K Launchbaugh Setting a Stocking Rate REM 456
K. Launchbaugh Setting a Stocking Rate REM 456 - Integrated Rangeland Management
How do you set stocking rate? Balance supply with demand Four–Step Method
4 -Step “Forage Demand” Method 1. Calculate usable forage 2. Adjust for accessibility (terrain or water) 3. Calculate forage demand of animals 4. 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 Justin Trujillo § Ruminants eat 2. 5 to 4. 0% depending on size: Animal Weight 1, 000 -1, 500 lbs 500 -1, 000 lbs 100 -500 lbs < 100 lbs % of weight/day 2. 5 % 3. 0 % 3. 5 % 4. 0 % 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: 1. Number of animals or animal units 2. Specified area (acres, hectare, pasture, or ranch) 3. 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 1. Calculate usable forage 2. Adjust for accessibility (terrain or water) 3. Calculate forage demand of animals 4. Calculate stocking rate Supply Demand
Variable/Flexible vs Fixed Stocking n 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.
1957 Precipitation = 11. 7” Grass Production = 846 lb/ac 1959 Precipitation = 11” Grass Production = 416 lbs/ac ? y t i l i riab a v t s mid 1960 t s a set Precipitation = 6. 5” u o y Grass Production w do = 186 lbs/ac Ho a e t a r g n i k oc 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 n Amount of forage varies from year to year long-term average n Flexible - no more than 60% of herd in breeding stock Fixed- herd size that could be sustained if rainfall was 25% below average. n
Establish stocking rate based on: § § § Past experience Current situation Long-range weather forecast Financial goals Etc. NRCS USDA
K. Launchbaugh Setting a Stocking Rate 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
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