STRAIGHT FROM THE HORSES MOUTH

Duane A. Lienemann,
 UNL Extension Educator,
Webster County
September 28, 2012 Edition

I have spent a lot of time this past several months complaining about the drought, and for good reason. The drought this year has left many cattle producers in an awful bind. If you have priced hay you know that prices are high and pastures were pretty much history a couple of months ago leaving no option but to do things like early weaning, culling open, old or unproductive cows and even those cows that look to be calving later than the others. I know that a lot of producers have been creep feeding calves and supplementing pastures with hay and even mixed forages with grain or corn ethanol byproduct. I know a lot of cattle producers who have been waiting, somewhat impatiently, for the corn to be harvested as they know that corn stalks are an excellent grazing option. The use of corn residue offers producers increased flexibility for fall and winter pasture and helps reduce the overall feed costs. While many producers annually graze cornstalks, this year it will be of even more importance. Some cattle are already in stalks and some corn fields are even being baled for feed.
Corn Stalk Grazing: Grazing corn residue can be an important part of many livestock operations. One acre of corn residue can supply enough forage to sustain a 1,000-pound cow or animal equivalent for 1.5 to 2 months. It is estimated that for each bushel of shelled corn produced per acre, 50 pounds of residue are also produced. At that level, an acre yielding 120 bushels of corn will produce 6,000 pounds of residue. An added benefit for grazers is that corn grain is also lost in the harvesting process. It is estimated that at least three bushels of grain per acre are left on the field during harvest. This means that more than 150 pounds of corn per acre are also available for the animals to consume. About 50 percent of the weight of the total corn plant is residue left after harvest. This residue consists of stalk, leaf, cob, and husk. With the stalk supplying 50% of the reside, you will find that leaves only supply 20% and it may surprise you that another 20% is the cob, leaving the husks at 10%. For best utilization, - corn fields should be used immediately after harvest for 30 to 60 days to take maximum advantage of the feed value of the residue. This would allow the permanent pastures to "stockpile" additional days of fall growth that could be grazed after the animals come off the corn fields. Grazing corn fields for an extended period, even all winter, is also an option if supplemental feed is provided and the fields remain dry.
It should not surprise you that livestock will selectively graze the most palatable portions of the residue first, just like they will in a pasture, starting with the grain, leaves, and husks and then the cobs and stalks. Generally, animal grazing will leave 75 to 80% of total residue in the field, especially if animals are rotated to new areas before much of the cob and stalk material is consumed. With this in mind, one acre of corn residue will yield approximately 60 animal-unit grazing days. This means that one acre of corn residue will provide 60 days of grazing for a 1,000-pound animal.
I suggest if you have the resources and time that limiting access by strip grazing will allow for an increased stocking rate and greater utilization of the residue. This can be accomplished by using portable electric fencing. Either a single break wire to the front, or double wires with one in front and one to follow can be used effectively, depending on the layout of the field and water sources. However, if strip-grazing practices are used, and snow cover arrives before the field is grazed through, some of the best feed may be lost if the grain and husks cannot be recovered.
Be Careful Grazing Stalks --Too Long or Too Close: Let’s go back to those cornstalks. The stalk, which is typically the last plant part consumed by livestock, contains the most moisture and is one-half of the dry matter weight of the total residue material, however we may have to be very careful about leaving cattle in a field of stalks after they get through with the corn, leaves and shucks. As you can see, cornstalk residue is a tremendous resource for fall and winter grazing; however, this year care needs to be taken in grazing drought stressed cornstalks due to the potential of high nitrates in the feed. Cattle prefer grazing the leaves and husk which tend to be lower in nitrates. Because drought stressed corn is smaller and stunted, it is more likely that cattle will eat lower into the stalk where nitrate levels may be high. Nitrates are usually concentrated in the bottom third of the stalk in the corn plant. High nitrates may not only be an issue in dryland acres but also on irrigated corn edges and in the corners where water hasn’t reached and plants are stunted. Cattle tend to prefer these drought stressed plants when grazing. They will graze them right into the ground if you let them. There is the potential that cattle could seek out those plants when first turned onto a pivot-irrigated field, so you may want to keep an eye on them.
We are likely to leave cows grazing cornstalks longer than they normally would to try to stretch feed resources. Forcing cows to eat more of the stalks increases the risk that they will be consuming parts of the corn plant that could be toxically high in nitrates. Following are suggestions for grazing potentially high nitrate cornstalks: Don't turn cows into drought stressed cornstalks hungry, make sure the cows are full as this will help them adjust; fence out pivot corners and edges where plants are severely stressed; resist the temptation to leave cattle on corn stalks after they have eaten most of the leaves and husks; avoid forcing the cattle to consume more of the potentially high nitrate stalks; and consider giving cattle a dose of nitrate utilizing microbes 7-10 days prior to turnout which will help cattle adjust to utilizing potentially high nitrate feed. (Note: Bova-Pro is an example of a product. You may want to remember that the use of this product doesn't eliminate the risk of nitrate poisoning when grazing high nitrate feed; it only helps cattle adjust to it.) ---- Happy stalk grazing!

The preceding information comes from the research and personal observations of the writer which may or may not reflect the views of UNL or UNL Extension. For more further information on these or other topics contact D. A. Lienemann, UNL Extension Educator for Webster County in Red Cloud, (402) 746-3417 or email to: dlienemann2@unl.edu or go to the website at: http://www.webster.unl.edu/home