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 ResiduePercent 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

eLeaf 87 11.0-

13.112 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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October 22 March 22

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