Stocking rate on corn residue is extremely important because it affects the animal’s plane of nutrition. When grazing corn residue, cattle select dropped corn grain along with the husks and leaves. Digestibility or energy available from the diet is quite high at the initiation of grazing, but declines with time because cattle select the more digestible parts such as grain and husk early in the grazing period. The corn grain itself has more energy (83% TDN) and protein (9% CP) than any other plant part. Husk is about 60% TDN and leaf is about 50% TDN. Cattle consume cob and upper stalk (which are low energy; 35% TDN) only when availability of husk and leaf is limiting.
This information has been the basis of stocking rate recommendations (remember other losses will occur such as wind and trampling loss). The general rule of thumb is that corn residue can be stocked at 1 cow (1200 lb) for one month for every 100 bu of corn (Table 1). At this stocking rate, cattle would be consuming 50% of the leaf and husk available which is only 15% of the total corn residue produced.
Grazing Calculations
| Corn Yield, bu/ac | Animal Unit Month1 (AUM)/ac | # of grazing days at one 1200 lb cow/ac |
| 100 | 1.1 | 28 |
| 125 | 1.4 | 36 |
| 150 | 1.7 | 43 |
| 175 | 2 | 50 |
| 200 | 2.3 | 57 |
| 225 | 2.6 | 64 |
| 250 | 2.8 | 71 |
| 1One Animal Unit Month (AUM) is the amount of forage required to sustain a 1,000 pound cow or equivalent for one month | ||
Stocking density can be used to influence an animal’s plane of nutrition. Some producers use a higher stocking density and a shorter amount of time and move cows from field to field over the winter. With this type of grazing, the plane of nutrition cycles with nutrition being greatest at the start of a new field and then declining until they start in a new field again. This allows producers to provide a more nutrient-dense diet in late winter when spring calving cow’s requirements are greater. Although there is a nutritional benefit to this strategy, there is also the risk of winter weather such as ice restricting grazing such that the cattle must be removed from residue grazing, resulting in some fields not being grazed and thus the highest quality components in those fields not being used.
Do you want to calculate how long you can graze, given the yield, acres, and number of cows you have? Then check out the Excel based Corn Stalk Grazing Calculator. It can also be used to calculate the cost when accounting for rental rates, hauling of cattle, and other labor.
For more on this topic, explore the related YouTube video: Grazing Corn Residue with Cattle: common nutrition questions answered.
Grazing Capacity: A Starting Point
The standard rule of thumb for estimating corn residue grazing capacity is: 100 bu of grain yield = 30 grazing days for a 1,000-lb animal. While the actual amount of grazing will vary from field to field, this rule of thumb can be used to estimate a recommended maximum amount of grazing.
You can use the following to estimate the amount of grazing available in a field:
Tips and Takaways
Consider Adjusting Grazing Utilization Based on Quality
Cattle prefer husks and eat them first. Husk also has the most energy. As they continue grazing a field, their intake shifts toward leaf material, which is lower in energy. At the same time, total forage intake tends to decline due to increased time spent selectively grazing.
If your forage test results show:
- Leaf TDN is low (e.g., 42–50%): You may need to supplement energy later in the grazing period or move cows earlier to a new field, rather than grazing down to the recommended utilization rate.
- Leaf TDN is high (e.g., >50%): The field likely has enough energy to meet the needs of mature cows without energy/protein supplementation, as long as you follow the recommended utilization rates.
Matching Fields to Cattle Groups
If you're managing multiple fields and different groups of cattle, the energy content can help you match the right field to the right group:
- Higher-energy fields (e.g., high husk TDN) could be reserved for: growing calves, including replacement heifers, first-calf heifers and/or thin cows.
- Lower-energy fields may still work for mature cows in good condition even without supplementation, especially if grazing time is limited and early in the winter when requirements are lowest (i.e. mid gestation).
Regardless of energy content, young cows, heifers, and growing calves will still require protein supplementation. Corn residue is low in protein, so plan to provide a protein source (e.g., distillers) to meet their requirements. However, despite corn residue being low in protein if the energy content is good (i.e. husk and leaf is in the moderate to high range), mature cows can meet their protein needs due to their ability to recycle nitrogen.
Takeaways
Corn residue is a valuable and cost-effective feed resource, but its quality is variable. Forage test results and the estimates provided in this tool can be used to guide management. By testing your husk and leaf separately and using our custom equations, you can better match field conditions to cattle needs. Supplementation decisions, stocking rate, and expected performance can all be fine-tuned using this information.