Practical #3 Carring Capacity.pptxgggbbv.

Practical #3 Carring Capacity.pptxgggbbv.

1. Determining Carrying Capacity and Stocking Rates Muhammad Rehan

2. Key Points: Proper stocking rate ensures  optimal forage and animal performance . Maintains  long-term health  and  productivity  of grassland resources. Balancing animal demand with forage supply prevents overgrazing or underuse. The carrying capacity and stocking rate determine how many animals a pasture can support without degrading the land. Setting the right rate helps maintain forage productivity, animal health, and ecological balance

3. Factors Affecting Stocking Rate Management goals  of the owner/operator Animal species  (cattle, sheep, goats, horses, etc.) Class of livestock  (dry cow, lactating cow, bull, steer, etc.) Grazing land area  available for the season Rainfall  (amount, timing, and dependability) Each of these factors influences how much forage is available and how efficiently animals can utilize it. For example, lactating cows require more forage than dry cows, and rainfall patterns directly affect grass growth.

4. Environmental and Resource Factors Topography  and  soil type/ecological site Grassland health  (species composition, infiltration rate, annual yield) Livestock water  availability and quality Forage characteristics:  quality, palatability, and productivity Management practices:  rotational grazing, fencing, stocking flexibility Sustainable grazing depends on understanding environmental conditions. Healthy soils, adequate water, and adaptable management systems help maintain forage production, even under challenging weather or market conditions. There is an interaction between  Forage → Animals → Environment → Management  (like a balance triangle)

5. Understanding Forage Demand, Availability, and Duration Forage Demand:  Total forage required by the animal type and class grazing the land. Available Forage:  Amount of forage produced yearly that can safely be consumed by livestock. Duration:  The length of time animals will graze in the area. To determine a correct stocking rate, managers must consider how much forage animals need, how much is available, and for how long they will graze. These factors ensure sustainable forage use and prevent pasture degradation. Forage Demand → Available Forage → Grazing Duration → Stocking Rate

6. Importance of Accurate Estimation Accurate stocking rate depends on  quality data  (field-measured, not estimated). Helps managers set an  initial stocking rate  for pastures. Monitoring forage use  during and after grazing gives valuable feedback. Adjustments  can be made to align with long-term management goals. Reliable field data makes stocking rate calculations more precise. Regular monitoring of forage utilization helps determine if animals are overgrazing or underusing the pasture, allowing for timely adjustments that support both livestock and grassland sustainability.

7. What Is Stocking Rate? Stocking Rate:  Number of specific kinds and classes of animals grazing a land area for a set period. It’s a  key management decision  in any grazing system. Directly affects both  animal performance  and  grassland health . Influenced by vegetation type, livestock class, and grazing method. The stocking rate defines how many animals can graze an area for a given time. It is one of the most critical decisions for ranchers and land managers because it influences the productivity of animals and the sustainability of pasture resources

8. Stocking Rate vs. Carrying Capacity Carrying Capacity:  The  amount of forage  a land unit can produce sustainably. Stocking Rate:  The  number of animals  placed on that land. Stocking rate should  match carrying capacity  to avoid overgrazing. Overuse reduces forage quality; underuse wastes resources. Think of carrying capacity as the “supply” and stocking rate as the “demand.” When these two are balanced, the land remains productive, and animals maintain good health. Too many animals cause degradation, while too few lead to wasted forage

9. Understanding Animal Unit Month (AUM) AUM  = amount of forage consumed by  one animal unit in one month . Based on  age, class, and size  of livestock. Used to  express stocking rates  (e.g., “This pasture supports 125 AUM per year”). Helps compare different livestock types and grazing systems. An Animal Unit Month, or AUM, is a standard unit used in grazing management. It represents the amount of forage one mature cow (with or without a calf) needs for one month. This concept helps managers estimate how many animals a pasture can sustain and for how long. 1 AUM = Forage needed by  1 cow and calf for 1 month

10. Standard Animal Unit and Adjustments Standard Animal Unit (AU):  A  1,000-lb cow  with a  6-month-old or younger calf . Used as the  baseline  to compare other livestock. Different animals have different  Animal Unit Equivalents (AUE)  based on  weight, class, and forage intake . Helps determine  forage demand  for mixed herds or varying livestock sizes. The standard animal unit serves as a reference point for calculating forage needs. A 1,000-lb cow with a young calf equals one animal unit. Larger cows or different species consume more forage, so their AUE is adjusted accordingly to maintain balance between forage supply and animal demand. Illustration showing a  1,000-lb cow + calf = 1 AU , while other animals (e.g., horse = 1.25 AU, sheep = 0.20 AU, goat = 0.15 AU

