Grazing Management Principles for Rangelands

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Grazing Management Principles for Rangelands

• Mort Kothmann
• Texas AM University

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Four Basic Principles of Grazing Management

• Stocking rate
• Season of grazing
• Distribution of grazing across landscape
• Match kinds and classes with the rangeland
  vegetation, topography and climate

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Grazing Management ConceptsBasic tenets of
grazing management

• Grazing intensity (degree of use)
• Light moderate heavy extreme
• Methods for monitoring degree of use
• Key area method (Key species)

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Grazing Intensity

• A certain amount of plant biomass must remain to
  maintain to assure health of animals, plants and
  soil
• Herbivore diet
• Plant vigor and reproduction
• Soil stability

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Grazing Intensity

• As annual precipitation declines, sustainable
  level of forage utilization generally decreases
• Sustainable intensity of grazing is directly
  related to availability of water and soil
  nutrients
• Greater resource availability increases
  proportional allocation to shoot relative to root

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Grazing Intensity

• Recommended levels of use based on field
  estimates and (harvest efficiencies)
• Ryegrass (water N unlimited) 75 (70-80)
• Coastal Bermudagrass pasture 50 (40-60)
• Humid tall grassland 40-50 (20-30)
• Semiarid grasslands 20-30 (15-20)
• Arid SW Intermountain West 15-20 (10-15)
• The more arid the land, the lower the sustainable
  intensity of use.

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Monitoring Range Utilization

• Key Species Method for monitoring use
• Monitor utilization of 1-3 key species that are
  abundant, productive, and palatable (decreasers
  or increasers) rather than monitor many species
• Assumption use of entire range is optimal when
  use of key species is optimal
• Key species are moderately used 30-40
• Secondary species are lightly used 10-25
• Ice-cream plants may be overused gt40

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Monitoring Range Utilization

• Key Area method for monitoring range use
• Monitor an area that is representative of
  overall range condition, trend, and degree of
  seasonal use
• No rangeland is uniformly used some sacrifice
  areas will occur due to area selectivity
• Heavy use Clipped or mowed appearance
• gt50 of fair or poor forage plants used
• Moderate Use
• 50 of good or fair forage plants used
• Light use
• Only choice plants used

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Monitoring Range Utilization

• Key Area method for monitoring range use
• Optimal stubble height in key areas following
  grazing vary
• Tall-grasses
• 30-35 cm (12-14 inches)
• Mid-grasses
• 15-20 cm (6-8 inches)
• Short-grasses
• 5-8 cm (2-3 inches)

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TGM for Monitoring Degree of Use

• Using the Demand Day (DD) as a measure of animal
  production and maintenance from the pasture.
• Energy required for maintenance and growth is
  estimated from animal weights and expressed as
  DD.
• Productivity of the pastures is estimated from
  observed animal production and degree of use on
  the pasture.

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Season of Use

• Yearlong
• Used primarily in tropical sub-tropical
  climates
• Seasonal
• Temperate to cold climates
• Tame pastures
• Rotational
• Grazing Systems (This will be covered in a
  separate presentation.)

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Length of Grazing Season vs Growing Season

• Rangelands Grazing season is generally longer
  than the growing season. This requires
  stockpiling forage for use during the non-growing
  season. This frequently involves very light use
  during the peak growing season.
• Tame Pasture Grazing season is matched with the
  growing season to harvest forage near maximum
  quality. Stockpiling forage usually involves
  shortening the grazing period during active
  growth.

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Timing of Grazing

• Effect of grazing varies according to
• Season of use -- Plants are more resistant to
  intense herbivory during dormancy than in active
  growth.
• Phenological stage of plant -- Defoliation in
  spring when plants start growth may be less
  harmful than in fall when plants are flowering
  and maturing.
• Opportunity for regrowth Will plants be able to
  produce new leaves and develop strong root
  systems prior to entering dormancy following
  defoliation?

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Grazing DistributionAnimal Selectivity

• Area distribution
• Landscape
• Patch
• Feeding station
• Species selective grazing
• Plant part selective grazing
• Live or dead
• Leaf of stem

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Area Selection

• Factors affecting area selection include
• Distance from Water
• Vegetation Type
• Topography (Slope)
• Range Site (Soils)
• Weather
• Animal pests such as flies
• Kind class of animal
• Management practices such as supplementation

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Distance from Water

• Recommended distances between watering points
  vary according to terrain, species of animal, and
  breed of livestock
• General recommendations
• Rough country 0.5-mile max
• Rolling country 1.0-mile max
• Flat sandy country 1.5-mile max
• Flat country 2.0-mile max

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Vegetation Type

• Herbivores select areas with vegetation that best
  meets their nutritional needs
• Bulk grazers prefer open grasslands
• Cattle, Buffalo, White rhinos
• Browsers prefer wooded areas
• Mule deer, Giraffes, Black rhinos

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Topography
Figure 10.2 Relationship of slope gradient to the
percentage of observations of cattle, feral
horses, deer, and bighorn sheep. (From Ganskopp
and Vavra 1987. Reprinted with permission.)
Cattle Horses Deer Bighorn
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Improving Livestock Distribution

• Provide supplemental feeds/mineral licks
• Cattle move from water to grazing to salt
• Change location of salt-mineral licks
• Place salt away from water in areas that grazing
  animals are avoiding
• Grazing systems that reduce pasture size and
  significantly increase animal density may improve
  livestock grazing distribution.

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Improving Livestock Distribution

• Prescribed burning
• Removal of previous years growth
• Greater access to new plant growth
• Early spring fires can
• Increase soil temperature
• Initiate growth
• Improve forage quality
• Encourage earlier grazing

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Improving Livestock Distribution

• Adjust kind/class of livestock
• Changing animal species can improve livestock
  distribution depending on
• Vegetation composition
• Water distribution
• Topography
• Because of non-uniform plant composition,
  multi-species animal production systems can
  increase
• Herbivore distribution
• Vegetation use
• Animal production

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Improving Livestock Distribution

• Fencing can be used to control
• Area selective grazing
• Season of use
• Rotational grazing systems
• Use of high-value forages such as hay crops
• Movement of wildlife

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Livestock Distribution

• Negative Aspects of Fencing
• Cost prohibitive where productivity is low
• Electric fences are less costly to construct than
  standard barbed wire but more expensive to
  maintain
• Restrict movement of some wild species
• High-fencing to control game species

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Kind Class of Animal

• Kind of animal (species)
• Cattle, sheep, goat, horse, wildlife species
• Class of animal (age, sex, physiological status)
• Reproductive -- pregnant or open
• Age -- mature or young
• Lactating or dry
• Adaptation to climate and forage quality
• Breed of animal
• Genetic potential for growth and lactation

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Choice of Kind Class of Animals

• Match animal genetics with forage quality
• Match the grazer with the landscape and the kinds
  of vegetation