Grazing Management
to Meet Animal
Performance Targets
Mark Kennedy
State Grazinglands Specialist
USDA-NRCS
Houston, MO
Meeting the Nutritional Needs
of Livestock from Pasture
INTAKE
INTAKE
INTAKE
Overview
 Balancing animal numbers and forage
supply
 Matching diet quantity and quality needs
 Matching grazing management and
paddock numbers
Animal Intake / Stocking
Rate
 There is only a certain amount of forage
produced in any plant community that is
available for use. Every acre can only
support a finite amount of animal weight
 Matching the type and number of
livestock to the forage base is very
important for meeting animal targets as
well as maintaining pasture condition
The 1st Step: Balance Livestock
Numbers with Forage Supply
•
Stocking rate: The number of animals or animal
liveweight assigned to a grazing unit on a seasonal basis.
•
Carrying capacity: The stocking rate that provides a
target level of performance while maintaining the integrity
of the resource base.
•
Stocking rate has a big effect on intake and availability.
Carrying capacity of pasture is
determined by four factors
Carrying
Capacity
Forage
Production
X
Seasonal
Utilization Rate
X
Length of the
Grazing Season
=
Daily
Intake
Carrying Capacity
 Example:




Stocker operation(buying 500# selling 800#)
200 day seasonal grazing (April 1 - Oct. 20)
16 paddock system (1-3 day grazing period)
8000 lb. total forage production (from
history/experience, soil survey, forage
suitability groups)
Grazier’s Arithmetic
Then ….
Carrying
8000 lb/acre X .65
=
Capacity .03 lb forage/lb liveweight X 200 days
= 867 lb liveweight / acre
Grazier’s Arithmetic
 867 lbs. per acre/500 lb = 1.73 steers/ac
 Can we stock 1.73 steers/ac initially?
 If we expect them to grow to 800 lb. then
 800 + 500 = 1300/2 = 650 (avg wt)
 867/650 = 1.33 steers/ac
Forage Intake on
Pasture
 Quantity/Availability
 Proper stocking rates, grazing management
 Quality
 Grazing management, species selection
Effect of Forage Availability
on Relative Forage Intake
Effect of Forage Availability
on Relative Forage Intake
How much does a 1,000 lb
Cow eat?
@2.5% BW about 25lb DM
With limited availability
19 lb DM
Intake
 75% Availability
 Time spent grazing
 6–10 hours per day
 6–10 hours ruminating
 Biting rate
 Cattle avg. 50
bites/min
 Bite size
 Cattle average 0.3 g
DM per bite
 Measured range of
0.07 to 0.59 g per bite
 Related to availability
 25% forage quality
Factors Affecting Intake
Dry matter intake =
Biting Rate x Biting (grazing) Time x Bite Size
Dry matter intake =
50 bites/min x 600 min/day x 0.3 g/bite =
9.0 kg or 19.8 lb DM intake per day
Factors Affecting Intake
If bite size is only 0.07 g/bite
50 bites/min x 600 min/day x 0.07 g/bite =
2.1 kg or 4.6 lb DM intake per day
If bite size is 0.59 g/bite
50 bites/min x 600 min/day x 0.59 g/bite =
17.7 kg or 38.9 lb DM intake per day
Effect of Forage Availability
on Relative Forage Intake
6 - 10”
2 - 3”
The Quantity – Quality
Compromise
Factors affecting forage quality

Plant maturity

Species
Plant
Part
Factors affecting forage quality

Plant maturity
 Growth
stage
 Length of rest period
Plant Growth Phases
Rest Period Needs
Clover
Annual Lespedeza
Orchardgrass
Stockpile
Birdsfoot Trefoil
30 - 35 days
20 - 25 days
Yield (tons/A)
1.0
Fescue
15 - 20 days
1.5
0.5
0.0
Spring
Summer
Fall
Factors affecting forage quality

Plant maturity

Species
Factors affecting forage quality

Species
 Legumes
> grasses
 Annuals > perennials
 Cool-season > warm season
Forage Chain
Winter
J F
Spring
M A M
Summer
J J A
Fall
S O N
Winter
D
LEGUME, Cool seanon grass – based
perennial pastures
Winter Annuals-rye,
ryegrass, triticale,
brassicas
High Quality
Hay/stockpiled
fescue
Summer
Annualsforage
sorghums,
sudangrass,
millet, corn,
crabgrass,
perennial warm
season
grasses
Winter Annuals – rye,
ryegrass,
triticale,brassicas
High Quality
Hay/stockpiled
fescue
Diversity is the Key
 Diverse pastures are
more productive
 Are less prone to
disease and insect
damage
 Broadens nutritional
opportunities of the
grazing livestock
 Legumes provide
nitrogen for the grass
and improve overall diet
quality
Factors affecting forage quality

