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!