Is sorghum the best-kept secret for feeding cattle right now?

This year, sorghums may be a great option following winter wheat/cereals, in late-planting areas for silage or sorghum-sudans as an emergency forage in a failed alfalfa stand.

Jeff Jackson

Sorghum is one of the most efficient ways to grow the most dry matter in an annual crop I can think of. The USDA reports more than 6 million acres of sorghum were planted in the U.S. last year. Seventy-five percent of the sorghum crop was grown in Kansas and Texas, where dryland conditions may make it a more suitable alternative to corn.

There are a number of sorghum products available for forage uses and, depending on your end goal and management practices, your forage specialist can help you choose the ones that fit your operation.

Corn or sorghum? Environment matters

Under ideal conditions, corn will usually outyield sorghum crops. My recommendation: If you’re able to grow a really good silage corn crop, you should. But if you have challenging moisture-stressed ground or a hot climate, you may find corn doesn’t consistently perform well. That’s the sweet spot for sorghums.

Sorghums are very heat- and drought-tolerant. They thrive in less-than-ideal soils, such as steep hillsides or shallow soils where holding enough water to produce a good corn crop is difficult. Sorghum is approximately 30 to 40 percent more water-use efficient than a corn plant. In the hot, dry, moisture-limited environments typical of the West and South, producers can get equal to or better yields from sorghum.

Environment is probably the number one factor to consider when deciding between corn and sorghum. The cost of producing one or the other may also come into play. There could be significant input savings from growing sorghum instead of corn. For example, sorghum seed costs significantly less, basic weed control chemistries that work are inexpensive, and sorghum also requires less fertilization than corn, a further savings.

Nutritional benefits of sorghums

In a fairly short season, sorghums can quickly convert the heat units and sunlight energy into highly digestible dry matter animals can use. The ability to produce large amounts of forage in a short period of time makes them a great choice for double-cropping or delayed planting situations.

Nutritionally, the protein content and neutral detergent fiber (NDF) digestibility of the sorghum and corn silage are similar. However, sorghum silage tends to be about 15 percentage units higher in NDF content, causing it to be more “rumen filling” than corn silage, which could reduce total diet intake if sorghum silage is fed at the same amount as corn silage.

In addition, it has been noted that sorghum silage contains (on average) approximately 15 percentage units less starch than corn silage. This causes sorghum silage to have somewhat less metabolizable energy and rumen-degradable starch than corn silage. This could be an excellent feed source for growing heifers or brood cows. If the additional starch is needed, say for feedlot cattle, supplement the starch difference with starchy ingredients, such as corn, milo, hominy, etc.

Forage sorghum: Single-cut, high-moisture feed

Traditionally the term “forage sorghum” has been a catch-all phrase for the different sorghum products used for feed or forage. A true forage sorghum generally has little regrowth potential, making it ideal for single-cut, high-moisture harvest situations such as baleage or silage; a great alternative to corn silage in some environments. Its large, succulent, sweet stalks make good silage, but drydown can be challenging for making hay.

Historically, farmers have planted forage sorghum at high populations to keep stems thin and more digestible for their herds. New products, including both conventional and BMR sorghum varieties, are bred using the latest traits and technology to provide excellent fiber digestibility. Farmers who may be accustomed to planting forage sorghum at 15 pounds per acre will find that, with new products, planting population can be cut to 5 pounds per acre while obtaining the same high-quality feed without sacrifice of yield. Lowering the planting rate on the improved genetics also reduces the risk of lodging and enhances standability.

Sorghum-sudangrass hybrids: Multiple cut, flexible feed

Another option for farmers is a sorghum-sudangrass (SxS) hybrid. As the name implies, this is a breeding cross between forage sorghum and sudangrass, resulting in a plant with relatively smaller stems and more regrowth potential than forage sorghums. The rapid regrowth ability of SxS hybrids makes an ideal product for multiple-cut production systems. These hybrids are typically planted at higher populations than traditional forage sorghum, so there is more flexibility to make dry hay, baleage or graze.

In order to get the most from SxS hybrids, agronomic experts would say the first cutting should come 40 days after planting or when the crop reaches 36 to 40 inches tall, whichever comes first. Adjust cutting height to leave two nodes above the ground to enhance regrowth potentials; this may vary between hybrids, so take time to check.

Whether you plan to make hay or graze, these rules work. After the first cutting, you should be able to graze or cut again every 30 days until the first hard frost. If grazing, you can begin as soon as the plant reaches 18 inches tall; remove cattle when at least two nodes are left above the ground to increase regrowth potential.

As a SxS hybrid matures, the rate of growth slows down. If a farmer waits longer than 30 days between cuttings, quality may be compromised. By cutting a SxS hybrid more frequently, you benefit from a higher-quality crop and potential to increase yield over a one-cut SxS system. Adding a sorghum-sudangrass hybrid to your forage plan allows more versatility in harvest method or feeding purpose due to the flexibility of not being tied to one system. In a cow-calf situation where a higher-moisture feed may be needed, SxS products come in handy.

Sudangrass: Excellent regrowth, dry feed

Similar to SxS hybrids, sudangrass hybrids offer excellent regrowth potential and are another option for farmers looking to employ a multicut harvest strategy. These products generally have a finer stem than SxS hybrids, which results in better drying characteristics than other sorghum types. Sudangrass can be grazed, green chopped or cut for hay. Management is similar to SxS hybrids, and the 40-inch/40-day rule for the first cutting still applies to sudangrass hybrids.

All three types of sorghum have the ability to provide a consistent form of digestible fiber and energy. The energy content of sorghums per pound of feed is very high compared to many other forages. They are very efficient at converting sunlight and heat into readily digestible sugars ruminant animals can easily utilize.

Take advantage of new technology

Sorghum breeders continue to research ways to improve yield and quality for farmers. Most farmers are familiar with BMR sorghum, a natural genetic mutation to produce a plant with lower lignin concentrations. The result is a significant increase in whole-plant digestibility, higher dry matter intake (DMI) and increased feed efficiency. There are extra management considerations with BMR sorghums due to reduction of lignin.

It’s important to watch plant density and late-season harvest because lodging risk increases as stems become thinner and plants grow taller. This drawback has been addressed by breeding for the brachytic trait where plants have a shorter stature and a higher leaf-to-stem ratio due to reduced internode length, reducing the risk of lodging.

Breeders are using marker-assisted selection methods to identify traits for higher-quality and higher-tonnage potential. This method can provide farmers additional product options other than BMR or conventional. This third sorghum trait choice has an improved quality profile compared to conventional products but without some of the extra management requirements that can be present with BMRs.

Work with your local forage specialist to determine which products help meet your production and feeding goals. There are a lot of opportunities to improve profitability potential, and new technology is giving farmers more options for success.

PHOTO: Pictured here is a new forage sorghum hybrid selected by use of genetic markers for superior agronomics, yield and similar fiber digestibility. Photo courtesy of Winfield United.