PowerPoint about the Ecological Aspects of Mob Grazing, by Prof. Edward Rayburn for the Greenbrier Valley Pasture Network, 2012

1. Ecology of
High Density or Mob Grazing
Ed Rayburn
Appalachian Grazing Conference
March 4-5, 2011
Morgantown, WV

2. Pasture-Based Livestock Producers
• In business harvesting solar energy.
• Converting solar energy into food and fiber
products for people.
• Manage
– plants to optimize harvest of solar energy,
– animals to transfer that energy into livestock products,
– cycling of mineral nutrients in the landscape
– to make business socially, economically, and
environmentally sustainable.
• Are pasture ecosystem managers.

3. What we will cover
• Pasture Ecosystem
• Ecological principles/tools
– Light interception with height and date
– Tolerance to shading
– Selective grazing
– Stocking density
• Management Goals
– Toxic tall fescue management
– Legume establishment
– Developing soil organic matter
– Substitution for bush-hogging
– Animal performance (now vs. long term)

4. Pasture Ecosystem
• Climate (average weather)
• Weather (this year)
• Plants
• Grazing animals
• Soil
• Humans

5. Pasture Ecosystem
• Plants
– producers
harvest sunlight
fix nitrogen
cycle nutrients
– forage quality & anti-quality
– plant morphology
grass, legume, forb, shrub, tree (succession)
tall vs. short
rhizome vs. bunch
fibrous vs. tap root
“plastic” growth habit
– plant life history; perennial vs. annual

6. Pasture Ecosystem
• Grazing animals
– primary consumers (cows, sheep, goats, others)
– age, production rate (maintenance, milk, finishing)
• Grazing preferences
– animal species vs. learned behavior
– ability to selectively graze
– rumen size : body size and forage preference or tolerance
• Movement while grazing; cows walk 4 ways
– in file / cow-path
– grazing “front” at low stock densities
– quite, tight “mob” at high stock density
– stampede

7. Pasture Ecosystem
• Soil
– parent material, landscape position
– depth, texture, surface and internal drainage
– organic matter
– soil critters; consumers, decomposers, pests, diseases

10. Pasture Ecosystem
• Humans
– predators
– managers: intentional & unintentional
– fire
• for 10,000 yrs.
• savanna & prairie vs. forest
• bison vs. cattle
– fences
• stocking rate
• stocking density
– grazing management (2 independent factors)
• grazing timing – length of regrowth interval, plant growth cycle, time of year
• (CHO cycle, tiller production, seed production)
• grazing intensity - degree of defoliation
– pasture management and plant species equilibrium
• grazing, multi species grazing, fertilization/liming, fire, herbicides,

11. Ecological principles/tools
• Light interception with height and date
• Tolerance to shading
• Selective grazing
• Stocking density

12. Light Interception by
Pasture Height and Season
1.20
1.00
Light Interception
0.80
Apr & Jun
May
0.60
Jul & Aug
Sep & Oct
0.40
0.20
0.00
0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0
Ruler Height inches

13. Species Differ in Tolerance to Long
Regrowth Periods/Shading
Tolerant (hay type) Intolerant (pasture type)
– Smooth bromegrass – Tall fescue
– Timothy – Orchardgrass
– Reed canarygrass – Perennial ryegrass
– Quackgrass – Kentucky bluegrass
– Red clover (+/-) – White clover
– Alfalfa
– Birdsfoot trefoil
– Native WS grasses

14. Selective Grazing
• The ability of animals to select and
consume forage of higher quality than the
average forage quality in the pasture.

15. Forage Mass vs. Height
Ruler Ht FM/In.Ht. FM/acre
1 382 382
2 371 741
3 359 1076
4 347 1387
5 335 1674
6 323 1938
7 311 2178
8 299 2394
9 287 2586
10 275 2754
11 264 2899
12 252 3019

16. Diet Selection Based on
Initial Pasture Quality and Utilization
Pasture Utilization
Whole
Pasture 0.20 0.40 0.60 0.80
TDN
60 68 65 63 60
65 73 71 68 66
70 79 77 74 72

17. Management Goals
• Toxic tall fescue management
• Legume establishment
• Developing soil organic matter
• Substitution for bush-hogging
• Animal performance (now vs. long term)

18. Application to toxic tall fescue
management
• Establish a long regowth period to open
tall fescue stand through self-shading
• Over-seed forage species that tolerate
long regrowth periods (may already be in
stand)
• Use high stock density grazing to utilize
the forage, walk-in the seed or just open
the stand for the desired species needed
to reduce the toxic tall fescue

19. Species Differ in Tolerance to Long
Regrowth Periods/Shading
Tolerant (hay type) Intolerant (pasture type)
– Smooth bromegrass – Tall fescue
– Timothy – Orchardgrass
– Reed canarygrass – Perennial rye grass
– Quackgrass – Kentucky bluegrass
– Red clover – White clover
– Alfalfa
– Birdsfoot trefoil
– Native WS grasses

20. Application to legume
establishment
• Establish a long regowth period to open forage
stand at soil level through shading
Or
• Use normal rotation cycle
• Overseed legume species adapted to soil and
planned long-term management (at “proper”
time of year)
• Use high stock density grazing to utilize the
forage and walk the seed into the soil

