Grazing Corn Stalk Residue With Beef
Cows
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
Determining Ear-Drop
• 8 inch ear of corn:– Contains 0.5 lb of
grain– 112 - 8” 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
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
Composition of Corn Crop Residue
Percent DM
% CP - Range
% CP - Average
% TDN - Range
% TDN - Average
Grain 73 9.5-11.2 10.2 88-95 90
Leaf 76 6.2-7.5 7.0 41-65 58
Husk 55 3.0-4.0 3.5 63-72 68
Cob 58 2.1-3.8 2.8 59-65 60
Stalk 31 3.0-5.1 2.7 45-60 51
Dry Matter Distribution in Corn Residue
Corn Residue % Moisture % of Residue (D.M. Basis)
Stalk 70-75 50
Leaf 20-25 20
Cob 50-55 20
Husk 45-50 10
Composition of Milo Residue
Percent DM
% CP - Range
% CP - Averag
e
% TDN –
Range
% TDN -
Average
Grain 74 10.3-11.0 10.5 85-95 90
Leaf 66 6.0-13.0 10.0 40-65 57
Stalk 25 3.3-3.9 3.6 53-58 53
Composition of Soybean Residue
Percent DM
% CP-Range
% CP- Averag
e
% TDN –
Range
% TDN- Averag
e
Leaf 87 11.0-13.1
12 36-40 38
Stem 88 3.6-4.5 4.0 33-36 35
Pod 88 4.5-9.0 6.1 43-51 44
Bean 89 35-42 38.0 91-94 92
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
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] + 429 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)
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.
Cornstalk Grazing Calculator
Supplementation Strategies for Cows Grazing Corn Stalk – Whole Field
Grazing
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Cow RequirementGrain
Husk and Leaf
Cob and Stalk
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
Supplementation Strategies for Heifers Grazing Corn Stalk – Whole
Field Grazing
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October 22 March 22
Cow RequirementGrain
Husk and Leaf
Cob and Stalk
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- Need protein and energy- 0.80 lb of protein –deficient- 2.4 lb/hd/da TDN -deficient
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-valueOct. Wt, lb 1279 1282 0.81Feb. Wt, lb 1342 1333 0.41Change , Oct. - Feb., lb 63 51 0.01BCS, Oct. 5.5 5.5 0.59BCS, Feb. 5.8 5.5 0.001Change in BCS, Oct. - Feb. 0.3 0.0 0.001
Cow pregnancy rate, % 92.0 95.0 0.28Calving interval, d 365 365 0.70
Calf birth wt, lb 87 87 0.83Calf weaning wt, lba 547 548 0.86aCalf weaning weight adjusted for age of dam, age of calf, and calf sex.
(Hall et al., 2008)
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
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
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
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
Grazing Genetic Modified Corn
• Bt-corn (corn root worm protected) and RR hybrids:– Grazed with spring-calving cows
• No effect on cow performance
Questions