Frost-Damaged and Immature Corn: Management Options
Cool, wet springs, delayed falls, and early frosts often result in immature or frost-damaged corn. While these conditions reduce grain yield, they create opportunities for livestock feed production. Common options include silage, high-moisture grain, grazing and/or baling or grazing stover.
Key Considerations:
- Alternative Uses: If grain harvest is not feasible, consider selling to livestock producers or using the crop for feed.
- Decision Factors:
- Fencing availability
- Cattle trained for electric fencing
- Local demand for feed
- Pricing: Ensure competitive pricing when selling, as silage transport is costly and logistically challenging.
Silage Management
Harvest Timing:
Timing is critical for silage quality. Ideally, corn should be harvested at 55–68% plant moisture and at 1/3 to 2/3 milk line in kernels for optimal feed value. Early planting typically allows proper harvest before frost, but immature or frosted corn requires special considerations.
Timing is critical for silage quality. Ideally, corn should be harvested at 55–68% plant moisture and at 1/3 to 2/3 milk line in kernels for optimal feed value. Early planting typically allows proper harvest before frost, but immature or frosted corn requires special considerations.
After Frost:
Immediately following frost, immature corn is often too wet to chop. Delay harvest until moisture reaches the recommended range. Harvesting at excessive moisture can:
Immediately following frost, immature corn is often too wet to chop. Delay harvest until moisture reaches the recommended range. Harvesting at excessive moisture can:
- Disrupt fermentation
- Increase seepage losses
- Reduce feed intake
- Cause freezing issues in storage
Moisture Assessment:
Visual cues can be misleading—brown leaves do not indicate a dry plant. Most moisture remains in the stalk and ear. Frozen corn dries at about 0.5% per day, similar to unfrozen corn.
Visual cues can be misleading—brown leaves do not indicate a dry plant. Most moisture remains in the stalk and ear. Frozen corn dries at about 0.5% per day, similar to unfrozen corn.
Ensiling Practices:
Follow standard silage protocols for packing, covering, and particle size. Consider inoculants or preservatives if frost has killed natural fermentation bacteria. Use only research-proven products and follow label directions.
Follow standard silage protocols for packing, covering, and particle size. Consider inoculants or preservatives if frost has killed natural fermentation bacteria. Use only research-proven products and follow label directions.
Ensiling Immature Grain Corn
Harvest Timing
- Recommended grain moisture for ensiling: 25–30%
- At physiological maturity, grain moisture is typically 30–35%.
- If frost occurs before maturity, allow grain to dry before ensiling to avoid dry matter losses.
- Immature grain may require ensiling as ear corn (including cobs). In such cases, moisture can be 4–6% higher than normal recommendations.
Nutritive Value
- High-moisture corn and ear corn offer similar energy and higher crude protein than dry corn harvested before maturity.
- Higher moisture increases starch digestibility, so introduce gradually into rations.
- Processing guidelines:
- Crack 90% of kernels before ensiling.
- Break cobs into ½-inch pieces for ear corn.
- Adjust grind based on moisture:
- Higher moisture: Coarser grind to slow digestion.
- Lower moisture: Finer grind for better packing.
Test Weight Considerations
- Immature corn may have lighter test weight, but studies show corn as light as 46 lbs/bu does not affect animal performance.
- When feeding lighter grain, feed by weight, not volume.
Feed Quality Considerations
Feed quality depends on crop maturity at harvest:
- Dough stage: 65–85% of normal tonnage
- Dented stage: Good quality silage with slightly reduced yield
Immature corn typically has:
- Lower starch in kernels
- Higher sugar and lower lignin in stalks (improved digestibility)
- Slightly higher fibre and crude protein
- Slightly lower energy
Nitrate Risk:
If leaves are dead but stalks remain alive, nitrates may accumulate in the lower stalk. Raising cutting height improves quality and reduces nitrate risk but can reduce yield by ~15%.
If leaves are dead but stalks remain alive, nitrates may accumulate in the lower stalk. Raising cutting height improves quality and reduces nitrate risk but can reduce yield by ~15%.
The table shows corn silage quality at different harvest maturities, comparing five stages:
Stage of Maturity |
Yield (Ton/acre) |
Moisture (%) |
Crude Protein (%) |
NDF (%) |
ADF (%) |
Soft Dough |
5.4 |
76 |
10.3 |
52.7 |
27.2 |
Early Dent |
5.6 |
73 |
9.9 |
48.0 |
24.3 |
½ Milk Line |
6.3 |
66 |
9.2 |
45.1 |
22.8 |
¾ Milk Line |
6.4 |
63 |
8.9 |
47.3 |
23.8 |
No Milk Line |
6.3 |
60 |
8.4 |
47.3 |
24.0 |
Key Observations:
- Yield: Increases from 5.4 (Soft Dough) to 6.4 (¾ Milk Line), then stabilizes.
- Moisture: Declines steadily from 76% to 60% as maturity progresses.
- Crude Protein: Decreases from 10.3% to 8.4%.
- NDF & ADF: Both decrease initially, then rise slightly at later stages.
Best Practices
- Feed Analysis: Always test silage from frost-damaged crops. Use proper sampling (15–20 spots with a feed probe) and include pH testing to confirm fermentation.
- Consultation: Work with a nutritionist to balance rations based on analysis results.
