Planting brown midrib sorghum sudangrass to replace corn silage

Unplanted corn acres due to cold wet planting conditions can be planted to brown midrib sorghum sudangrass to replace corn silage as a highly digestible fiber for dairy and beef producers.

Cold, wet weather conditions delayed corn planting this spring. Some dairy farmers began harvesting first cutting alfalfa before all acres intended for corn were even planted. Many of these acres may not have been planted. An alternative crop to replace corn silage is brown midrib sorghum sudangrass.

Brown midrib sorghum sudangrass is high yielding forage with highly digestible fiber. If planted in June, two cuttings can be obtained and can yield near that of corn on a dry matter basis. Brown midrib sorghum sudangrass can be planted as late as July 15 for one cutting. Soil temperature is critical for germination. Soils temperature needs to be at least 60 degrees Fahrenheit and 65 is preferable. Warm soil temps typically are not a problem, but this year has been particularly cool. If harvested at 36-48 inches tall, the energy content is similar to corn silage and crude protein concentration ranges from 15-20%.

As is the case with all sorghum species crops, prussic acid poisoning can be a problem. Prussic acid is found in its highest concentrations in the leaves and new shoots making grazing cattle most susceptible. Frost and severe drought frequently increase prussic acid content and should not be grazed under these conditions. However, prussic acid poisoning usually is not a problem in stored feeds. Concentrations of prussic acid decrease during the sun curing and fermentation process. Brown midrib sorghum sudangrass can be stored as chopped silage, round bale silage and sun cured hay.

Another potential problem can occur during the wilting process. Sorghum sudangrass can hold water after cutting and not dry to an acceptable moisture level for fermentation. While this crop can dry rapidly under ideal drying conditions the large mass of forage can inhibit drying, especially if the crop is allowed to grow to heights above 48 inches. In addition to drying problems if the crop is allowed to grow beyond the recommended height, forage quality rapidly decreases. To aid drying, crimp the stems and lie in a full swath but avoid over drying. Conversely, if drying conditions are ideal this crop can dry too rapidly creating fermentation problems associated with dry silage. Brown midrib sorghum sudangrass should be chopped between ¾-1 inch for bunker silos and slightly longer for upright silos and baggers to ensure effective fiber content.

The final deciding factor of whether to plant an alternative forage crop may be the yield and progress of other crops. Some have indicated first cutting alfalfa was harvested at high quality and yields were good. Conversely corn is going to be close as to whether it will ripen and produce harvestable grain. If the corn crop doesn’t ripen or is damaged by early fall frost, lots of that will be chopped for silage. Decisions of planting an alternative forage crop may be determined based on the speculation of traditional forage supply.

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