Testing Corn Grain Helps Protect Livestock Health

By Scout Nelson

Heavy rainfall and flooding can create problems for corn growers and cattle producers. Wet conditions may affect grain quality, increase the risk of mold and mycotoxins, and reduce the value of corn residue for grazing livestock. These changes can lead to concerns about crop storage, animal health, and feed supplies. Producers can manage these risks by checking their crops, testing questionable feed, and making careful decisions before feeding grain or grazing fields.

Connor Biehler, Nebraska Extension Educator, provided information to help farmers understand how wet weather affects corn grain and crop residue. The main concerns include kernels sprouting on the ear, mold growth, possible mycotoxin contamination, and changes in the amount and quality of residue available for cattle. Not every weather-damaged crop is unsafe to use, but producers need to assess each field and feed source before deciding how to use it.

Why Corn Kernels Sprout Before Harvest

Corn kernels sometimes begin to grow while still attached to the ear. This process is called a vivipary. It can occur when extended rainfall, high humidity, and slow grain drying create conditions that allow kernels to germinate before harvest.

The problem does not affect every corn hybrid equally. Some producers report more sprouting in hybrids with upright ears because water can collect around the kernels and remain trapped for longer periods. Sprouting may be especially noticeable near the base of the ear, where water tends to gather.

Although sprouted kernels can look serious, a small amount of sprouting does not always cause a major loss in feeding value. The bigger concerns are reduced storage life, harvest losses, and a greater chance of ear and cob rot. Producers should pay close attention to grain condition and storage needs rather than assuming that all sprouted corn is unusable.

Understand the Difference Between Mold and Mycotoxins

Mold and mycotoxins are different concerns. Mold is a type of fungus that can grow on grain and plant material. Mycotoxins are harmful substances produced by certain fungi under suitable conditions.

Grain may contain mold without having dangerous levels of mycotoxins. Mycotoxins can also be present even when grain looks clean. Therefore, visual checks alone cannot confirm whether grain is safe for livestock.

The risk depends on the type and amount of mycotoxin present and the animal consuming the feed. Cattle may tolerate some contaminated feed better than swine and poultry, but tolerance varies with the animal's age, health, and production stage. Grain that is suitable for one group of animals may not be suitable for another.

Laboratory testing is the most reliable way to measure mycotoxin levels. Producers should collect a representative sample of questionable grain, ensiled corn, or residue and send it to a qualified laboratory before making feeding decisions. Test results can help determine which animals may safely receive the feed and whether limits on the amount fed are needed.

Make Careful Decisions About Damaged Grain

Weather-damaged corn may still have value as livestock feed or for certain processing markets. Depending on its condition, it may be sold as dry grain or marketed at a reduced price.

However, damaged grain may have a shorter storage life, lower palatability, and a lower market value. Grain with low mold levels may present less concern, while moderate mold growth calls for greater care. Grain with heavy mold growth may require dilution under professional guidance or may need to be excluded from animal diets.

Mold counts alone do not show whether mycotoxins are present. Testing is important when field conditions, grain appearance, or storage problems raise concerns. Producers should use laboratory results and advice from animal nutrition professionals to decide how to handle and feed damaged grain.

Wet Weather Can Reduce Corn Residue Value

Corn residue is another important feed source that can be affected by wet fall weather. Leaves and husks are often the most digestible and preferred parts of the plant for grazing cattle. However, prolonged moisture and warm temperatures can speed up residue breakdown.

Fungal diseases, including tar spot, may add to the damage in affected fields. As leaves and husks break down, both the amount of residue available and its feeding quality may decline before cattle begin grazing.

Producers should inspect each field instead of assuming that all corn residue has the same value. Fields with greater damage or decomposition may provide less feed than expected. Cattle may need different stocking rates, shorter grazing periods, or additional feed to meet their nutritional needs.

Steps Producers Can Take

Farmers and cattle producers can reduce risks by following several practical steps:

• Inspect grain: Check for sprouting, mold, and signs of ear or cob rot.
• Test questionable feed: Use laboratory analysis to measure mycotoxin levels before feeding.
• Protect stored grain: Monitor moisture and storage conditions to limit further quality loss.
• Match feed to livestock: Use test results and expert advice to select suitable animals and feeding rates.
• Evaluate residue fields: Check the amount and condition of leaves, husks, and other plant material before grazing.
• Adjust grazing plans: Change stocking rates and provide supplements when residue cannot meet cattle's needs.

Careful Assessment Protects Feed Value

Wet weather does not automatically make all corn grain or residue unusable. However, sprouting, mold, mycotoxins, and faster residue breakdown can create real challenges. Testing questionable feed, inspecting fields, and adjusting storage and grazing plans help producers protect livestock and make better use of available feed resources.

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