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Sorghum residue similar in performance to corn stover

UNL research shows that cattle can access sorghum residue easier in heavy snows.

March 3, 2015

3 Min Read

Grain sorghum is a crop that can withstand substantial water shortage and produce acceptable yields as long as the growing season is favorable for its maturity. In recent years, according to Karla Jenkins, a Nebraska Extension cow/calf and range management specialist in Scottsbluff, grain sorghum has begun to gain popularity again in Nebraska for several reasons. The drought of 2011-2013 made the hardy crop more favorable in areas of Nebraska where either irrigation is limited or where dryland cropping occurs, she says.

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According to a June 2014 National Agriculture Statistics Service report, 140,000 acres were planted for sorghum grain harvest in 2013 and that grew to 160,000 in 2014 in Nebraska. Grain sorghum also qualifies as an advanced biofuel increasing its appeal to ethanol plants.

However, the byproduct of the sorghum crop most beneficial to cattle producers may be the crop residue itself. Research evaluating corn residue and sorghum residue for growing calves was reported in the 1990 Nebraska Beef Cattle Report. Researchers back then found cattle grazing corn residue fields gained more than those grazing sorghum residue fields, most likely due to the amount of residual grain left in the field. Grain harvest efficiency has improved and these differences have likely decreased. However, the researchers also reported that in a winter with 15 inches of snow, cattle grazing sorghum residue had an advantage due to more available leaf residue. This is most likely due to the harvest method of sorghum.

The sorghum head is clipped off and the majority of the leaves and stems are left standing. This creates a digestible forage resource (about 56% total digestible nutrients) that cattle do not have to dig through the snow to find.

While the leaf material is similar in TDN between corn and sorghum residues, the sorghum stalk is greater in digestibility than the cornstalk. Find more information at http://www.ianrpubs.unl.edu/sendIt/ec278.pdf. The risk of digestive upset from the overconsumption of grain is less for sorghum than for corn due to the small size and coating of the sorghum berry.

Similar to corn, about 16 pounds of dry matter is produced for every bushel (56 pounds) of grain produced. Only about 50% of that is consumed by the animal, so producers can figure 8 pounds of dry matter residue is available for every 56 pounds of grain produced.

A study in the 2010 Nebraska Beef Report showed that cattle grazing a brown midrib variety of grain sorghum had greater daily gain and ending body weight than cattle grazing a traditional variety of grain sorghum. The increased performance was most likely due to the increased digestibility of the fiber which was also reported in that study. The calf gains were similar to those of calves grazing corn residues.

As pasture becomes more limited and more expensive, crop residues will become increasingly important to the profitability of cattle operations. Grain sorghum residue provides similar quality to corn residue and can be more accessible in winters with deep snow cover.

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