A low-cost feed resource available to a cow-calf producer is grazing crop residues. University of Missouri livestock specialists have received questions about cash-renting stock fields, sustainable grazing periods and the nutritional profile of crop residues.

When determining the appropriate stocking rate and grazing time, it is important to consider the amount of residue that will be trampled and wasted in the grazing process. Research indicates cattle grazing a whole field will use only 20% of the residue.

Quality of feed
The nutritional quality of grazed corn residue is quite high early in the grazing period: approximately 70% total digestible nutrients (TDN) and 8% crude protein (CP), which will gradually decrease over time to approximately 40% TDN and 5% CP. This reduction is a result of cattle selecting the highest-quality feed first, then weathering and leaching of nutrients from the residue over time. Cattle will first consume any grain that remains, then shift their preference to leaves and husks, finally moving to cobs and stalks.

However, if harvesting conditions become less than ideal, producers should give extra attention to the shape of the field and if equipment has buried much of the nutritional residue. Moreover, fields harvested late have delayed grazing days, which will be more susceptible to weathering and leaching of nutrients.

How many head
As a rule of thumb, grazing densities under ideal conditions should be figured one cow per acre per month of residue.

To determine when supplementation is necessary, producers should observe the manure from the cows. As corn in the manure begins to disappear, it is time to begin protein supplementation.

Many of the by-product feeds readily available are a great choice given their high-protein, low starch content, which aids in the digestion of much of the more indigestible material being consumed as the grazing period matures.

How much to spend
When renting stock fields, several factors need consideration to arrive at a "fair" rental value. First and foremost is the availability of water and fencing. Costs can rise significantly when fields are absent of both of these inputs. Some phosphorus and potassium will be removed from the field when stalks are grazed, but part of it is returned in the form of manure.

Finally, cornstalk residue is correlated to corn yield, which can account for the variance in price, so asking the owner what the field yielded is a definite.

Considering all the above factors, cash rental rates for stock fields have been documented between $5 and $15 per acre; however, typically the price falls between $5 and $9 per acre.

Source: University of Missouri Extension Ag Connection