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Save Your Hay By Grazing Corn Fields
DR. TERESA L. STECKLER
SIMPSON, ILL.
This growing season has been strange to say the least. We had ridiculous amounts of rain in July and August. But since the beginning of September certain areas are as much as 7 inches less than average! With the lack of rain, many pastures look like July pastures – brown and dry with little growth to no new cool season forage growth.
In my travels I have seen quite a bit of residual corn growing in the fields. I spoke with one farmer who said that a corn field in Missouri was close to tassling for a second time this year! While that is a bit extreme, the residual corn growth in those fields can provide cattlemen with nutritious source of feed while conserving baled hay, allow stockpiling of perennial pastures for late fall/early winter grazing, and reducing production costs. Keep in mind that feed costs have been identified as the largest single cost of livestock production, making up 50 to 70 percent of the total cost of production.
Any corn hybrid can be grazed. There are several differences between hybrids for grazing or silage production versus those for grain production. Hybrids selected for silage or grazing have been bred for high forage yields, high digestibility, low fiber, and high fiber digestibility.
From the animal’s nutritional standpoint, grazing immature corn is similar to grazing other summer annual forages. Grazing corn in an early vegetative stage can provide a forage high in protein and digestible fiber.
A demonstration conducted at the University of Wisconsin found that plants at a V9 stage (stalk with only 9 leaves) contained 18 percent crude protein and ADF of 36.6 percent. As the plant matures and begins to develop an ear, the percentage of protein will decrease to 12-15 percent at tasseling and around 8% once the plant reaches maturity. The fiber content in the plant will also increase as the plant matures and begins to produce an ear because a significant amount of the plant is stalk at this point. However, the total digestible nutrients (TDN) increase once the plant sets grain and reaches the milk/dough stage because of the weight and high energy content of the grain.
Stocker cattle, beef heifers, and cows have excellent weight gains grazing corn. Dairy farmers have utilized corn, through grazing, to feed dairy cows and dairy heifers for breeding. Sheep producers have had success grazing sheep early on grazing corn when corn plants are 18 inches tall or less. Also goats and swine have all been used to graze corn successfully.
Even if the residual corn is not growing due to lack of rain, grazing corn stalks is still an excellent alternative feed source. Corn residue consists of grain, stalks, leaves, husks and cobs. An acre of corn produces about one pound of residue for each pound of grain harvested. For example a 150 bu/acre yield would leave about 8,400 lbs. of residue per acre. Of this about 50 percent would be utilized by cattle.
Corn residue is low in protein, most minerals, and vitamin A. Dry beef cows in mid-gestation that are in good flesh are the best class of animals to utilize crop residues as they have lower nutritional requirements. Nutritional requirements may be met early after turnout, being that cattle will selectively graze residues with high digestibility and corn left in the field first. During this time, only a complete mineral and vitamin supplementation product should be needed. With time, the combination of weathering and consumption of high quality residues leads to quality deterioration of the available residue. The rate of quality deterioration will depend on stocking rate and environmental conditions. Also, as the cow’s gestation period progresses, nutrient requirements increase while the quality of crop residues are decreasing. Protein and possibly energy supplementation will be needed along with a high quality mineral and vitamin supplement. This can be achieved using a variety of supplements, but some common ones include alfalfa hay, soybean meal, distiller’s grains, and commercial supplements.
When grazing residue, cattle will select and eat the grain first, followed by the husk and leaf and finally the cob and stalk. Usually there is less than a bushel of ear drop per acre, but this year due to the cobb being rubbery and smaller ears, there may be much more. Anytime more than about 8 bushels of grain per acre are left in the field after harvest, cattle grazing the stalks risk getting acidosis and founder. Both diseases are caused by excessive grain intake, which increases rumen acid production. This can cause severe foot and hoof problems, including lameness.
Prussic acid poisoning is associated with shattercane and johnsongrass which may be present as weeds in corn fields. If these weeds are present, then do not graze frosted fields. Wait several weeks following a killing freeze before grazing to prevent prussic acid poisoning.
In summary, grazing residual corn growth or crop residues offers potential for extending the grazing season and reducing feed costs. Dry mid-gestation cows graze crop residues well as they have lower nutritional requirements. Be sure to provide a vitamin and mineral supplement when grazing crop residues. As plant quality decreases, protein and energy supplementation will be needed. ∆
DR. TERESA L. STECKLER: Extension Specialist, Animal Systems/Beef, Dixon Springs Agricultural Center, University of Illinois
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