Managing Natural Resources – Stocking Rate, Carrying Capacity & Animal UnitsGillespie County Beef & Range Field DayMay 12, 2011

R.K. LyonsR.V. Machen

Goals

• Personal

• Resources

–Soil

–Plants

–Animals

• How are they related?

“I love ground nesting birds, especially quail. How can I draw them into the yard?”

How are these goals related?

What is “Job One”?

Yellow Indiangrass Little Bluestem Big Bluestem Switchgrass

Wright’s Threeawn KR Bluestem Prairie Coneflower

Wildlife Management

How can I monitor progress toward

achieving my goal(s)?

Range Health

Why is Rangeland Health

Important?

Robert K. Lyons, Ph.D.

Extension Range Specialist

Rangeland Health Definition

Degree of sustained integrity of:

Soils

Ecological processes

Photosynthesis

Nutrient cycling

Rangeland Management Standard

Minimum:

prevent human induced loss of rangeland

health

Rangeland Health Thresholds

Healthy

At risk

Unhealthy

Health Criteria & Thresholds

Healthy At Risk Unhealthy

No movement Moving on site Moving off site

Soil Stability

Nutrients/Energy & Thresholds

Healthy At Risk Unhealthy

Good distribution Fragmented Fragmented; large barren areas; pedestaled plants

Plants & Litter

Leaf Removal & Root Growth

0

20

40

60

80

100

0 20 40 60 80 100

Leaf Volume Removed, %

Reduced Root

Growth, %

Heavy, Frequent Defoliation

Reduces root growth & sizewater infiltration water absorption nutrient absorption

Loss of competitive advantage

Forage Residue Levels

Vegetation Type Lb./ac Minimum Stubble Height,

inTallgrass 1200-1500 12-14

Midgrass 750-1100 6-8

Shortgrass 300-500 2-3

How grass grows

How Grasses Grow

Growing point close to ground

protected produce leaves 1-2 yrs

elevated unprotected eaten/makes seedhead: dies

Growing Point Elevation &

Grazing Resistance

Grass species Growing point elevation/ reproductive tiller ratio

Grazing resistance

Buffalograss Remain close to ground High

Little bluestem Elevation late w/ large number reproductive tillers

Moderate

Sideoats grama Elevation late w/ large number reproductive tillers

Moderate

Switchgrass Early Low

Yellow Indiangrass Early Low

Johnsongrass High number reproductive tillers

Low

Evaporation

Infiltration

Transpiration

Runoff

Rainfall Movement From Range Watersheds

Percolation

Grazing Management

• Leaving a forage residue Protects soil Increases rainfall

effectiveness Increases forage

production

0

500

1000

1500

2000

2500

3000

3500

4000

Fo

ra

ge P

ro

du

cti

on

,

lbs/

ac

100 500 1500

January Forage

Residue, lbs/ac

16.5

16.9

9.7

Forage Residue & Rainfall Effectiveness

Animal Unit- relates different animals to a common base – forage consumption.An animal unit is the number of animal(s) which consume 26 pounds of forage (DM) per day.

1,000 lb cow5 sheep6 goats7 deer

17 jackrabbits52 free-range hens

“Animal Unit”wt.

Aoudad 200Axis 160Blackbuck 75Fallow 130Mouflon 120Red Deer 450Sika 145

Whitetail 100

Cattle 1000Sheep 90Spanish goat 90Boer X goat 135

from Exotics on the Range, Mungall & Sheffield, 1994

“Animal Unit”wt. intake

Aoudad 200 0.035Axis 160 0.035Blackbuck 75 0.04Fallow 130 0.035Mouflon 120 0.035Red Deer 450 0.03Sika 145 0.035

Whitetail 100 0.035

Cattle 1000 0.026Sheep 90 0.04Spanish goat 90 0.04Boer X goat 135 0.04

from Exotics on the Range, Mungall & Sheffield, 1994

“Animal Unit”wt. intake lb/day

Aoudad 200 0.035 7.00Axis 160 0.035 5.60Blackbuck 75 0.04 3.00Fallow 130 0.035 4.55Mouflon 120 0.035 4.20Red Deer 450 0.03 13.50Sika 145 0.035 5.08