11. What 1 AU means 1 Animal Unit (AU)  is the  standard measure  used to compare how much forage different animals eat. By definition, 1 AU = one 1,000-lb (450kg) cow (with or without a calf) eating about 26 lb or 12kg ( fed 2.6% DM) of dry forage per day, or 913 lb per month. (estimated for feed wastage) This cow is used as the  baseline  for comparing all other animals. A horse eats  about 25% more forage  than the 1,000-lb cow. So  1 horse = 1.25 AU . In forage terms: 1.25×913lb=1141 lb of forage per month per horse ➡️  Meaning:  You must plan for 25 % more feed or pasture area for each horse than for a 1,000-lb cow.

12. A mature sheep with a lamb eats  only about 20% as much  as a 1,000-lb cow. 0.20×913lb=183 lb of forage per month. ➡️  Meaning:  It takes about  five sheep  (5 × 0.20 AU = 1.0 AU) to eat the same as one cow A mature goat eats  around 15%  of what a cow eats. 0.15×913lb=137 lb of forage per month ➡️  Meaning:  About  6–7 goats  (6.6 × 0.15 AU ≈ 1 AU) consume the same amount of forage as one 1,000-lb cow

13. Animal Type AUE Relative Forage Need Equivalent to 1 Cow 1,000-lb cow + calf 1.00 100 % 1 cow Horse 1.25 125 % 1 horse ≈ 1.25 cows Sheep + lamb 0.20 20 % 5 sheep = 1 cow Goat 0.15 15 % 6–7 goats = 1 cow

14. Animal Unit Equivalents (AUE) Guide Forage Consumption by Animal Type Cattle: 1,000-lb cow with calf →  1.00 AUE  (≈ 913 lb forage/month) 1,200-lb cow with calf →  1.15 AUE  (≈ 1,049 lb forage/month) Mature bull →  1.40 AUE  (≈ 1,278 lb forage/month) Horses:  1.25 AUE (≈ 1,141 lb forage/month) Sheep (with lamb):  0.20 AUE (≈ 182.6 lb forage/month) Goats:  0.15 AUE (≈ 137 lb forage/month) Wildlife: Deer (mature) → 0.15–0.20 AUE Elk → 0.60 AUE

15. These equivalents help translate forage needs across different animal species. For example, six mature goats (0.15 × 6 = 0.9 AUE) consume roughly the same forage as one 1,000-lb cow. Using AUEs allows managers to plan mixed-species grazing systems effectively.

16. Understanding Harvest Efficiency Portion of the plant  impacted by livestock  while grazing. Includes: Forage eaten  by animals. Spoilage/waste  from trampling.(press plant by hooves) Losses  from wildlife and insects. Influenced by : forage type, maturity, distribution, topography, livestock density. Follows the  “Take Half, Leave Half”  rule to maintain regrowth and soil health. Harvest efficiency measures how much of the available forage is actually used by animals versus what remains for plant recovery and ecosystem stability. The “take half, leave half” concept ensures that half the forage remains to protect soil and support plant regrowth.

17. Calculating Harvest Efficiency Expressed as a  percentage (%)  of total forage. Multiply total forage yield by harvest efficiency to find  usable forage . Typical Values: Native pastures (season-long):  25% Wet meadow pastures:  12.5%  (lower due to palatability) Properly managed grazing systems can  increase efficiency  over time. Harvest efficiency converts total forage production into the amount livestock can safely consume. For instance, if total forage is 4,000 lb /acre and harvest efficiency is 25%, then only 1,000 lb /acre should be grazed to protect long-term productivity. Formula: Usable Forage = Total Forage × Harvest Efficiency (%)

18. Improving Harvest Efficiency Rotational grazing  and  controlled stocking  can improve efficiency. Each  1% increase  in harvest efficiency gives a  4% rise  in carrying capacity. Begin with  25%  efficiency and adjust based on  monitoring results . Harvest efficiency isn’t fixed — it can improve with better grazing management. Rotational grazing helps distribute livestock evenly and allows plants to recover, boosting both forage use and pasture longevity.

