Setting a Stocking Rate K. Launchbaugh K. Launchbaugh REM 456 - Integrated Rangeland Management

How do you set stocking rate? Balance supply with demand Four–Step Method

4-Step “Forage Demand” Method Calculate usable forage Adjust for accessibility (terrain or water) Calculate forage demand of animals Calculate stocking rate Supply Demand

4-Step, Forage Demand Method The forage demand method is used: When you have no stocking information from previous years To estimate carrying capacity in biological surveys or land appraisal When considering changes in kind or class of animals

Step 1 – Calculate Usable Supply Start with amount of biomass Wt of biomass/acre× area = total biomass supply Convert total biomass to total forage Not all biomass is forage Not all biomass should be grazed Use a “Proper Use Factor” to calculate forage Total biomass × proper use(%)= total forage supply

Step 1 – Calculate Usable Supply An Example – You manage a 1,200 acre ranch and the average production is 760 lbs/acre. The ranch is located in the intermountain bunchgrass region and based on this vegetation type, a proper use factor would be to remove up to 40% of annual biomass. What is your usable forage supply?

Step 1 – Calculate Usable Supply An Example – You manage a 1,200 acre ranch and the average production is 760 lbs/acre. The ranch is located in the intermountain bunchgrass region and based on this vegetation type, a proper use factor would be to remove up to 40% of annual biomass. What is your usable forage supply? 1,200 ac × 760 lbs/ac = 912,000 lbs of biomass × 40%= 364,800 lbs total Forage

Step 2 – Adjust for Accessibility Not all forage is available for grazing: Slope Distance from water National Range and Pasture Handbook USDA- NRCS

Step 2 – Adjust for Accessibility Adjustments for slope and distance from water are guidelines not rules. Depends on: Animal species, breed, and experience Topography and soils Season Temperature Forage moisture

Step 3 - Calculate Forage Demand of Animals Intake of animals on rangeland or pastures Horses eat about 3% of their weight/day Ruminants eat about 2.5% of body weight/day Ruminants eat 2.5 to 4.0% depending on size: Animal Weight % of weight/day 1,000-1,500 lbs 2.5 % 500-1,000 lbs 3.0 % 100-500 lbs 3.5 % < 100 lbs 4.0 % Justin Trujillo Connor White Tom Koener (USFWS)

Step 3 - Calculate Forage Demand of Animals If you know: Weight of animal Intake Factor (% of body weigh eaten per day) Number of animal How many days they graze on the range Then…. You can calculate total demand per season

Step 3 - Calculate Forage Demand of Animals For example – you manage a herd of beef cows with an average weight of 1,200 pounds and they graze on the ranch for 3 months (or 90 days). How much air-dry forage would you expect each cow to eat? 1,200 lb cow × 2.5% = 30 pounds forage eaten per day 30 pounds × 90 days = 2,700 lbs/cow/season For a herd of 55 cows: 2,700 lbs × 55 = 148,500 lbs demand for the whole herd

Step 3 - Calculate Forage Demand of Animals in AUMs Demand can be expressed in AUMS: AUM= 750 lbs which is 1,000 lbs grazing ruminant × 2.5% to get lbs/day of intake × 30 days in a month AUE = Animal Unit Equivalent = the proportion of an animal unit that each animal is equivalent to.

Step 3 - Calculate Forage Demand of Animals in AUMs Number of Animals × the AUE for that species and type = AUs For example, 6 bulls × 1.35 = 8.1 AU 270 goats × 0.15 AUE = 40.5 AU 100 elk × 0.6 AUE = 60 AU National Range and Pasture Handbook USDA- NRCS

Step 3 - Calculate Forage Demand of Animals in AUMs Calculate number of AUs: Number of animals× AUE = AU Calculate number of AUMs: AU × number of months grazing= AUMs For Example - Horses that graze for 6 months Horse× 1.25 AUE × 6 months = 7.5 AUMs Express in pounds, if desired: 7.5 AUMs × 750 lbs = 5,625 lbs

Step 4 - Calculate Stocking Rate A stocking rate must include: Number of animals or animal units Specified area (acres, hectare, pasture, or ranch) Specified time (days, months, or season) The following are stocking rates because they include all 3 of the necessary elements: Ac/AUM or AUM/Ac 15 cows/35 acre pasture/4 months Flock of 450 ewes and lambs on ranch for a year

4-Step “Forage Demand” Method Calculate usable forage Adjust for accessibility (terrain or water) Calculate forage demand of animals Calculate stocking rate Supply Demand

Variable/Flexible vs Fixed Stocking Amount of forage varies from year to year long-term average Sharp, L. A., K. Sanders, & N. Rimbey. (1992). Variability of crested wheatgrass production over 35 years. Rangelands. 14:153-168.

How do you set a stocking rate amidst variability? 1957 Precipitation = 11.7” Grass Production = 846 lb/ac 1959 Precipitation = 11” Grass Production = 416 lbs/ac How do you set a stocking rate amidst variability? 1960 Precipitation = 6.5” Grass Production = 186 lbs/ac 1971 Precipitation = 16.2” Grass Production = 1090 lbs/ac Sharp, L. A., K. Sanders, & N. Rimbey. (1992). Variability of crested wheatgrass production over 35 years. Rangelands. 14:153-168.

Variable/Flexible vs Fixed Stocking Amount of forage varies from year to year long-term average Flexible - no more than 60% of herd in breeding stock Fixed- herd size that could be sustained if rainfall was 25% below average.

Establish stocking rate based on: Past experience Current situation Long-range weather forecast Financial goals Etc. NRCS USDA

Setting a Stocking Rate K. Launchbaugh K. Launchbaugh REM 456 - Integrated Rangeland Management

Set a Stocking Rate and Then Monitor! With this method stocking rate is determined by trial and error over years and then monitored by: Range Trend = changes in plant composition or rangeland health over time

Monitoring Approaches Key Species = a species that indicates use of associated species Abundant Productive Palatable, but not an “ice cream” plant Provides bulk of forage for grazing animals Key Area = portion of range which because of location, vegetation community or topography is a used as an indicator of the whole pasture. Not too remote from water (within 3/4 mile) Accessible to livestock No topographic limitations More than 50 acres.

Grazing Capacity Summary Use caution when estimating grazing capacity Combine Utilization measurements Interpretation of current range condition Knowledge of past and present stocking Monitor! Adjust as needed