Whitetail 100 0.035 3.50

Cattle 1000 0.026 26.00Sheep 90 0.04 3.60Spanish goat 90 0.04 3.60Boer X goat 135 0.04 5.40

from Exotics on the Range, Mungall & Sheffield, 1994

“Animal Unit”wt. intake lb/day AUE hd/AU

Aoudad 200 0.035 7.00 0.27 3.7Axis 160 0.035 5.60 0.22 4.6Blackbuck 75 0.04 3.00 0.12 8.7Fallow 130 0.035 4.55 0.18 5.7Mouflon 120 0.035 4.20 0.16 6.2Red Deer 450 0.03 13.50 0.52 1.9Sika 145 0.035 5.08 0.20 5.1

Whitetail 100 0.035 3.50 0.13 7.4

Cattle 1000 0.026 26.00 1.00 1.0Sheep 90 0.04 3.60 0.14 7.2Spanish goat 90 0.04 3.60 0.14 7.2Boer X goat 135 0.04 5.40 0.21 4.8

from Exotics on the Range, Mungall & Sheffield, 1994

How many 1,000 lb cow’s are out there?

1200 lb 1200 lb

Production Stage ……………. Early Lactation

Daily Feed ………………….…. Good Bermudagrass hay11% CP, 54% TDN

Daily DM intake 25.5 lbDaily weight change -0.98 lb

Days to Lose 1 BCS 94

Daily DM intake 27.7 lbDaily weight change -2.88 lb

Days to Lose 1 BCS 29http://www.ansi.okstate.edu/exten/cowculator/

Daily DM intake 5.6 lb

Head/AU 4.6

160 lb 100 lb

Daily DM intake 3.5 lb

Head/AU 7.4

1 AU consumes = 26 lb DM/day

Daily DM intake 4.0 lb

Head/AU 6.4

100 lb 180 lb

Daily DM intake 7.2 lb

Head/AU 3.6

1 AU consumes = 26 lb DM/day

Stocking RateCarrying Capacity Grazeable Acres

Carrying Capacity, Stocking

Rate, & Grazeable Acres

Robert K. Lyons, Ph.D.Extension Range Specialist

Stocking Rate vs. Carrying Capacity

•Stocking rateAcres allotted to an animal Acres/animal unit/year

• Carrying capacityStocking rate possible w/o resource damageNumbers not set in stone, only guidelines