19. Harvest Efficiency Multipliers Harvest Efficiency (%)  = portion of forage consumed by livestock. Multiplier  = used with  AUM/acre method  to calculate carrying capacity. Higher harvest efficiency → higher carrying capacity. Start points: Wet meadow pastures →  12.5% (Multiplier 0.50) Native rangeland →  25% (Multiplier 1.00) Tame grass/legume pastures →  30% (Multiplier 1.20) Multipliers adjust carrying capacity according to how efficiently forage is harvested. For example, at 25% harvest efficiency (multiplier 1.00), the base carrying capacity stays the same. If management improves efficiency to 35%, the multiplier rises to 1.40—meaning a 40% increase in carrying capacity

20. A small table or bar chart comparing efficiency vs. multiplier Harvest Efficiency (%) Multiplier 12.5 0.50 25 1.00 30 1.20 35 1.40 40 1.60 50 2.00

21. Applying Harvest Efficiency Use  harvest efficiency (%)  for  relative production value  calculations. Use  multiplier values  for  AUM/acre method  calculations. Maintain a  50% “leave” rate  for long-term pasture health. Gradually increase efficiency through  proper grazing management . Harvest efficiency reflects how much forage is used while leaving enough for regrowth. Managers apply these values to refine stocking rates. Improving efficiency without harming plant health leads to better forage utilization and higher overall productivity. Flowchart: Harvest Efficiency (%) → Multiplier → Adjusted Carrying Capacity (AUM/acre)

22. Types of Grazing Lands Rangeland Pastures: Dominated by  native vegetation  (grasses, forbs, shrubs). Managed mainly through  grazing control  rather than cultivation. Include:  natural grasslands, savannas, shrublands, deserts, tundra, alpine areas, coastal marshes, and wet meadows . May be  naturally or artificially revegetated . Rangelands are vast natural ecosystems where vegetation is mainly native. These lands rely on controlled grazing rather than intensive farming. Management focuses on maintaining plant diversity, soil stability, and sustainable forage supply.

23. Tame Grass Pastures Planted grazing lands  with introduced or improved forage species. Managed through  tillage, fertilization, weed control, mowing, or irrigation . Not rotated with crops. Designed for  higher productivity  and easier management than natural rangelands. Tame grass pastures consist of improved or introduced forage species that require more active management. These lands often yield more forage than native rangelands due to better soil fertility and controlled growing conditions.

24. A side-by-side comparison Feature Rangeland Tame Grass Pasture Vegetation Native Introduced Management Grazing control Cultivation, fertilization, irrigation Productivity Moderate High Examples Shrublands, meadows Improved grass-legume fields

25. Calculating Stocking Rate Stocking Rate  helps determine how many animals a pasture can support for a specific time. Use  Animal Units (AU)  and  Animal Unit Months (AUM)  for calculation. The  NDSU Grazing Calculator App  can simplify this process: Android version iOS version Formula: Animal Unit Months (AUM) AU×Months  Grazed (M)=Animal Unit Months (AUM) Stocking rate calculations are based on how many animals graze, their forage consumption (AUE), and the length of the grazing period. Using AUM ensures that forage resources are not overused and that grassland productivity remains sustainable.   Number of Animals → AUE → AU → Months → AUM

26. Example 1 – Cattle Grazing Calculation Example: Cows and Bulls on Pasture Given: 100 cows with calves (1.15 AUE each) grazing for  5.5 months 4 mature bulls (1.50 AUE each) grazing for  2.5 months Calculation: Cows: 100 × 1.15 =  115 AU  × 5.5 =  632.5 AUM Bulls: 4 × 1.50 =  6 AU  × 2.5 =  15.0 AUM Total:  632.5 + 15.0 =  647.5 AUM In this example, the total forage needed for all cattle and bulls over their grazing period equals 647.5 AUM. This figure helps determine whether the pasture has enough forage available for the grazing duration. A simple calculation table showing each step (Animals → AU → AUM)

27. Example 2 – Sheep Grazing Calculation Example: Ewes and Rams on Pasture Given: 250 ewes with lambs (0.20 AUE each) grazing for  5 months 5 rams (0.25 AUE each) grazing for  2 months Calculation: Ewes: 250 × 0.20 =  50 AU  × 5 =  250.0 AUM Rams: 5 × 0.25 =  1.25 AU  × 2 =  2.5 AUM Total:  250.0 + 2.5 =  252.5 AUM For this flock, the total grazing requirement is 252.5 AUM. Managers can compare this to available forage to ensure the land can support these animals sustainably without overgrazing. Example 1 (647.5 AUM)  vs.  Example 2 (252.5 AUM)  to visually show differences in forage demand across livestock types.

