Grazing Management Principles for Rangelands by ryq78127

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									  Grazing Management
Principles for Rangelands
       Mort Kothmann
     Texas A&M University
        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
 Grazing Management Concepts
Basic tenets of grazing management

► Grazing   intensity (degree of use)
   Light – moderate – heavy – extreme
► Methods   for monitoring degree of use
   Key area method (Key species)
           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
             Grazing Intensity
► Asannual 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
           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.
   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 – >40 %
   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
           >50 % of fair or poor forage plants used
     ►Moderate      Use
           50 % of good or fair forage plants used
     ►Light   use
           Only choice plants used
   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)
 TGM for Monitoring Degree of Use

► Usingthe 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.
                 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.)
             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.
              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?
            Grazing Distribution:
             Animal Selectivity
► Area   distribution
   Landscape
   Patch
   Feeding station
► Species selective grazing
► Plant part selective grazing
   Live or dead
   Leaf of stem
               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
           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
               Vegetation Type
► Herbivoresselect 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
                                    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.)
Percent of Observations




                          70
                                    Cattle
                          60        Horses
                          50        Deer
                                    Bighorn
                          40
                          30
                          20
                          10

                               10     20      30   40   50    60   70   80+
                                              Percent Slope
  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

► Grazingsystems that reduce pasture size
 and significantly increase animal density
 may improve livestock grazing distribution.
  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
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
  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
      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
          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
  Choice of Kind & Class of Animals

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

								
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