WINTER IS COMING: Corn stalks a good grazing option for the pregnant cow
University of Nebraska
Late fall rains have been wonderful in a large part of range country giving a giving a good amount of subsoil moisture and allowing grasses to go into the winter in great shape.
Many producers are arranging for winter feed and as has been stated many times it is usually more economical to allow the cow to do the harvesting. In some cases this may be challenged this year as the price of hay in most of the high plains region is much less than in previous years. Because of the excellent and timely rains this year which gave excellent grass production many have the option of winter grazing at home which is usually the preferred and most economical winter feeding program. If a large part of the fall and winter feed can be supplied by dormant grass grazing then the lower cost hay and energy and protein supplements can be utilized later in the wither and early spring allowing the cows to be kept at home this year. When this is not an option grazing corn stalks offers a good winter forage for wintering the pregnant cow. I realize we write about stalk grazing each year so the following will be old hat for many but it seems each year we get calls concerning how many acres will be needed for a cow herd. In cases where not enough land it committed we then tend to overgraze and often lose cow condition. Ranchers that place cows with farmers for the winter should ask what guidelines they use for making grazing decisions if they have not worked with the farmer in the past. Also detailed plans for cow care and supplemental feed and who pays for what, especially in cases of extreme snow fall, should be decided before shipping cows.
As a general rule one acre of stalks will be adequate grazing for one mature cow for about 45 days. If for example it is planned to graze cows from December l to March 1, or a 90-day period one should budget for around 2 acres per cow. This number will vary with the amount of corn left in the field, corn yield, amount of other grazing such as ditch banks, plus ground conditions such as muddy conditions. More recent data from the University of NE offers some additional information to help delineate more precise carrying capacity based on corn grain yield per acre. Data where residues of the different parts of the plant were weighed found that the higher the yield the larger amount of residues present. From their data a formula was developed that estimated carrying capacity in cow days per acre by dividing corn yield (bu/acre) by a factor of 3.5. For example, corn that yielded 175 bu/acre would provide 50 grazing days for a cow. As with any rule of thumb the eye of the master needs to observe and move the cows when they no longer have quality grazing.
To aid in calculating the number of acres needed, based on yield of corn, and cow weight, Ag Economist at the University of Nebraska, Lincoln West Central Research and Extension Center has prepared and offer an excellent spreadsheet program at beef.unl.edu/web/beef/learning/cornstalkgrazingcal.shtml. It will estimate acres needed or if you enter number of acres and the corn yield it will estimate the number of cows a given acreage will graze for the time desired. It also will calculate costs per cow given the cost per acre of the stalks, transportation and daily care costs. As with any rule of thumb the eye of the master needs to observe and move the cows when they no longer have quality grazing. Transportation costs can be considerable if transported for a considerable distance. For example if 40 cows are transported 200 miles at $4 per loaded mile it will add $40/cow to the winter cost or if grazed for 90 days it adds $.44 to the daily costs.
Many have the opinion that cornstalks no longer have the value they did several years ago. Also the corn producers sometimes feel that grazing stalks will lower subsequent crop yields on grazed fields. This is stated so frequently that is seems that it must be fact but controlled research does not support these myths. It is true that farming and harvesting practices are improved today, to the point that very little corn is left in the field and yet every year I get calls on how to deal with too much corn in the fields. The general comment and some believe that GMO corn has decreased palatability and digestibility of the corn plant. Good controlled research has proven this is not true.
Researchers at the UNL West Central Research and Extension Center at North Platte, Nebraska has done considerable research on stalk grazing and subsequent crop yield They have investigated grazing intensity, number of cows per acre and at different times of the year as well as almost total stalk removal by baling. There data has indicated that stalk grazing only removes 11 percent to 25 percent of the residue but assuming 55 percent digestibility of the forage consumed then 45 percent is returned to the field surface leaving very little that is removed from the field when grazed. In general, where less than 50 percent of the leaves and husk are removed subsequent corn and soy bean yields are not adversely affected and in the case of soybeans yields were increased slightly. In their work it was found that if more than 50 percent of residue is removed such as from baling then there is more soil erosion, from both wind and water plus less residue is left for mulching. It was interesting to note that when the subsequent corn crop was no-till planted and no residue removed (no grazing) yields were decreased 20 – 25 bushels per acre. For more detailed information on all of the research and the details at UNL concerning corn stalk grazing one can read various research articles in the NE Beef Reports at: beef.unl.edu/web/beef/reports
In general corn residue provide a tremendous amount of forage for winter grazing. In spite of current beliefs by some, research has found that GMO has no adverse effect on the palatability or digestibility of the corn residue. Grazing cornstalks in controlled research has not shown any detriment effect on subsequent crop yields.
I hope things go well for you as you wean calves this fall.