There were a lot of corn acres harvested around the state this past week. Those acres represent an underutilized feed source that could help stretch feed supplies. This corn residue feed source is best used within the first 30 to 60 days after harvest. According to an October 2014 article on grazing corn residues by Rick Rasby, University of Nebraska beef specialist, for every bushel of corn (56 lb. per bushel) there is about 45 pounds of residue on a dry matter (DM) basis. Research shows that for every bushel of corn there is about 16 pounds of husk and leaves on a dry matter basis. Using those figures, a 170 bu/acre corn crop will leave 7,650 lbs. DM of total residue with the husks and leaves accounting for about 2720 lbs. of that total. In addition to the plant residues, typical harvest losses leave about 1 bu/acre of corn grain. Livestock will selectively graze the most palatable portions of the residue first, starting with the grain, leaves, and husks and then the cobs and stalks.
The livestock classes that match up the best for grazing corn stalks are non-lactating mature beef cows in mid-gestation and ewes in the middle trimester or earlier of gestation. The other note is that these animals should not be thin going into grazing corn stalks. Although selective grazing combined with low grazing density can allow for higher diet values, on average livestock will be consuming a diet of approximately 6% crude protein and 50 to 55% TDN.
University of Nebraska research suggests that designing a grazing strategy to remove about 50% of the leaf and husks, leaves plenty of residue on the field, while allowing good animal performance. Applying this guideline to the earlier 170 bu/acre corn field, if I have a 1400 lb. beef cow eating 2.5% of her body weight in dry matter per day, one acre will provide approximately 38 days of grazing.