Source: Ontario Ministry of Agriculture, Food and Rural Affairs
Corn stover can provide a low cost feed source for mid-gestation beef cows. The energy in a cornfield is half in the grain and half in the stover or plant material. Once the crop is harvested, half the feed energy remains in the field. The cows can enjoy an additional benefit by gleaning the kernels and small cobs that passed through the combine.
Most fields will provide between one and two months of grazing per cow per acre (50 cows on 50 acres for one to two months). However, cows should be monitored closely and body condition scores recorded, so that necessary supplementation can take place when required.
The feed value of the stalks will drop from harvest date, so the earlier in the season you can graze, the better. Initially the Total Digestible Nutrients (TDN) value could be as high as 70 percent, but as the winter progresses this value will drop down into the 40 percent range. This decline is partly due to the weathering of the leaves and stalks and partly due to the cows eating high-value grain and leaves early in the grazing, leaving lower-value stalk material for later grazing.
Check the field for available grain – both kernels on the ground and small cobs missed by the combine. If there is a significant quantity, you may need to limit access so that the cows don’t overload on grain. Use temporary electric fence to strip-graze the field or restrict the grazing time to a few hours during the day. The cows will tend to eat the grain first, then the husks and leaves and lastly the stalks. Control the size of the grazing area to help keep the energy level of the cows’ diet more uniform during the grazing period. Once the leaves and husks have been consumed, you may have to supplement with good quality hay. Monitor the manure for any visible signs of grain. If no grain is present in the manure, it’s time to start supplementing. A 1300 pound cow will require about six pounds of good quality hay to meet her protein needs at this time.
Ensure that salt and mineral is freely available at all times. Provide an accessible source of water, since cows will consume about 10 gallons of water per head per day, under cool conditions. Later in the season, lean fluffy snow can serve as an optional source of water.
Soil condition is also an important consideration for grazing corn stover. If the ground is wet, there will be some pugging and roughening of the soil surface. In a no-till cropping system, you might consider waiting until the ground is frozen or selecting the driest fields with a low clay content to graze. Any fall damage to soil structure will be at least partially rectified by the freeze-thaw action over the winter. Damage in the spring will have a more significant impact on the season’s crop. The feed value of the stalks will be higher in the fall than in the late winter or spring. It will be to your benefit to graze the stalks during the fall and early winter and remove the cows from the field before spring thaw conditions start. By managing the stover field as a pasture field (controlling the area being grazed and staying off it when soil conditions are wet) a producer can have the best of both the feed and crop worlds.