Cornstalk grazing is a good option during late gestation
Cornstalk residue is a good source of nutrition for the beef cow.
When grazing cornstalks, producers want to use about 15 percent of the residue. This 15 percent includes any remaining corn and 50 percent of the husk and leaf. Those parts are the most palatable and the highest quality nutrition for the cow.
For every bushel of dry corn, the husk makes up three pounds per bushel, and the leaf makes up 14 pounds per bushel. The highest nutrition out in the field is the corn that was left.
Calculation
A cow’s intake and diet quality decrease the longer she is left in the field.
When cattle graze corn residue, they select corn first, husk and leaf second and cob and stalk last. When cows are forced to eat cob and stalk, they can’t meet their nutritional needs.
A general rule of thumb is for every 100 bushels of dry corn produced, a cow can graze for one month.
To calculate how much feed is available in each field producers can use the cornstalk grazing calculator found at cap.unl.edu/livestock/tools/.
However, in recent studies, the University of Nebraska-Lincoln (UNL) has found high-yielding corn – 200 bushels per acre or greater – has less leaf and husk per bushel and the quality is generally lower than lower-yielding fields.
Based on this research, it is suggested to reduce grazing days by five percent in higher-yielding corn hybrids. This can be accomplished by changing the utilization rate to 45 percent instead of 50 percent in the grazing calculator.
Supplementation
When grazing corn residue properly, pregnant cows can meet their energy and protein needs without supplementation. However, they do require supplementation of minerals and vitamin A.
UNL personnel suggests using a four-ounce, free-choice mineral containing at least 300,000 international units per pound of vitamin A, four to five percent phosphorus, 1,500 to 2,500 parts per million copper and 3,000 to 5,000 parts per million zinc.
Corn residue, especially the husk, is susceptible to losses from trampling and wind.
Monitoring husk availability is a great way to ensure cows are receiving the nutrients they need.
When the husk is hard to find, either move cows to a new field or start feeding a supplement.
Bred and first-calf heifers have higher energy and protein requirements and need to be supplemented.
During mid gestation, two to three pounds of dried distillers’ grains or four to six pounds of modified distillers’ grains per day will meet their needs.
During late gestation, three to five pounds of dried distillers’ grains or six to 10 pounds of modified distillers’ grains per day will be sufficient.
Conclusion
In conclusion, if yield is high – around 200 to 250 bushels – cut back to 45 percent utilization.
Monitor availability of husk in the field as a way to gauge utilization.
Heifers require supplementation with a protein and energy source.
All cattle need access to a mineral source with vitamin A.
If cows are losing weight, supplement or move to another field.
Randy Saner is a UNL Extension educator and Mary Drewnoski is the UNL Extension beef systems specialist. This article was originally published in UNL Beef on Jan. 1.
