Grazing is the easiest way to harvest crop aftermath. Grazing crop residues allows animals to select a higher-quality diet than would otherwise be obtained by harvesting and mechanically feeding. In grazing scenarios, ruminants will preferentially consume grain and leaves before consuming lower quality stalk material. This is an important consideration when developing diets based on crop residues.
Stocker cattle may have acceptable gains if allowed to selectively graze residues. Younger cattle should be removed from the field or supplemented with protein and energy feeds once high-quality residue components are consumed. Depending on the number of animals and the acreage, stocker cattle can graze on residues until cattle performance declines or feed quantity or quality becomes limiting. Cornfields with excess downed ears can create potential issues with founder/acidosis when grazing corn residue. Cows with experience grazing cornfields will seek out downed ears. However, stocker cattle do not initially seek out downed ears and can slowly adapt to excess downed ears. It may be necessary to step stocker cattle up to five pounds of corn before turning out. Using stocker cattle to consume excess downed corn can be a cost-effective way of adding gain while minimizing founder/acidosis issues with your cow herd. Mud and snow can reduce access to forage, limiting intake and selectivity, and ultimately reducing diet quality.
Water supply and fencing must be addressed prior to grazing crop residues. Portable waterers and electric fences can provide low-cost, temporary methods of fencing large areas of crop aftermath. We recommend cross-fencing and strip grazing for longer periods of grazing or for grazing large acreages. In some cases, wind protection also may be necessary for grazing into the winter months.
Mechanically harvesting crop residue (baling, stack wagon) often leaves the higher-quality components (cob, grain, etc.) in the field. Chopping residue adds more expense and is recommended only when crop residues will be included in a total mixed ration (TMR) or as a method to reduce feed waste.
When stacking or baling dry corn residue, wait until the moisture content has dropped below 20% to 25% or the temperature has fallen late in the fall to avoid mold in the stored material. Corn stover can be packaged in large, round or square bales. A flail harvester or rotary mower may be used to cut stalks prior to baling. Wait until stalks are dry after combining to minimize spoilage in mechanically harvested residue.
Low-quality feeds (straw, corn stover, beet tops, etc.) can be fed when cow nutrient requirements are low, such as during the second trimester of gestation following weaning. Alternatively, they can be blended with higher-quality forages for stages of production with greater nutrient demands. Supplemental macro and micro minerals and vitamin A usually are needed when rations include large proportions of crop aftermath.
A number of low-quality forages can be fed to dry cows and replacement heifers, including small-grain straw, corn stover, sunflower stover, slough grass and others.
Feedlot diets can use low levels of crop residue in growing rations (maximum of 20% to 30% of diet dry-matter, depending on desired performance levels) and finishing rations (maximum of 6% to 8% of the diet dry-matter).
For additional information regarding harvesting and use of residues, see NDSU Extension publication AS1548, “Utilizing Corn Residue in Beef Cattle Diets.