Grazing stalks can be a valuable tool for producers trying to stretch out fall pasture and/or reduce early hay feeding. One of the first advantages achieved with grazing corn stalks in fields is nutrient retention. Most nutrients consumed are readily returned to the field and usually in a more available form than before. If stalks are “strip” grazed (allocated out in days or weekly intervals) nutrient distribution is very good and fodder quantity and quality being grazed will be a little more stable from day to day. If there is a lot of corn (grain) on the ground, then strip grazing is really important to greatly lower the risk of foundering. I don’t see this as too much a problem this year unless you have a lot of down corn or where spillage from loading areas occurs.
The nutritional value of corn stalks can vary from year to year. If you were to watch the cows graze it, you would find that they would graze or select what they are consuming in this order – any grain, then leaf, husk, and cob (somewhat dependent on variety) and lastly the stalk or stem. “Stalks” will start out in the 8% crude protein range with approximately 70% total digestible nutrients (TDN) and over a period of about 60 days will drop to 5% crude protein and 40% TDN. Spring-calving cows will meet most of their energy needs during mid-gestation. Growing animals such as calves and fall calving lactating cows may be lacking a little in energy and protein and most likely will need to be supplemented if they are run on stalks.
About one acre of typical corn residue will be needed per animal unit per grazing month. Weekly allocations seem to work very well so you need to figure how many acres of stalks will be needed for one week of grazing for your herd. Take number of cows times the average weight times 0.03 (average dry matter (DM) intake) times 7 days.
50 cows X 1,100 pounds X .03 X 7 = 11,550 pounds DM needed
Now take corn yield times 0.4 (utilization) times 56.
180 bu. X 0.4 X 56 = 4,032 pounds per acre DM
Now divide needed pounds for one week (11,550) by pounds available per acre (4,032) and the answer is about three acres. This is a nice conservative estimate of acres needed.
With all of that said, this all is dependent on several other variables including drinking water availability, fencing, and soil and site conditions. For a field to be “usable,” it is going to have to have water available or a portable system utilized. It is also going to have to have an adequate fence to keep the cows where they are supposed to be; neighbors and passing cars seem to appreciate that. Temporary fencing (step-in posts and poly-wire on a reel) can then be utilized for those regular allocations.
Although not ideal for new forage growth or fall crops, drier conditions are ideal for grazing corn residue. Grazing stalks during wet soil conditions can increase the chances of compaction, especially on heavier soils. In Indiana. most compaction associated with grazing corn residue is in the upper layer and is normally fractured by spring by freezing and thawing.
Fields should ideally only be grazed under drier conditions as well as planted to a cover-crop such as wheat or cereal rye to help trap valuable nutrients and prevent erosion. If the field is considered highly erodible land (HEL), then you will want to ensure that adequate residue levels are being maintained according to your conservation cropping plan. Consult your local soil and water conservation office for questions regarding compliance.
Corn residue can be quite low in most minerals, especially calcium and phosphorus. A well-balanced vitamin and mineral mix should be provided, free choice, for the scavenging cows.
Remember, it’s not about maximizing a grazing event, but maximizing a grazing season!
Keep on grazing!