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Reduce Feed Cost By Grazing Corn Stalks

Producers looking for ways to reduce feed costs may consider grazing corn stalks, said Julie Walker, SDSU Extension Beef Specialist and Associate Professor.

She explained that feed, which comprises more than 50 percent of a livestock producer's annual production costs, is the largest expense of a cow/calf operation.

"Harvested feeds are usually blamed for the biggest portion; however, with shrinking pasture acres and rising pasture rental rates, summer grazing costs can also be significant," Walker said.

One lower-cost option Walker encourages livestock producers to consider is grazing corn stalks. "Grazing corn stalk residue can reduce both the amount of harvested feeds required to get cows through winter and the annual cost per cow," Walker said. "The pounds of residue per acre, on a dry matter (DM) basis, at harvest are roughly equal to the pounds of grain produced or about 50 pounds per bushel of grain."

The estimated amount of residue for various corn yields is shown in Table 1. When determining stocking rates on corn silage, Walker said livestock producers need to remember that for erosion control and organic matter management, some residue should remain on the field.

Livestock producers should aim to leave some residue behind. When grazing corn stalks, Walker said cattle prefer to eat the dropped ears (grain), husks and leaves first as they are more palatable and digestible than cobs and stalks.

"Thirty years ago 3 to 4 percent of the corn ears used to remain in the field. With new hybrid varieties and improved harvesting efficiencies, only 1 to 2 percent of corn ears remain in the field today," she said.

According to research completed at University of Nebraska-Lincoln digestibility of the husks and grain provides cattle with enough nutrients to maintain body weight and gestation for beef cows without supplementation. However, Walker reminds livestock producers that nutritional quality declines through the grazing period as animals harvest the higher quality portions first and as weathering losses occur.

Nutrient composition of the diet selected at the start of the grazing period is about 6 to 7 percent crude protein and 65 to 70 percent Total Digestible Nutrients (TDN) compared to lower levels (5 percent crude protein and 40 percent TDN) at the end of the grazing period. "It can be difficult to estimate when protein supplementation is needed to ensure optimum utilization," said Walker.

She suggested that producers start supplementing protein when the corn in the manure begins to disappear. Spring calving cows should receive 0.5 to 1.0 pounds of supplemental protein from an all-natural source. Protein sources can include alfalfa, distillers' grains, oilseed meals and commercial protein supplements.  

Strip grazing Strip grazing provides animals with a small area to graze; however, it makes the quality of the diet more uniform over the grazing period, Walker explained. "Animals are forced to consume both the high- and low- quality forage components of the residue," she said.  

Consider compaction issues Some farmers are concerned about compaction issues if cattle graze their corn residue.

Walker said normal grazing practices, which place cattle on residue following harvest sometime in November and moves them off before March, reduces the potential compaction issues.

In fact, according to research conducted by the University of Nebraska, corn fields grazed by cattle experienced a slight numerical increase in subsequent soybean yields compared to un-grazed fields. And, researchers at Iowa State University suggest compaction is not an issue, if cattle are turned out after the soil is frozen.

However, when animals were allowed to graze prior to freezing, there was a small reduction in subsequent yield in a no-till system, but no differences were seen with conventional tillage.

"Proper management of livestock on fields can greatly reduce any concern about soil compaction," Walker said. To learn more about grazing corn stalks, reference the iGrow article, "Calves Grazing Corn stalks".

Table 1. Estimated corn stalks residue yield.

Corn yield (bu/ac)Residue yield (T/ac)
> 1204.0 – 5.0
90 – 1203.5 – 4.5
60 - 902.5 – 3.5
30 – 602.0 – 3.0
< 301.0 – 2.5

Source : SDSU

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