Feed is one of the greatest expenses for a cow-calf operation. For cattle producers with access to corn field residue, a golden opportunity is lying in nearby fields.
“Traditionally, winter feed costs have been a large chunk of feeding the cow herd, and management, which extended the grass grazing season, lowered feeding costs. However, pasture rental rates have increased substantially due in part to a decrease in pasture availability,” explains Mary Drewnoski, beef systems specialist for the University of Nebraska-Lincoln (UNL).
Grazing corn residue, or stover, is by no means a new method of wintering cows, but in an online survey by UNL in 2015, 39% of Nebraska farmers did not graze their corn residue, 39% grazed their own livestock on corn residue, 16% rented to other livestock producers and 6% grazed and rented fields. While this survey was only completed by 108 farmers, there were 9.15 million acres of corn harvested for grain during the 2015 Nebraska harvest, according to USDA. This means there is a lot of potential for winter feeding in an industry that is constantly feeling the pressure to be more efficient.
“Grazing corn residue is a very economically viable system,” Drewnoski says. “Honestly, right now, it is the lowest cost way to keep a cow no matter what time of the year it is, thus grazing corn residue can reduce cow carrying costs substantially.”
An exceptional amount of nutrition is left behind in corn fields each fall, she adds. Downed ears and kernels that drop through the combine are cows’ first go-to nutrient source, with the highest amount of crude protein and energy. Highly palatable husks and leaves are next in line, serving up the majority of the feed in the field, with corn cobs and stalks serving little value to cattle.
Stocking rate is directly tied to what the field’s corn yield was at harvest.
“As corn grain yield increases, the amount of stover increases,” Drewnoski says. “‑ e easy rule of thumb is that for every 100 bu. of corn, you can graze one cow for 30 days, based on a 1,200-lb. cow.”
Recommended stocking rates are based off cattle consuming all the grain and 50% of husks and leaves in the field, because cobs and stalks won’t keep cows on an adequate plain of nutrition. At the recommended stocking rate, only 15% of the field’s stover will be removed.
“If you stock at that appropriate rate, one cow per 100 bu. for 30 days, a mature cow should not need to be supplemented with any protein,” she says, referring to spring bred cows. “Cows can maintain their body weight, and we have seen no bene t in reproduction or to the calf with supplementation.”
However, if mature cows are coming off summer pasture a little thin, a body condition score (BCS) of 4, for example, then supplementation is needed. If available to the producer, Drewnoski recommends feeding dry distillers grains to fill the nutrition gap.
“A third of a pound per day of distillers will help her gain body condition on stalks to go into calving at the proper condition since we want to calve at a mini-mum of a 5 BCS,” she explains.
This changes when first and second calf heifers are wintered on corn residues. First calf heifers in mid-gestation are going to need about ½ lb. protein, Drewnoski says, and about 1 lb. of protein during late gestation.
“Half a pound of protein is what she will be deficient, which is almost 2 lb. of dried distillers a day early in the winter during midgestation,” she says. “Later in the winter, bump that up since she is going to be deficient to protein and energy, and give her 3 lb. of dried distillers.”
Regardless of cattle needing protein supplementation or not, Drewnoski recommends producers give cattle free choice salt and trace minerals with vitamin A due to the lack of green forage.
There are two ways producers can go about grazing corn residues. First is a long-term approach with a lower stocking density per acre to allow cattle more time per field. This method is best suited for producers with less access to fields, because cows might remain in one field long-term.
“This results in cattle having a very high plane of nutrition early as they are eating a high proportion of their diet as corn early in the winter, then a high proportion of husk and finally mainly leaves late in the winter,” Drewnoski explains. “The problem with this system is with spring calving, cow requirements are going up late in the winter because the fetus is starting to grow more rapidly.”
The second method is more of a ‑ ash grazing style, where higher stocking density is used on fields for a much shorter amount of time.
“With this type of grazing, the plane of nutrition cycles over a shorter period of time. Therefore the plane of nutrition in early winter is similar to late winter,” Drewnoski says. “Some producers take this idea one step further and only using stocking rates to use all of the corn and some husk resulting in cattle being maintained on an even greater plane of nutrition, throughout the winter.”
John Maddux, manager of Maddux Cattle Company in southwest Nebraska, has centered his entire operation around utilizing corn residues for up to five months out of the year to winter his 2,500 cow-calf operation on a year-round grazing scheme. While Maddux’s Red Angus foundation composite herd with Devon, Red Poll, South Devon and Tarentaise influences are bred to this grazing system, and the location of the ranch makes the operation unique, a lot can be learned from their 40-plus years of grazing cattle on corn residues.
The operation grazes large groups of up to 900 head for short periods on around 35 cow days per acre, adjusting accordingly if there are extremes of it being a high or low yielding field. Cows grazed on the heavier stocked fields, where there is more corn on the ground, are in just long enough to clean up fallen corn and husks, and are moved to the next field once the corn kernel count in their manure is low.
Because this method gives cows frequent access to the highest nutritional levels of corn, Maddux doesn’t supplement dry cows. However, in recent years, Maddux has started delaying weaning on pairs to 11 months and wintering cows with their mature calves at side on corn residues. While stocking rates are not adjusted to make up for the calf, pairs are supplemented 3 lb. per day of dry matter in the form of wet distillers feed.
“We have found this a very cheap and efficient way to winter a calf,” he says. “I think it helps our calves gain better on grass because they know how to hustle for feed. Since grazing corn stalks is a learned behavior, it makes replacements much better suited to graze stalks on their own the following year.”
The ranch also backgrounds yearlings on corn residues, doubling the stocking rate they use for cows. Calves are supplemented 5 lb. in dry matter in wet distillers grains for a calculated 1.5-lb. gain through the winter.”
“If we are running yearlings, we can get 70 calf days per acre,” he says. “But they need to be at least a 5-weight. Anything lighter is not physically mature enough to take advantage of the rougher cornstalks.”
One of the biggest misconceptions when it comes to grazing corn residues is it will cause soil compaction and impact yields. This isn’t completely wrong, Drewnoski says, how-ever there are positive impacts as well.
In a 16-year study by UNL researchers, fields of corn in an annual rotation with soybeans were grazed after corn was harvested. Sections of the field were stocked at one cow per acre for 30 days per 100 bu. corn yield stocking rate. Results showed the next season’s soybean yield increased on fall-grazed areas, from 62 bu. per acre to 65 bu. per acre, and subsequent corn yields were boosted 5 bu. per acre on grazed areas.
Why? It goes back to cattle speeding up the decaying process of crop residue and manure improving the soil microbial community, says Drewnoski, who has been working with a soil scientist to piece together the puzzle. is activity fosters a healthier environment for key bacteria to work more efficiently and pro-vide nutrients to plants.
But while yield increases, fields can become rougher as well, she adds, leading to uneven emergence. How-ever, when it comes to letting a field sit empty from fall to spring, or making money off grazing rent, farmers’ mindsets needs to be, “You don’t get paid for what it looks like in June,” Drewnoski says.
Note: This story appeared in the October 2016 issue of Drovers.