Just had read an article in Lancaster Farming about drought grown corn, here it is hope it helps.
Drought Creates Forage Management Challenges
Submitted by Editor on Fri, 08/17/2007 - 8:31am.VIRGINIA ISHLER
Penn State Dairy Alliance UNIVERSITY PARK, Pa. — Dairy producers will be dealing with the ramifications of the drought for many months to come. The short-term issue will be following the basic management practices related to potential nitrate levels in corn silage. The long-term issues will be managing the quantity and quality of forage available. As corn silage harvesting draws near, don’t forget that to reduce nitrate levels in drought-stressed plants, harvest crops in the afternoon on a warm sunny day. It is recommended to wait three to five days after an appreciable rain or long cloudy spell. Since nitrates accumulate in the stalks, the crop may be cut somewhat higher above the ground than usual. The typical recommendation is to leave 10 to 12 inches in the field. However a lot of corn is very short this year, so an adjustment to this recommendation may be needed. If in doubt, consult with cooperative extension, your crop adviser or nutritionist. If high nitrate levels are suspected, use forage as silage rather than green-chop. Ensiling reduces nitrates by 50 to 60 percent. Ideally, allow the forage to ferment for three to four weeks before feeding to allow the fermentation process to complete. Any suspect feed should be tested for nitrate levels. The most critical factor influencing possible toxicity is rate of nitrogen (N) 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 (NO3) forages. When stored forages contain more than 1,000 ppm (parts per million) 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. Protein levels in drought corn silage can sometimes be elevated and energy values 80 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. In the hardest hit areas of the state, the corn never did develop an ear or if it did, it had poor ear fill. This means that 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. In herds feeding a heavy corn silage diet, the main concern for nutritionists is how the nutrients got partitioned in the plant. A potential scenario is where the corn silage contains stover sugars and more digestible fiber compared to typical corn silage that contains starch. The nutritionist will need to complement this unique mix of sugars/starch/fiber in the ration with appropriate feed sources. Whenever possible, starch, sugar, and lignin should be included in the corn silage analysis. Because this has been an atypical growing season, check on how the energy values are being calculated and scrutinize them carefully before using them in a ration formulation program. 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.
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