28. Calculating Carrying Capacity Carrying Capacity:  The estimated  forage quantity  a pasture can sustainably support. Determines how many animals can graze without damaging vegetation or soil. Two main calculation approaches: Field-based methods  (direct measurement) Regional estimates  (based on USDA NRCS data) Carrying capacity measures the amount of forage that can be grazed while maintaining pasture health. Accurate estimation helps prevent overgrazing and ensures long-term productivity of rangeland or pastures.   Forage Production → Carrying Capacity → Stocking Rate → Sustainable Grazing .

29. Methods for Calculating Carrying Capacity Field-Based Methods: Involve direct measurement of forage production on-site. Provide the  most accurate  results. Detailed steps available in  “Ranchers Guide to Grassland Management IV”  (Sedivec & Printz, 2014). Regional Data Estimates: Use USDA NRCS regional production data. Apply  AUM/acre  or  Relative Production Values ( lb /acre) . Useful when no field samples are available. Field-based methods are preferred because they reflect local conditions. However, when field data are not available, USDA NRCS data provide reliable starting estimates for management planning.

30. Determining Pasture Characteristics Determine your  Major Land Resource Area (MLRA) . Categorize pasture acres by  upland  or  lowland vegetation types . Consider  ecological site  and  soil type  for accuracy. Use mapping tools such as: Web Soil Survey (USDA NRCS, 2013):   websoilsurvey.sc.egov.usda.gov GIS-generated maps Visual field estimates Knowing your MLRA and vegetation types ensures more accurate carrying capacity estimates. Online resources like the USDA Web Soil Survey and SoilWeb mobile app make it easy to identify soil and ecological characteristics.

31. Getting Local Support Assistance and Resources Use  SoilWeb  mobile app for on-site soil identification. Contact your  local NRCS office  or  county Extension agent  for help with data and mapping. Combine local expertise with field data for  most reliable carrying capacity results . Local agricultural offices and digital tools can support managers in refining estimates. Combining professional guidance with real field data helps develop a more accurate grazing plan suited to local conditions. Icons or photos of a smartphone with the SoilWeb app, and a local extension agent assisting a rancher in the field.

32. Carrying Capacity Using AUM/Acre Method Estimating Carrying Capacity (Rangeland Pastures Only) Method applies to  rangeland pastures  only. Multiply the  acres of each vegetation type  by the  estimated stocking rate (AUM/acre) . Repeat for each vegetation type, then  sum all results  to get total AUM available. Adjust final AUM using  harvest efficiency multiplier  (from Table 2). Formula: Carrying Capacity (AUM)=Acres of Vegetation  Type×AUM / acreCarrying  Capacity (AUM) This method estimates how much forage your rangeland can provide based on vegetation type and productivity. Each vegetation type has its own stocking rate, and total AUM represents the full grazing potential of your land before adjustment for efficiency or livestock type. Acres × AUM/acre → AUM for Each Type → Sum → Adjust by Multiplier

33. Converting to AUEM per Acre Calculating Animal Unit Equivalent Months per Acre (AUEM/ac) Once total AUM is known: Divide  total AUM ÷ total acres ÷ AUE Result =  AUEM/ac  (Animal Unit Equivalent Months per Acre) AUE  = animal unit equivalent for your livestock class (from Table 1). Shows  how many acres  are required to support one animal unit for one month. Formula: AUEM/ac=AUM (total)Total  Acres×AUEM /ac ​AUEM per acre tells you the grazing density your land can handle — or in simpler terms, how much land is needed per animal each month. It helps refine stocking plans to match forage supply with livestock demand. Total AUM → ÷ Acres → ÷ AUE → AUEM/acre

