1. Grazing Corn Stalk Residue With Beef Cows

2. Presentation: Determining the amount of ear-drop
Nutrient quality of crop residues
Determining the stocking rate of corn stalk residue
Supplementation strategies
Protein and energy
Grazing strategies
Effect of grazing on subsequent crop yield

3. Determining Ear-Drop 8 inch ear of corn: Contains 0.5 lb of grain
” ears yield one bushel (56 lb per bushel) of corn
6” ear = 2/3 of an 8” ear
4 inch ear = ½ of an 8” ear
12” ears = 1 ½ of an 8” ear

4. Determining Ear-Drop
In a 30” wide row Count the number of 8” inch ear equivalents in 3 different 100 foot long strips.
Divide the number of ears by 2 to get approximate bushel per acre.
Example:
Count #1 – 2 - 8” ear equivalents
Count # 2 – 1 ½ - 8” ears equivalents
Count #3 – 1 – 8” ear equivalents
2 + 1 ½ + 1 = 4 ½ 8” ear equivalents
4 ½ / 2 = 2 ¼ bushel per acre

5. Composition of Corn Crop Residue
Percent DM
% CP - Range
% CP - Average
% TDN - Range
% TDN - Average
Grain 73
10.2
88-95 90
Leaf 76
7.0
41-65 58
Husk 55
3.5
63-72 68
Cob
2.8
59-65 60
Stalk 31
2.7
45-60 51

6. Dry Matter Distribution in Corn Residue
% Moisture
% of Residue (D.M. Basis)
Stalk
70-75 50
Leaf
20-25 20
Cob
50-55
Husk
45-50 10

7. Composition of Milo Residue
Percent DM
% CP - Range
% CP - Average
% TDN – Range
% TDN - Average
Grain 74
10.5
85-95 90
Leaf 66
10.0
40-65 57
Stalk 25
3.6
53-58 53

8. Composition of Soybean Residue
Percent DM
% CP-Range
% CP- Average
% TDN – Range
% TDN- Average
Leaf 87 12
36-40 38
Stem 88
4.0
33-36 35
Pod
6.1
43-51 44
Bean 89
35-42
38.0
91-94 92

9. Grazing Characteristics of Cows on Corn Stalks
Cows are “selective” grazers on stalk fields
Select the corn first – Diet quality selected = high
Select husk and leaves second – Diet quality = medium
Select cob and stalk last – Diet quality selected = low

11. Determining Stalk Rate of Corn Stalk Residue
Residue yield related to grain yield
16 lb of dry leaf and husk per bushel of corn
Pounds of husk and leaf per acre (DM)
([bu/acre corn yield x 38.2] x 0.39
150 bu/acre corn = 16 lb of l&h x 150 = 2400 lb DM/acre
Assume 50% available to graze (trampling etc losses)

12. Determining Stalk Rate of Corn Stalk Residue
Residue yield related to grain yield
2400 lb DM/acre/2 = 1200 lb of residue per acre available
1 AUM = 702 lb of DM
1200 lb cow is 1.2 AU
1.2 AU x 702 lb = 842 lb forage DM per month for 1200 lb cow
1200 lb of l&h per acre / 842 lb for 1200 lb cow = 1.47 Months
1 ac would supply enough forage for 44 days.

13. Cornstalk Grazing Calculator

14. Supplementation Strategies for Cows Grazing Corn Stalk – Whole Field Grazing
Supplementation Strategy
Spring calving cows: pre-calving
Less than 1.5 bu/acre ear drop
Recommended stocking rates
None needed 1st 30 days of grazing
Need some protein supplementation
30-40 days of grazing
0.38 lb of protein deficient
3 lb/hd/da alfalfa as is
1.75 lb/hd/da cube as is
65% DDG cube
after 50 – 60 days of grazing
Need protein and energy
0.68 lb of protein-deficient
1.9 lb of TDN-deficient
5 lb/hd/da alfalfa as is
3 lb/hd/da cube as is
Cow Requirement
Grain
Percent Crude Protein
Husk and Leaf
Cob and Stalk
October 22
March 22

15. Supplementation Strategies for Heifers Grazing Corn Stalk – Whole Field Grazing
Supplementation Strategy
Spring calving heifers: pre-calving
Less than 1.5 bu/acre ear drop
Recommended stocking rates
None needed 1st 30 days of grazing
Need supplementation
after day 30 of grazing
Need protein and energy
0.68 lb of protein-deficient
0.70 lb of TDN-deficient
5 lb/hd/da alfalfa as is
3 lb/hd/da cube as is
After day 55 of grazing
0.80 lb of protein –deficient
2.4 lb/hd/da TDN -deficient
Cow Requirement
Grain
Percent Crude Protein
Husk and Leaf
Cob and Stalk
October 22
March 22

16. Table 1. Performance of cows that were either supplemented or not supplemented with a distillers grains based cube in late gestation while grazing corn stalk residue.
SUPP CON P-value
Oct. Wt, lb
Feb. Wt, lb
Change , Oct. - Feb., lb
BCS, Oct
BCS, Feb
Change in BCS, Oct. - Feb
Cow pregnancy rate, %
Calving interval, d
Calf birth wt, lb
Calf weaning wt, lba
aCalf weaning weight adjusted for age of dam, age of calf, and calf sex.
(Hall et al., 2008)

18. Grazing Strategies for Cows Grazing Corn Stalk Residue
Whole field grazing
Most common grazing strategy used
Highest quality diet consumed early
Diet quality decreases over time – corn, husk and leaf, cob and stalk

19. Grazing Strategies for Cows Grazing Corn Stalk Residue
Strip Grazing
Not commonly used – more labor
Diet quality is higher than whole field grazing
More likely to have to haul water
Risk – if you get a lot of snow, may leave corn in the field
If ear drop is greater than 8 bu/acre – strip graze

20. Health Concerns for Cows Grazing Corn Stalk Residue
Founder
If ear drop is greater than 8 bu/acre
If combine “spills” or over-shoots transport wagon
Could add sodium bi-carbonate to water – 2.5#/100 gal
Nitrates usually not a problem
Total nitrate intake = forage(s) + water (additive)
Provide fresh water at all times

21. Effect of Cows Grazing Corn Stalk Residue on Subsequent Grain Yields
Grazed and non-grazed ridge-tilled and conventional cropping systems:
- No difference in corn grain yield
- 1 in 3 year, 8% reduction in soybean yield
- Year 3 – ground not frozen
* Concern if conditions are muddy - March

22. Grazing Genetic Modified Corn
Bt-corn (corn root worm protected) and RR hybrids:
Grazed with spring-calving cows
No effect on cow performance

23. Questions