Alternate forages and supplementation
August 28, 2007
Thankfully, much of the range county has received considerable moisture this summer, and the pastures are in great shape. Unfortunately, this has not been the case in the northern Nebraska panhandle, western South Dakota, and much of Wyoming and Montana.
This has prompted many to ask about harvesting or grazing drought stressed dry land crops, such as corn, sorghum sudan crosses, forage millets, and other crops. Ultimately, the question comes to “what is its value?” This is very difficult to answer without an analysis, which is not very practical when the crop is standing in the field.
Considerable calls have been coming in concerning standing corn that is not going to produce enough grain to be cost effective to harvest. This can be grazed with good performance, but often fencing and available water is a problem. It can be harvested for corn silage and make excellent feed; however, the yield of silage is relatively low and may not be economical, especially if relying on custom harvesters.
Yields can be as low as 5-10 ton per acre, providing only 2-3 ton of equivalent dry feed. Corn that has developed well (5-6 feet tall) with plant population of around 18,000-20,000 plants per acre may yield up to 15 tons per acre. As far as feeding value is concerned, the energy value will be approximately 75-90 percent of the level of good corn silage on an equivalent dry basis, if cut while green. Good corn silage, which will have about 40 percent grain or would have made 125-150 bushels of grain per acre, will have a TDN value of around 70 percent.
Drought damaged or immature dry land corn will usually be higher in protein (1-2 percent higher), but will have a TDN value of 53-63 percent, depending on stage of harvest and amount of corn present. Corn with few or no ears will have about the same value as forage sorghum crosses if they are harvested in the milk stage or before reaching full maturity.
Some want to price dry land crops on an acre basis. This requires a considerable amount of estimating, as one must first estimate dry matter yield plus nutrition value. It is usually easier to determine value on a ton basis.
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As has been pointed out, nitrates should always be a concern and forages should be tested. If unsiled, about 50 percent of the nitrates are destroyed, which will make it a safer feed; however, it still should be analyzed in most cases before feeding. If the crop is priced as green chop, to either be fed fresh or unsiled, its value should be based on standard moisture content. Often 33-35 percent dry matter is used as a base. Failure to correct for dry matter can change the read dry value up to 33 percent and unless agreed upon up front, it often leads to lawyers getting involved.
Some people prefer to graze standing corn, and if water and fencing are available or can be temporarily built, this may be the best alternative. If the corn is relatively tall and mature, less waste will be encountered if strip grazed. Allow enough forage for 4-7 days and then move the fence. This is labor intensive, but reduces waste considerably.
I have made some rough estimates that 20-25 percent waste may be experienced if strip grazed, depending on the corn’s maturity and stalk size. If strip grazing is not utilized, waste may be slightly higher, but perhaps a bigger factor is the performance will decrease as the grazing progresses because they will graze out the part of the plant that is the highest quality first, and the lowest quality last. When grazing, nitrates are always a concern with drought damaged crops.
I have not heard of nitrate problems when grazing standing corn. This is due most likely to two factors. First, the cattle graze the parts of the plants that are lowest in nitrates initially, such as leaves, husks, and the upper part of the plant. Second, cattle have some ability to adapt to nitrates in feed if introduced slowly over a short period of time. This is not to say it is always safe to graze feeds high in nitrates, but some adaptation appears to occur.
Some want to harvest the corn as dry hay. Although this can make good feed, in most cases it will need to be ground and mixed and fed with other good quality feed. Feeding baled corn stalks without grinding will result in a large amount of waste. Also, the cost of baling and then grinding increases the cost of a relative low value feed.