34. Estimated Stocking Rate Guide (Table 3) Vegetation Type MLRA 53A&B MLRA 54 MLRA 55A&B MLRA 56 MLRA 58C&D Upland – Loamy 0.66 0.66 0.71 0.85 0.57 Upland – Sandy 0.68 0.66 0.77 0.85 0.55 Upland – Clayey 0.63 0.57 0.66 0.82 0.52 Upland – Shallow 0.60 0.38 0.52 0.60 0.36 Upland – Very Shallow/Thin Claypan 0.30 0.24 0.37 0.43 0.22 Lowland – Overflow 0.96 0.87 1.01 1.15 0.57 Wet Meadow 0.60 0.60 0.60 0.70 0.60

35. This table provides estimated stocking rates for various rangeland vegetation and soil types across major land resource areas (MLRA). Choose the value that matches your pasture’s type and location, then use it in the AUM/acre calculation.

36. Adjusting for Improved Management Using Multipliers to Refine Carrying Capacity If  harvest efficiency  improves (via rotational grazing or good management): Multiply total AUM by the  multiplier  from Table 2. Example: Base AUM = 800 Improved management (35% efficiency; multiplier 1.40) New Carrying Capacity = 800 × 1.40 =  1,120 AUM Better grazing management improves forage use. Applying the multiplier helps quantify how much more livestock your pasture can sustain safely without overgrazing. carrying capacity increase when applying multiplier values

37. Example 3 – Cattle Grazing on Rangeland Example: 1,000-Acre Rangeland Pasture (Cows with Calves) Location:  Steele, N.D. (MLRA 53B1) Livestock:  1,300-lb cow with calf (AUE = 1.22) Pasture composition: 790 ac  Loamy upland  × 0.66 AUM/ac =  521.4 AUM 150 ac  Shallow  × 0.60 AUM/ac =  90.0 AUM 50 ac  Overflow  × 0.96 AUM/ac =  48.0 AUM 10 ac  Wet meadow  × 0.60 AUM/ac =  6.0 AUM Total = 665.4 AUM Calculation: Carrying Capacity=665.4 AUM1,000 acres=0.67  AUM/ac.(665.4/1000=0.67). Carrying Capacity (after adjusting for use efficiency 1.22) (1.22-0.67=0.55),  0.55 AUM per acr . Each acre can  actually  support 0.55 cows per month 1÷0.55=1.82 acres per month Land Requirement per Animal.

38. This rangeland supports approximately 0.55 AUEM per acre, meaning each cow-calf pair requires 1.82 acres per month. This helps landowners plan sustainable grazing periods and stocking rates based on pasture productivity. If you have 10 cows, you’ll need  10 × 1.82 = 18.2 acres  of good pasture to feed them for one month

39. Example 4 – Sheep Grazing with Improved Management Example: Managed Grazing with Sheep and Lambs** Same 1,000-acre rangeland as Example 3. Livestock:  Mature sheep with lambs (AUE = 0.20). Improved management:  35% harvest efficiency →  Multiplier = 1.4 (Table 2) Calculation: 671.7 AUM × 1.4 =  940.4 AUM Carrying capacity = 940.4 ÷ 1,000 =  0.94 AUM/ac AUEM/ac = 0.94 ÷ 0.20 =  4.7 AUEM/ac Land required = 1 ÷ 4.7 =  0.21 acre per sheep per month With better grazing management and rotational systems, harvest efficiency improves, resulting in greater forage utilization. This example shows how efficiency boosts carrying capacity, reducing land needed per animal from 1.82 acres to just 0.21 acre per month.

40. Quick Conversion Tip Converting Between AUM/ac and ac/AUM To convert  AUM/ac → ac/AUM , divide  1 by AUM/ac . Example: 0.67 AUM/ac → 1 ÷ 0.67 =  1.49 ac/AUM Use this conversion to quickly estimate  land area needed  per animal unit. Conversions make it easier to visualize how much land each animal unit requires. This is particularly useful when comparing grazing plans across different pastures or livestock types. 1 ÷ AUM/ac = ac/AUM with a short example beside it (0.67 → 1.49 ac/AUM)

41. Carrying Capacity Using RPV Method Estimating Carrying Capacity (Relative Production Values Method) Used for  rangeland and tame grass pastures . Involves estimating forage production ( lb /acre) based on  vegetation type and land resource area (MLRA) . Steps: Multiply  acres of vegetation type × RPV ( lb /ac) . Multiply by  harvest efficiency (%)  (Table 2). Divide by  913 lb  (monthly forage need per AU). Result =  Total AUM available . Formula: AUM=( Acres×RPV×Harvest  Efficiency)/913

