Grazing Management Principles for Rangelands

1. Grazing Management Principles for Rangelands Mort Kothmann Texas A&M University

2. 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

3. 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)

4. 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

5. 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

6. 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.

7. 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 %

8. 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

9. 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)

10. 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.

11. 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.)

12. 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.

13. 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?

14. Grazing Distribution:Animal Selectivity • Area distribution • Landscape • Patch • Feeding station • Species selective grazing • Plant part selective grazing • Live or dead • Leaf of stem

15. 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

16. 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

17. 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

18. 70 60 50 Percent of Observations 40 30 20 10 10 20 30 40 50 60 70 80+ Percent Slope 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

19. 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.

20. 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

21. 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

22. 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

23. 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

24. 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

25. Choice of Kind & Class of Animals • Match animal genetics with forage quality • Match the grazer with the landscape and the kinds of vegetation