
(%)
TDN
(%)
400 Lbs 2.0 Lbs 1.48 13.1 63
600 Lbs 2.0 Lbs 1.67 10.9 63
Nutrient Requirements for Feeder
Lambs
WEIGHT
Daily
Gain
Crude
Protein
(Lbs)
Crude
Protein
(%)
TDN
(%)
65 Lbs .75 Lbs .41 14.5 63
110 Lbs 1.0 Lbs .35 10.0 77
What “tools” do
grazing managers use
to control defoliation?
Grazing systems Integrate the components of animal, plant, soil,
environment, and management in site-specific
applications of principles that work globally.
Performance of the system is influenced by all
the parts.
Matching seasonal forage growth with livestock
needs is one of the major challenges.
Grazing system considerations Systems should be:
• Easy to manage
• Be flexible to accommodate changes
• Maximize grazing days
• Minimize need for stored feed and
supplements
• Recycle nutrients
• Be practical and profitable
Grazing methods Two primary methods:
• Continuous stocking
• Rotational stocking – Management Intensive
Grazing methods are designed to achieve specific objectives.
Several different methods are often used with a grazing system.
Continuous
• Animals have access to the entire
grazing area during the grazing
season.
• Difficult to control the defoliation
rate and pattern.
Management Intensive Grazing
• Also known as Rotational or
Controlled Grazing.
• Requires more “management time”
than continuous grazing.
Management Intensive Grazing
• Allows the livestock owner to
control the grazing pattern of
the animals.
Management Intensive Grazing
• Controlling the grazing
pattern is the way to keep the
plants in Phase Two.
The Number of Paddocks or
Cells can Vary
• More subdivisions means that the
livestock must be moved more
frequently.
Other Types of Grazing
• Strip Grazing
• Creep Grazing
• Mixed Species
Strip Grazing
• Animals are allowed access to strips
of the pasture.
• Allows the pasture to be “rationed.”
• Animals have access to the
previously grazed area.
Creep Grazing
• Younger animals (calves or lambs) are
allowed to graze ahead of the herd or
flock.
• They have access to higher quality feed.
Mixed grazing Combines two or more animal species in
the same grazing system:
• May graze together or separately
• Takes advantage of differing preferences for
forage species, canopy heights, and chemical
composition
Cow-sow mixed grazing. Sheep-goats mixed grazing.
To Be Successful
• Grazing managers must use the type
of grazing system that fits their
ranch.
• Grazing managers must be aware of
defoliation and residual dry matter.
Designing systems • Begin with things that can’t be changed
landscape and climate
• Determine what forages are best suited cool/warm season and species
• Match feed requirements and supply
• Identify how forage deficits will be filled
Designing systems • System types
• Regional differences
Fencing considerations Different types, differ widely in cost and
maintenance requirements:
• High tensile wire (electrified or not)
• Barbed wire
• Electrified tape or wire
• Woven wire
• Board
• Stone
Best choice depends on economics, availability, durability
requirements, and safety requirements.
Livestock water considerations An adequate supply of good quality water is
essential to maintain animal health:
• Green succulent forage reduces water needs
• Water consumption increases as temperatures increase
900-lb lactating cow; 11.4 gallons 16.2 gallons when
temperatures increase from 41F to 90F
• Access to water; < 0.5 – 1.0 mile, steep to gentle terrain
• Water pollution issues are of concern
Measure Often
Move Stock
Timely
Ungrazed Grazed
Single Wire
What’s Next??
• A big sheet of paper or poster board
on a kitchen table!
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