Plant part

Leaves vs stems
 First bite vs second bite
3 Factors Affecting Forage Quality
1. Maturity
2. Species
3. Plant Part
1st bite: leaves with low fiber
High quality
2nd bite: medium quality
3rd bite: stems with high fiber – low
quality – leave for regrowth
Animal Requirements vs
Forage Quality at Different Maturities
• Can use different stages of quality to our
advantage
• Adjust body condition score
• Increase, maintain, or decrease body condition
• Creep grazing
• Calves allowed to creep gaze into higher quality pasture
• “Leader – Follower” grazing
• Animals with highest nutrient needs graze pasture first
followed by those with lower nutritional needs
High Quality -First grazers
Medium quality - Last grazers
Expected Intake of
Different Quality Forages
Intake as a
Forage
Relative Feed % of Body
Quality
Value
Weight
---------------- ---------------- ---------------Poor
<80
1%
Average
85-115
2%
Good
120-140
2.5%
Excellent
>150
>3%
Estimated Nutrient Content of
Tall Fescue at Different Maturities
NDF % ADF %
CP %
NEm
NEg
Mcal/lb Mcal/lb
Vegetative
49
27
20
0.70
0.39
Late boot
57
36
16
0.58
0.29
Mature
70
42
8
0.53
0.23
Animal Requirements vs
Forage Quality at Different Maturities
600 lb beef steer, 2.0 lb ADG
Intake Intake
% bw lb DM
Requirement
CP
lb
NEm
Mcal
ADG
lb/day
2.5
15.0
1.6
5.2
Vegetative
2.5
15.0
3.0
10.5
2.0+
Late boot
2.1
12.6
2.0
7.2
1.2
Mature
1.7
10.2
0.8
5.4
<0.5
Performance
Monitor your forage for
quality
Tried and true method
How high is the pile?
Forage Quality:
Pancake batter, Pumpkin
Pies or Wedding Cakes?
The Key to Successful
Grazing Management
 Flexibility
 The ability to
adapt or modify,
being
responsive to
changing
conditions
Grazing Management
Objectives
 Have grazing animals take 1 large bite or
mouthful (animal intake) off of as many plants
as possible in a pasture (Utilization)
 Remove the animals from the pasture before
any regrowth occurs and by the time 50% of
the current growth has been removed (plant
persistence/health)(animal intake)
 Have enough pastures to allow sufficient
regrowth and rest before being grazed again
(rest/plant health) (animal intake)
Mark Kennedy, Ozarkian, 2007
Plant Growth and Management:
During grazing periods: control stubble height
•not too low—keep growing points
•not too low—good photosynthesis for regrowth
•not too low—keep roots growing
•not too low – maintain bite size for intake
Between grazing periods: schedule rest periods
•allow photosynthesis
•allow leaves to regrow to proper heights
•not too long or forage quality declines
Plant Growth and Management:
•
Example: 12 paddock system
• Grazing period
2 day 3 day
• Rest Period
22 day 33 day
Flexibility!
4 day
44 day
Matching Forage and
Animal Resources
 Enterprises with higher potential net
return require higher quality pasture
and more intensive management




Greater forage yield per acre
Forage quality should be better
Management must be more intensive
Number of paddocks should be greater
Matching forage and livestock resources
 Economic potential of grazing enterprises

Pasture-based dairy/Beef finishing

Dairy replacements /Beef stockers

Sheep and goats, Cow-calf, Horses
Paddock #’s
So how many paddocks do I
need?
 It depends
 length of grazing period desired
 producer goals, livestock performance
 length of rest period needed
 Changes seasonally

rest period
grazing period
+ # herds = paddock #
Grazing period Needs
 Plant based:
 2 - 5 days fast
grow
 5 - 9 days
moderate
 9 - 12 slow
growth
 Animal
performance:
 .5 - 1 day dairy
cows/finishing
 1 - 2 days
growing/fattening
 2 - 5 days lactating
beef cattle, sheep,
horses
4000
3500
3000
2500
2000
1500
1000
500
0
Impact of Days on Paddock
on Organic Matter Intake
30
Stem
Leaf
1
2
3
4
5
6
7
8
9 10 11 12 13
Days on Pasture
OM Intake (lb/hd/day)
DM Available (lb/acre)
Impact of Days on Paddock on
Change in Sward Composition
25
20
15
10
5
0
1
2
3
4
5
6
7
8
9 10 11 12 13
Days on Pasture
Rest period needs
 Rest period needs:
15 - 20 days during rapid growth
20 - 30 days during moderate growth
30 - 45 days during slow growth
40 - 60 days very slow growth
How many paddocks do I
need?
 Paddock Number = rest period
grazing period + 1
 Ex:
20 day rest period - spring
2 day grazing period
+1 = 11
40 day rest period - summer
2 day grazing period
+ 1 = 21
How many paddocks do I
need?
 Or:
40 day rest period
4 day grazing period + 1 = 11
Optimum Paddock #’s
based on Livestock Type
(Rule of Thumb)
Livestock type
Grazing Period
(Days)
Paddock #
Dairy/grass
finishing
0.5 – 1
20 - 80
Dairy heifer / beef 1 - 2
stockers
16 - 40
Cow/calf, Sheep,
Goats, Horses
8 - 16
2-5
Summary
 Animals delight most to feed on fresh plants
 Animals supplied with this kind of food would be
quickly fatted
 If a farmer divided his land into 15 - 20 equal
divisions,
 Stopped his beasts from roaming indiscriminately
 Put the whole number of his beasts into one of
these divisions
 Have the number of beasts so great as to
consume the best part of the grass in one day
Summary cont’d:
 Give them a fresh park every morning to repeat
the same repast
 Have so many parks as days required to
advance the grass to the proper length after
being eaten fare down
 So the first park would be ready to receive
them after going over all the others
 So they might be carried round in a constant
rotation
 James Anderson, Scottish Agriculturalist, 1777
The End
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