42. This method estimates forage-based carrying capacity using production data (RPV) and harvest efficiency. It’s more versatile than the AUM/acre method because it can be applied to both rangeland and tame pastures   Acres × RPV → Harvest Efficiency → ÷ 913 lb → AUM

43. Interpreting Results Expressing Carrying Capacity Once total AUM is calculated: Divide  AUM ÷ total acres ÷ AUE  →  AUEM/ac . AUE  = Animal Unit Equivalent for livestock type (from Table 1). Converts total forage production into  acres needed per animal per month . Formula for land requirement: Acres per Animal per Month=1/AUEM/ac This step translates forage production into practical stocking values, showing how many acres are needed per animal each month based on their class or weight.

44. Relative Production Value (RPV) Table Vegetation Type / Ecological Site MLRA 53A&B MLRA 54 MLRA 55A&B MLRA 56 MLRA 58C&D Upland – Loamy 2,400 2,400 2,800 2,850 2,100 Upland – Sandy 2,500 2,400 2,800 2,850 2,000 Upland – Clayey 2,300 2,100 2,600 2,700 1,900 Upland – Shallow 2,200 1,330 2,100 2,150 1,300 Very Shallow / Thin Claypan 1,100 800 1,350 1,050 800 Lowland – Overflow 3,500 3,200 3,800 3,800 2,650 Wet Meadow / Sub-Irrigated 4,500 4,250 4,600 4,500 4,000

45. The table shows average forage production (in pounds per acre) for different vegetation types under various MLRAs. Multiply your pasture’s acres by the appropriate RPV to estimate total annual forage production.

46. Applying the Method Putting It All Together Steps Recap: Identify vegetation types and acres. Select RPV values from Table 4. Apply harvest efficiency from Table 2. Divide total by  913 lb /AUM  to get AUM available. Convert to  AUM/ac  and then  AUEM/ac  for your livestock type. For improved management, use  higher harvest efficiency multipliers . Convert units as needed: AUM/ac → ac/AUM:  divide 1 by AUM/ac. This method allows flexibility across pasture types and management systems. Increasing harvest efficiency or improving pasture condition can significantly raise carrying capacity while keeping grazing sustainable. Vegetation Type → RPV → Harvest Efficiency → AUM → AUEM/ac → Acres/Animal

47. Example 5 – Rangeland Carrying Capacity (RPV Method) Example: Calculating Carrying Capacity Using Relative Production Values (RPV) Pasture size:  1,000 acres near Steele, N.D. (MLRA 53B1) Livestock:  1,300-lb cow with calf ( AUE = 1.22 ) Grazing period:  Season-long Pasture composition: Loamy upland – 790 acres Shallow – 150 acres Overflow – 50 acres Wet meadow – 10 acres

48. Step-by-Step Calculation Step 1 – Find Forage Production (using RPV Table): Multiply the acres of each vegetation type by its  Relative Production Value (RPV) . Site Type Acres RPV (lb/ac) Total Forage (lb) Loamy 790 2,400 1,896,000 Shallow 150 2,200 330,000 Overflow 50 3,500 175,000 Wet Meadow 10 4,500 45,000 Total 1,000 2,446,000 lb

49. Step 2 – Apply Harvest Efficiency: Only part of this forage is available for grazing. For uplands →  25% efficiency For wet meadow →  12.5% efficiency Site Type Total Forage (lb) Efficiency Forage Available (lb) Loamy 1,896,000 0.25 474,000 Shallow 330,000 0.25 82,500 Overflow 175,000 0.25 43,750 Wet Meadow 45,000 0.125 5,625 Total 605,875 lb

50. Step 3 – Convert Forage to Animal Unit Months (AUM): Each animal unit eats about  913 lb of forage per month . AUM=Available Forage/913 Site Type Available Forage (lb) ÷ 913 AUM Loamy 474,000 519.2 Shallow 82,500 90.4 Overflow 43,750 47.9 Wet Meadow 5,625 6.2 Total 663.7 AUM

51. Expressing Carrying Capacity AUM per Acre: 663.7AUM÷1,000ac=0.66AUM/ac Acres per AUM: 1÷0.66=1.51ac/AUM1 Adjust for Livestock Size (AUE = 1.22): 0.66AUM/ac÷1.22=0.54AUEM/ac or 1÷0.54=1.85 acpercowpermonth Interpretation (Plain Language): This 1,000-acre pasture can  sustainably feed  the equivalent of  one 1,300-lb cow with calf  on  1.85 acres for one month . The entire pasture produces about  664 AUM  of usable forage in a season. These calculations help the rancher decide how many animals can graze without overusing the pasture.

