Grazing Corn Stalk Residue With Beef Cows

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 • 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

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

6. Dry Matter Distribution in Corn Residue

7. Composition of Milo Residue

8. Composition of Soybean Residue

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] + 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)

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 Husk and Leaf Percent Crude Protein 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 • Need protein and energy • 0.80 lb of protein –deficient • 2.4 lb/hd/da TDN -deficient Cow Requirement Grain Husk and Leaf Percent Crude Protein 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 1279 1282 0.81 Feb. Wt, lb 1342 1333 0.41 Change , Oct. - Feb., lb 63 51 0.01 BCS, Oct. 5.5 5.5 0.59 BCS, Feb. 5.8 5.5 0.001 Change in BCS, Oct. - Feb. 0.3 0.0 0.001 Cow pregnancy rate, % 92.0 95.0 0.28 Calving interval, d 365 365 0.70 Calf birth wt, lb 87 87 0.83 Calf weaning wt, lba 547 548 0.86 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