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Topics : Pastures : Determining Pasture Yield

Determining Pasture Yield

Additional pasture information via the Forage Information System (FIS)


Examples of Pasture Yield Calculations

To estimate how much forage is consumed by the grazing animals you need to estimate the DM before and after each grazing event. The subtraction of pre-grazing DM minus post-grazing DM will be the actual forage consumed.

 

 

Using Pasture Ruler

Pre-Grazing Post-Grazing

Sample Number

Plant Height (in)

1

5

2

10

3

12

4

7

5

6

6

11

7

13

8

9

9

6.5

10

9

11

10

12

8

13

11

14

7

15

12

16

13

17

7.5

18

9

19

5.5

20

9

Sum = 180.5 in

Average height = 180.5/20= 9.025

Pre-grazing yield = 9.0*300 lb DM//in/A
Pre-grazing yield = 2700 lb DM//A

Sample Number

Plant Height (in)

1

1.5

2

2

3

5

4

3

5

2

6

3

7

3.5

8

2

9

1.5

10

2

11

2.5

12

1

13

3.5

14

2

15

3

16

4

17

2

18

1.5

19

1

20

2

Sum = 48 in

Average height = 48/20= 2.4

Post-grazing yield = 2.4*300 lb DM//in/A
Post-grazing yield = 720 lb DM//A

 

Total forage consumed = Pre-grazing DM – Post-grazing DM
Total forage consumed = 2700 lb DM/A - 720 lb DM/A = 1980 lb DM/A
Thus during this grazing event 1980 lb DM/A were consumed.

 


Using Rising Plate Meter

 

Pre-grazing

Post-Grazing

Initial plate meter

57893

60245

Final plate meter

58943

60670

Counter

25

25

Final – Initial

58943 - 57893 = 1050

60670 – 60245 = 425

Average RPM

1050/25 = 42

425/25=17

Yield†

42*69 - 560 = 2338 lb DM/A

17*69 - 560 = 613 lb DM/A

†This equation was developed for grass based pastures (less than 30% legumes).

Total forage consumed = Pre-grazing DM – Post-grazing DM
Total forage consumed = 2338 lb DM/A - 613 lb DM/A = 1725 lb DM/A
Thus during this grazing event 1725 lb DM/A were consumed.