52. Result Value Meaning Total AUM 663.7 Total forage months available AUM/ac 0.66 Forage available per acre AUEM/ac 0.54 Adjusted for 1,300-lb cow with calf Acres per Cow/Month 1.85 Land needed per cow-calf pair

53. Example 6 — Managed Grazing with Sheep (RPV Method) 1,000-Acre Rangeland, Approved Grazing System (Sheep + Lambs) Location:  Near Steele, N.D. (MLRA 53B1) Livestock:  Mature sheep with lambs ( AUE = 0.20 ) Pasture mix: Loamy upland:  790 ac Shallow:  150 ac Overflow:  50 ac Wet meadow:  10 ac Management:  Approved grazing system → higher harvest efficiency for uplands ( 35% ); wet meadow  12.5% Because grazing is well-managed, we can safely use a higher harvest efficiency on uplands (35%). This increases usable forage and total AUM compared with season-long, continuous grazing

54. Step-by-Step Calculation (RPV → Usable Forage → AUM) From Production (lb/ac) to AUM Step 1 — Forage production using RPV (Table 4): Site type Acres RPV (lb/ac) Total forage (lb) Loamy 790 2,400 1,896,000 Shallow 150 2,200 330,000 Overflow 50 3,500 175,000 Wet meadow 10 4,500 45,000

55. Step 2 — Apply harvest efficiency: Uplands at  35% ; Wet meadow at  12.5% Site type Total forage (lb) Efficiency Usable forage (lb) Loamy 1,896,000 0.35 663,600 Shallow 330,000 0.35 115,500 Overflow 175,000 0.35 61,250 Wet meadow 45,000 0.125 5,625

56. Step 3 — Convert usable forage to AUM Each AU eats  913 lb/month Site type Usable forage (lb) ÷ 913 AUM Loamy 663,600 726.8 Shallow 115,500 126.5 Overflow 61,250 67.1 Wet meadow 5,625 6.2 Total 926.6 AUM

57. Expressing and Interpreting Capacity AUM/ac, AUEM/ac, and Acres per Animal AUM per acre: 926.6 AUM ÷ 1,000 ac =  0.93 AUM/ac Acres per AUM (quick conversion): 1 ÷ 0.93 =  1.08 ac/AUM Adjust for sheep AUE (0.20): 0.93 AUM/ac ÷ 0.20 =  4.65 AUEM/ac Land per sheep per month =  1 ÷ 4.65 ≈ 0.22 ac With good rotational management, this pasture can support  far more grazing . Each mature sheep with lamb needs only  about 0.22 acre per month , thanks to higher harvest efficiency. A “before vs. after” bar showing total AUM: Season-long (cow example):  ~664 AUM Managed system (sheep):  ~927 AUM

58. Management Recommendations Best Practices for Sustainable Grazing Management Stocking rate ≤ Carrying capacity Never exceed carrying capacity to protect rangeland health. Stocking rate may be set  lower  for ecological or management goals. Carrying capacity depends  on the  current ecological site condition . Reference:  R1556 – Ecological Sites of North Dakota www.ag.ndsu.edu/pubs/ansci/range/r1556.pdf Keeping stocking rates below or equal to carrying capacity helps maintain plant cover, soil quality, and long-term productivity. Always consider site health before setting grazing levels. A balanced scale showing  Stocking Rate  on one side and  Carrying Capacity  on the other — labeled “Keep in Balance.”

59. Monitoring and Evaluation Importance of Monitoring Grazing Performance Implement  monitoring tools  to track: Forage use Grazing pressure Progress toward management goals Reference:  R1780 – The North Dakota Grazing Monitoring Stick www.ag.ndsu.edu/pubs/ansci/range/r1780.pdf Monitoring is essential to avoid overgrazing and to adjust management based on real pasture conditions. Tools like the grazing stick make measuring utilization simple and practical.

