Transcript Plant_Science_files/Stocking Rate Lesson

Stocking Rate
Terms
 Animal Unit (AU) - equivalent to a 1,000lb cow
 1000lb = 1.0 AU
- 1200lb = 1.2 AU
 Animal Unit Month (AUM) - amount of forage
eaten by 1 AU in 1 month
 1 AUM = 780lb fry forage
 Animal Unit Day (AUD) - amount of forage
eaten by 1 AU in 1 day
 1 AUD = 26 lb dry forage
AUM’s Available
 Studies have found the average AUM’s
produced per acre by different range sites
based on range condition.
 Example: Sandy in excellent condition = 0.9
AUM/acre; Sandy in Good Condition = 0.7 AUM/acre
 Available AUM’s = # Acres X AUM’s / Acre
 200 acres of Sandy in excellent condition would be:
200 acres X 0.9 AUM/acre = 180 AUM’s available
 Landowner may wish to save a % for wildlife
AUM’s Available Examples
 200 acres Sandy in excellent condition (0.9)
Aum/acre
 200 X 0.9 = 180 AUM available
 320 acres Silty in good condition (1.2
AUM/acre and 160 Silty Overflow in excellent
condition (1.6 AUM/acre)
 320 X 1.2 = 384 AUM’s
 160 X 1.6 = 256 AUM’s
 384 + 256 = 640 AUM’s Available
AUM’s Available Examples
 200 acres Sands in good condition (0.7
AUM/acres) and 400 acres Choppy Sands in
excellent condition (0.6 AUM/acre) The
landowner wishes to save 10% of forage for
wildlife
 200 X 0.7 = 140 AUM’s
 400 X 0.6 = 240 AUM’s
 140 + 240 = 380 AUM’s X 10% = 38 AUM’s
 380 - 38 = 342 AUM’s Available
AUM’s Needed
 AUM’s needed = #head X AU/head X months
 Grazing 200 cows (1.2 AU/cow) from May 1 to
October 1 and 10 bulls (1.6 AU/bull) from May
1 to July 15
 200 X 1.2 X 5 = 1200 AUM’s
 10 X 1.6 X 2.5 = 40 AUM’s
 1200 + 40 = 1240 AUM’s needed
Stocking Rate Check
 Stocking rate (number of animals grazing)
should be changed if the difference between
AUM’s available and AUM’s needed is greater
than 10% of AUM’s available
 Increase stocking rate if there are more AUM’s
available than needed
 Decrease stocking rate if there are more AUM’s
needed than available
Stocking Rate Check Example
 320 acres Sandy in good condition (0.7
AUM/acre) and 180 acres Sands in excellent
condition (0.9 AUM/acre) Grazing 50 cows
(1.3 AU/cow) from May 15 to October 15 and
2 bulls (1.5 AU/bull) from June 1 to August 1
 320 X 0.7 = 224
180 X 0.9 = 162
 224 + 162 = 386 AUM’s Available
 50 X 1.3 X 5 = 325
2 X 1.5 X 2 = 6
 325 + 6 = 331 AUM’s needed
 386 - 331 = 55 AUM’s difference
 Increase Stocking Rate
Stocking Rate Check Example
 1000 acres Silty in excellent condition (1.5
AUM/acre) Grazing 285 cows (1.2 AU/cow)
from May 1 to September 1. The landowner
wishes to save 15% of forage for wildlife.
 1000 X 1.5 = 1500 X 15% = 225
 1500 - 225 = 1275 AUM’s Available
 285 X 1.2 X 4 = 1368 AUM’s needed
 1368 - 1275 = 93 AUM’s difference
 No change needed in stocking rate