Carrying Capacity/Stocking

Rate Considerations

•Take half 25% to livestock 25% to trampling, insects, decay

•Leave halfProtect soil Plant vigor & protection

Take Half-Leave Half

Gillespie County

Major Soil Component Carrying Capacity

Soil Annual

Production, lb/ac

25% Production to

Livestock, lbs/ac

Carrying Capacity,

Ac/AUY

1 900-1800 225-450 42 21

2 1801-2800 450-700 21 14

3 2801-3500 700-875 14 11

4 3501-4500 875-1125 11 18

5 4501-6000 1125-1500 8 6

Low Stony Hill

23%

Shallow

16%

Clay Loam

11%Redland

8%Loamy Bottomland

8%

Steep Rocky

6%

Steep Adobe

6%

Tight Sandy Loam

4%

Sandy

4%

Deep Redland

2%

Adobe

2%

Granite Hill

2%

Loamy

Sand

1%

Shallow

Ridge

1%

ShallowGranite

1%

Stony

Loam

1%

Red Sandy Loam

1%

Sandstone

Hill

1% Red

Savannah

1%

Sandy Loam

1%

Pits Gypsum

0%

Rock

Outcrop

0%

Granite Gravel

0%

Serpentine

0%

Red Sandy

0%

Gillespie County

Ecological Sites, %

Low Stony Hill

152,125

Shallow

110,765Clay Loam

75,382

Redland

56,107

Loamy Bottomland

50,864

Steep Rocky

41,490

Steep Adobe

38,162

Tight Sandy Loam

28,729Sandy

24,175

Deep Redland

16,815Adobe

11,448

Granite

Hill

10,138

Loamy Sand

9,221

Shallow

Ridge

8,456

ShallowGranite

7,628

Stony

Loam

5,962

Red Sandy

Loam

5,615

Sandstone Hill

4,838

Red

Savannah

4,021

Sandy

Loam

3,762

Pits

Gypsum

3,207

Clay

Flat

3,146

Rock

Outcrop

2,816

Granite

Gravel

1,494

Serpentine

781Red

Sandy

353Dams

11

Pits Mine

3

Gillespie County

Ecological Site, Acres

Low Stony Hill

Theoretical Carrying Capacities

0

5

10

15

20

25

30

Favorable Average Unfavorable

9

14

28

Carrying

Capacity,

Ac/AUY

Rainfall

Stocking Rate Perspectives

Range resource Animal performance

Stocking Rate Considerations

• Proper stocking rate (carrying capacity) example:30 ac /animal unit/year

• Animal unit (1000-lb cow)Forage demand, 26 lbs/day

• 1200-lb cowForage demand, 1200 lbs x 0.026 = 31 lbs/day

Animal unit equivalent, 31 lbs ÷ 26 lbs = 1.2 Stocking rate, 30 ac/AUY x 1.2 = 36 ac/cow

Animal Size

Stocking Rate Considerations

• Proper stocking rate (carrying capacity) example:30 ac/animal unit/year

• 1200-lb cow, weaning 500-lb calf

Forage demand, 1200 lbs x 0.026 = 31 lbs/day Animal unit equivalent, 30 lbs ÷ 26 lbs = 1.2 Stocking rate, 1.2 x 30 ac/AUY = 36 ac/cow

• 1200-lb cow, weaning 600-lb calf

Forage demand, 1200 lbs x 0.03 = 36 lbs/day Animal unit equivalent, 36 lb ÷ 26 lb = 1.4 Stocking rate, 1.4 x 30 ac/AUY = 42 ac/cow

Animal Productivity

Stocking Rate Considerations

•Ranch/pasture size• Brush cover/density• Topography• Distance to water • Forage preference

Grazeable Acres

GPS Collars

Gravelly Redland:Low Stony Hill

Preference

2.5:1

Edwards Plateau Ranch 2

8173

25

00

10

20

30

40

50

60

70

80

90

Use, %

1 2 3 4

Brush Density Score

Rock Cover, % Use, % No Use

<28 68 32

>28 12 88

Forage Preference

Slope

0102030405060708090

100

Cumulative GPS

Positions, %

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29Slope, %

Grazeable Acres

Distance to Water Percent Use

0.5 1001.0 901.25 801.5 601.75 402.0 202.5 10

Water

Access

N & S

Available

Gravelly Redland

Low Stony Hill

Gravelly Redland

Low Stony Hill

Water

Access

North Only

Gravelly Redland

Low Stony Hill

Water

Access

South Only

Edwards Plateau Ranch 3

Deep Redland

1%

Gravelly Redland

3% Redland

8%

Low Stony Hill

37%

Steep Rocky

51%

Edwards Plateau Ranch 3

Edwards Plateau Ranch 3-D View w/ GPS Locations

39% area used 41% GPS points on 9% area SR: 21 ac/cowEffective SR: 9 ac/cow

Carrying Capacity &

Stocking Rate

• Monitoring: can’t set it & forget it Range resource Forage residue Range health indicators

Animal performance Body condition scores Gain records

How Do You Know Your’re Getting it Right?

Herbivores – Dietary preferences?

Annual Diet Composition, %

81

127

Cattle

Grass

Forbs

Browse6117

22

Sheep

Grass

Forbs

Browse

from What Range Herbivores Eat and Why, Lyons et al., B-6037

Annual Diet Composition, %

45

12

43

Goats

Grass

Forbs

Browse

12

3652

Deer

Grass

Forbs

Browse

from What Range Herbivores Eat and Why, Lyons et al., B-6037

% Browse0

50100

10 23 50 6530

Approximate Annual Diet –% Browse

from “The Use and Management of Browse in the Edwards

Plateau of Texas”, NRCS Pub., 1994

Competition Among DeerKerr Wildlife Area, 1971

• 96 acre enclosure

– 6 whitetail deer

– 6 sika deer

• No livestock

• Primary browse

– Shinoak

– Liveoak

• Mid 70’s = record rainfall

Population Dynamics – Whitetail & Sika

0

10

20

30

40

50

60

70

1971 1972 1973 1974 1975 1976 1977 1978 1979

# h

ead

Whitetail

Sika

Heavy browsing

of shinoak

No acorn crop All browse

depletedW. Armstrong, 1984

Diet Preference

Thank you