60. Adaptive Stocking Strategies Using Local Knowledge and Adapting to Conditions Use  local experience and historical data  to refine stocking rates. If forage health and productivity meet objectives, rates may be maintained. Adjust early during droughts  to prevent pasture degradation. Reference:  R1819 – Strategies for Managing Drought in the Northern Plains www.ag.ndsu.edu /pubs/ ansci /range/r1819.pdf Local knowledge is a valuable management tool. In drought or poor growth conditions, early reductions in livestock numbers prevent long-term damage and allow quicker recovery once moisture returns.

61. ASCII table STOCKING RATE CALCULATIONS Pasture: _______________________________ Date: ________________ Acres: _______________________________ MLRA: ________________ (See Figure 1) Grazing System: ______________________________________________________ +----------------------+-----------+------+------------------+-----------+--------+ | Class of Animal | # of Head | AUE | Animal Units (AU)| Month (M) | AUMs | +----------------------+-----------+------+------------------+-----------+--------+ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +----------------------+-----------+------+------------------+-----------+--------+ | TOTAL | | | | | | +----------------------+-----------+------+------------------+-----------+--------+ Formulas: AU = # of Head × AUE (Table 1) AUM = AU × Months Notes: ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________

62. Carrying Capacity Calculations( Using estimated AUMs/ac Stocking Rates CARRYING CAPACITY CALCULATIONS Using Estimated AUMs/ac Stocking Rates Pasture: _____________________________ Date: ______________________ Acres: _____________________________ MLRA: ______________________ (See Figure 1) Grazing System: _________________________________________________________ +------------------------------+-------------------+----------+----------+ | Site Type / Vegetation Type | Acres | AUM/ac | AUM | +------------------------------+-------------------+----------+----------+ | Upland – Loamy | | | | | Upland – Sandy | | | | | Upland – Clayey | | | | | Upland – Shallow | | | | | Upland – Very Shallow/Thin | | | | | Lowland – Overflow | | | | | Lowland – Wet Meadow | | | | +------------------------------+-------------------+----------+----------+ | **TOTAL** | | | | +------------------------------+-------------------+----------+----------+ % Harvest Efficiency: _______________________________ Available AUMs: ____________________________________ Total AUM/ac: ______________________________________ Total ac/AUM: ______________________________________ Formulas: Acres × AUM/ac (Table 3) = Total AUMs/ac (given a 25% harvest efficiency) Total AUMs/ac × Harvest Efficiency Multiplier (Table 2) = Total AUMs/ac Total AUMs/ac ÷ AUE (or average AUE) = AUEM/ac (estimated # of head per acre) 1 ÷ AUEM/ac = ac/AUEM (acres needed per head per month) Notes: ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________

63. Carrying Capacity Calculations Using Production CARRYING CAPACITY CALCULATIONS Using Production Pasture: _____________________________ Date: ______________________ Acres: _____________________________ MLRA: ______________________ (See Figure 1) Grazing System: _________________________________________________________ +------------------------------+-------------------+-------------------------+-------------------+ | Site Type / Vegetation Type | Acres | RV or Actual ( lb /ac) | Production ( lbs ) | +------------------------------+-------------------+-------------------------+-------------------+ | Upland – Loamy | | | | | Upland – Sandy | | | | | Upland – Clayey | | | | | Upland – Shallow | | | | | Upland – Very Shallow/Thin | | | | | Lowland – Overflow | | | | | Lowland – Wet Meadow | | | | +------------------------------+-------------------+-------------------------+-------------------+ | **TOTAL PRODUCTION** | | | | +------------------------------+-------------------+-------------------------+-------------------+ % Harvest Efficiency: _______________________________ Total AUMs: ________________________________________ AUM/ac: ____________________________________________ ac/AUM: ____________________________________________ Formulas: Acres × RV (Table 4) or Actual Production = Total Production ( lbs ) Total Production × % Harvest Efficiency (Table 2) = Total Available Forage ( lbs ) Total Available Forage ÷ 913 lbs = AUMs AUMs ÷ Acres in Pasture = AUMs/ac OR Acres ÷ AUMs = ac/AUM AUMs/ac ÷ AUE (or avg. AUE) = AUEM/ac (head per acre) 1 ÷ AUEM/ac = ac/AUEM (acres per head per month) Notes: ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________