– Rory Lewandowski, OSU Extension Agriculture & Natural Resources Educator, Wayne county
Over the past several weeks, a considerable amount of corn has been harvested for grain. The corn stalk residue or fodder that remains offers another grazing opportunity for beef cattle or sheep. According to a Penn State Extension publication entitled “Grazing Corn Stalks with Beef Cattle”, for every bushel of corn there are approximately 18 lbs. of stem/stalk, 16 lbs. of husk and leaves and 5.8 to 6.0 lbs. of cob left as residue.
According to a University of Nebraska beef production site, for a quick estimate of corn stalk grazing days for a 1200-pound non-lactating cow, divide the corn grain bushel yield by 3.5. Corn stalk residue does provide energy and crude protein but is low in mineral and vitamin A content, therefore a well-balanced mineral and vitamin mix should be provided free choice along with salt.
Cattle and sheep grazing corn stalk residue select and eat the grain first, followed by the husk and leaf and finally the cob and stalk. Typically, there is less than one bushel of corn ears dropped per acre unless the field has experienced high winds. One potential issue with selectively consuming the grain first is digestive upset/ acidosis, or in severe cases, bloat and even death. Before grazing, scout the field to determine if there are piles of grain that could cause grain consumption overload. In these situations, and/or if there are more than 8 to 10 bushels/acre of corn on the ground, a good grazing strategy is necessary to limit corn intake. The key is to increase the stocking density. Generally, this is done by limiting the grazing area. Strip grazing works well with corn stalk residue. As stocking density increases, selectivity decreases. Livestock are forced to eat more of the forage portion of the corn stalk residue, and thus dilute the impact of the corn grain.
Quality of the corn stalk residue declines over time and is highest in the first 60 days after harvest. The greatest loss of nutrients occurs in the husk and leaf portion of the residue and the decline is hastened by wet conditions. Shortly after harvest, it is not uncommon for livestock to graze a diet with a nutrient content of 65-68% TDN and 6-7 percent crude protein. Corn stalk residue quality declines over time, and without managed or strip grazing, diet quality could fall to a 40-45% TDN and 5% crude protein level. The rate of decline is dependent upon stocking rate, time allotted to graze a given area and environmental conditions. The greatest nutritional benefit from grazing corn stalk residue is generally achieved by planning for a 45 to no more than 60-day grazing period following harvest.