Dairy producers that reside in drought-stricken areas will be dealing with the ramifications of the drought on forage production for many months to come. The short-term issue will be following the basic management practices to reduce the potential nitrate levels in corn silage. The long-term issues will be managing the quantity and quality of forage available.
Experts with the Penn State Dairy Alliance program offer the following suggestions for harvesting and feeding drought-stressed corn for silage:
- Harvest in the afternoon on a warm sunny day. This will help reduce nitrate levels.
- Wait three to five days after an appreciable rain or long cloudy spell to harvest.
- Nitrates accumulate in the stalks, so cut higher above the ground than usual. The typical recommendation is to leave 10 to 12 inches in the field.
- If high nitrate levels are suspected, use forage as silage rather than green-chop. Ensiling reduces nitrates by 50 to 60 percent.
- Allow the forage to ferment for three to four weeks before feeding to allow the fermentation process to complete.
- Test any suspect feed for nitrate levels. The most critical factor influencing possible toxicity is rate of nitrogen intake, which is affected by forage dry matter intake over a given time period. Feeding practices that regulate dry matter intake can be used to manage high nitrate forages. When stored forages contain more than 1,000 ppm NO3-N, intakes generally must be managed to avoid elevated methemoglobin levels in the blood and other toxic effects.
The long-term concern with corn silage will be the extreme variation in quality. This will present nutritionists with many challenges. This year’s drought conditions will result in reduced yields and the nutritive content will not be consistent or typical. Here are a few things to keep in mind:
- Protein levels in drought corn silage can sometimes be elevated.
- Energy values are often 80 percent to 100 percent of normal depending on the fiber level.
- It is not uncommon to see both high and low fiber levels during drought years.
- If the corn did develop an ear, or had poor ear fill due to drought, the energy of the plant is in the form of sugar, which is found in the stover and leaves. This can dilute the neutral detergent fiber content but not yield the expected net energy associated with corn silage that contain normal grain yields.
The second long term issue is the reduced tonnage of corn silage harvested. Now is the time to plan out inventory and evaluate various feeding strategies. Consult with your nutritionists on alternative forage and feed sources and evaluate the impact on income over feed costs. The key to feeding drought-stressed forages over the next months is to work closely with a good nutritionist. They can help monitor forage inventory, quality changes in forages, and most of all, keep cows milking.