21. Clover seedlings about 9 weeks old

22. August walk-in seeding
1-year latter

23. Developing soil organic matter

24. Why Is SOM Important?
50
Avail. Water Holding Capacity%
45
40
35
30
25
20
15
10
5
0
0 2 4 6 8 10
SOM%

25. Soil Organic Matter Affected by:
• Past management (fertility and grazing)
– Adequate fertility (applied, recycled) stimulates plant
growth
– Rotational grazing to proper height stimulates SOM
• Local environment (temperature rainfall)
– High elevations (further north) have low temperature
high rainfall beneficial to development of SOM
– Low elevations (further south) have higher
temperatures more SOM loss hard to keep high SOM.

26. Soil Organic Change with
Adoption of Rotational Grazing
Soil Organic Matter %
0.0 2.0 4.0 6.0 8.0 10.0 12.0
0
Soil Depth Inches
6
1995
12 1999
1995est
18
24

27. What in the soil do we want to feed?
(feed them and they will come)
• Night crawlers for • Bacteria and fungus
aeration and bacteria for soil structure
– Legumes – Grass
– Young grass – Older high fiber
– Roots material
– Roots

28. Application to developing SOM
• Establish an appropriate regowth period to
maximize root health and optimize forage growth
and quality for the local environment
• Use high stock density grazing at density
appropriate for livestock production goals to
utilize the forage, compress thatch to the
ground, and distribute manure and urine evenly
over landscape

29. Substitution for bush-hogging
or herbicide

30. Bracken fern in no-tilled pasture.

31. Bracken fern not in no-tilled pasture.

32. Application to bush-hogging
• Use high stock density grazing at heavy
stocking density to utilize the forage, walk
thatch and seed heads into the ground,
and distribute manure and urine evenly
over landscape
• Know life history of plants being worked
with
• Consider multispecies grazing

33. Animal performance (now vs. long term)
• Increasing nutrient requirement
– Dry cow mid-trimester
– Dry cow last-trimester
– Early lactation cow
– Stocker steer
– Backgrounding calf
– Dairy cow
• First 4 can be made to work at times
• Make animals work strategically to develop
better forage for the future

35. Forage Mass vs. Height
Ruler Ht FM/In.Ht. FM/acre
1 382 382
2 371 741
3 359 1076
4 347 1387
5 335 1674
6 323 1938
7 311 2178
8 299 2394
9 287 2586
10 275 2754
11 264 2899
12 252 3019

36. Stocking Density and Time vs.
Grazing Pressure/Utilization
• 31 animals at 1450 lbs avg. wt.
• ~45,000 lbs LW on 1.25 acres
• ~36,000 lbs LW/acre
• 900 lbs DMI / 24 hr at 2.5%BW DMI
• 1800 lbs DMI / 48 hrs
• Entry ht 10” or 2754 lbs/a
• Exit FM 954 lbs/a or 2.6”

37. Stock Density for 24 Hours at 2.5% DMI on 10”
Tall Pasture (2750 lbs DM/acre) and its Affect on
Utilization and Residual Forage Height
Residual
Residual forage
Stocking forage height
Forage Ht density mass Utilization est.
10 40000 1750 0.36 5.2
10 50000 1500 0.45 4.4
10 60000 1250 0.55 3.5
10 70000 1000 0.64 2.8
10 80000 750 0.73 2.0

38. Healthy Soil Ecology Balance of
• Food supply (organic matter with adequate
macro- and micro mineral nutrients)
• Physical environment above and below
ground (cover and habitat at all scales)
• Healthy consumers, omnivores, predators,
and predators of predators (diversity)
• Chemical environment (soil oxygen, pH,
fertility)
• Thermal and moisture environment

39. Management Needed to Help the
System (a)
• Soil pH 6.0-7.0 depending on the legume
• Adequate not excessive soil P and K
• Inoculate legume seed with proper bacteria
• Manage nutrients on the farm
– (recycle manure, urine, and organic residues)
• Proper grazing management
– timing and intensity suitable for the forage mixture
• Proper fall grazing
– develop tillers in grasses and stolons of white clovers
– reduce adult clover root curculio activity

40. Take Home
• Above ground we manage plants with animals to capture
solar energy, convert it into marketable livestock
products, cycle nutrients so that our pasture system can
be sustainable.
• This management influences soil organic matter to feed
macro- and microorganisms in the soil.
• This affects the soil’s physical condition, availability of
macro- and micronutrients and soil moisture to plants.
• Understanding how management affects the soil
community assists us in our management of the entire
pasture ecosystem.

41. High Density or Mob Grazing Can
Be a Useful Management Tool
• To accomplish management goals
– Toxic tall fescue management
– Legume establishment
– Developing soil organic matter
– Substitution for bush-hogging
• Keep in mind animal performance (now vs. long term)
• Using ecological principles/tools
– Light interception with height and date
– Tolerance to shading
– Selective grazing
– Stocking density and hoof action/treading
• Stock density, utilization, and regrowth period are
independent management practices with their own
outcome.