# Grazing Corn Stalk Residue With Beef Cows

## Presentation on theme: "Grazing Corn Stalk Residue With Beef Cows"— Presentation transcript:

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
” 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 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

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

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

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

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] 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
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

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

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)

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