Sorghum: An alternative option in dairy forage systems

Sorghum silage has been used as an alternative to corn silage for decades, particularly in regions with limited rainfall and high temperatures. Sorghum in dairy rations, however, has historically carried a reputation for poor digestibility compared with corn and was traditionally fed to heifers and dry cows rather than included in lactating dairy rations. Corn silage remains the gold standard for dairy forage due to its high energy content, high digestibility, and high biomass yield (Figure 1); however, as water scarcity intensifies in established dairy regions like the Southwest and the Great Plains, it may be beneficial to provide a review of sorghum. 

Recent developments in the seed industry, weed control, and nutrition research are challenging long‑held assumptions and are closing the gap between sorghum and corn. The intent of this article is to discuss forage sorghum broadly and to highlight recent research findings and agronomic developments that professionals working with dairies should be aware of to better advise their clients.

Sorghum is the fifth largest crop grown in the United States, with approximately 6.6 million acres harvested for all uses in 2025, behind corn, soybeans, wheat, and cotton (USDA, 2026). While it is commonly grown in the southern U.S. and regions with limited rainfall, sorghum can—and is—grown in all regions, including areas with adequate rainfall. 

Sorghum can be utilized in a wide range of harvest systems to fit farms of nearly any size and in almost any climatic region, though its best fit remains as a warm‑season cropping system. From a botanical perspective, sorghum represents a broad group of types suited to specific end uses with significant agronomic flexibility. Depending on the type, sorghum may be used primarily for grazing, hay, silage, green chop, grain, or biofuel production. The intended use dictates the type of sorghum selected. 

Agronomic fit and climate resilience

While sorghum is most common in arid regions with high evapotranspiration, it is also well suited for poorer soils, double‑cropping systems, emergency forage situations, and areas with consistent wildlife pressure. Sorghum production costs are typically lower than corn (American Farm Bureau Federation, 2026), and its drought and heat tolerance make it a valuable tool for climate risk diversification.

Growing degree units (GDUs) correspond to crop stage of growth and are useful in illustrating differences between sorghum and corn. Sorghum accumulates GDUs using a maximum temperature of 100°F in contrast to 86°F for corn, contributing to its superior performance under heat stress (Kelley, 2004). Ongoing breeding efforts aim to improve both heat and cold tolerance, enabling earlier planting and better avoidance of peak summer heat during flowering.

Water use and sustainability

Many dairies in the western U.S. rely on irrigation, often drawing from limited groundwater resources such as the Ogallala Aquifer in the Great Plains region where the dairy industry has increased. In other dairy‑intensive regions, surface water limitations and urban demand place additional pressure on water availability. While sorghum is not a panacea, it offers an option for reducing water demand and diversifying forage systems in these water‑limited regions.

Grain sorghum (milo) has been selected primarily for grain yield and is shorter in stature than forage types. It is the most widely grown sorghum type by acreage. The primary use of milo is for an energy source in livestock rations similar to corn grain. When properly processed (ground or dry‑rolled), milo provides approximately 90% of the energy value of corn grain. Processing is essential to break the hard seed coat and improve digestibility. Steam flaking can further increase its energy value. 

Forage sorghums are selected for biomass production and are typically used for silage or green chop. These plants are tall—often exceeding 10 ft—and generally do not regrow after harvest, making them well suited for single‑cut silage systems.

Sudangrass (Sorghum bicolor var. sudanese) is adapted for grazing or multiple hay cuttings and will regrow after harvest until frost. It grows rapidly, making it a good option for emergency forage or summer feed and is also widely used as a cover crop. However, it produces less biomass than forage sorghum or sorghum‑sudangrass hybrids.

Sorghum‑sudangrass hybrids (Sudex) combine traits from both parents. Like sudangrass, they can be grazed or harvested multiple times, but they are taller and higher yielding.

Sweet (syrup), sorghum and broomcorn are additional specialized sorghum types. Sweet sorghum has high soluble sugar content and may be used for biofuel production but is not well suited for dairy rations or ensiling.

Key forage sorghum traits for dairy systems

Forage sorghums may further be characterized by specific traits that influence management and feed value (Table 2). These types are photoperiod sensitivity (PS), non‑photoperiod sensitivity, male sterile (MS), and brown midrib (BMR). 

Brown midrib (BMR) hybrids have reduced lignin content, resulting in improved digestibility and high quality silage. Because lignin contributes to structural strength, early BMR varieties were prone to lodging, but modern breeding has greatly improved standability. When harvested at the soft‑dough stage (approximately 65–70% moisture), modern BMR hybrids typically show good lodging resistance.

Photoperiod-sensitive (PS) sorghums remain vegetative until day length shortens in late summer or early fall, resulting in tall plants with very high biomass. However, these plants often have higher lignin levels (unless combined with BMR genetics) and are generally better suited for heifers or dry cows than for high‑producing lactating cows.

Non‑PS forage sorghums mature based on accumulated growing degree units, allowing more predictable harvest timing and easier coordination with custom harvest operations. These hybrids are shorter, have lower lodging risk, and typically produce more consistent fiber quality. While yield is generally lower than PS types, improved forage quality and harvest flexibility can offset this difference. Non‑PS hybrids may also include the BMR trait.

Male‑sterile (MS) sorghums do not produce grain, which prevents energy from shifting into seed production. As a result, more energy remains in the stems and leaves, resulting in higher sugar concentrations, reduced lignification, and improved fiber digestibility. Male sterility may be present in either PS or non‑PS hybrids and is often combined with BMR genetics. Because there is no grain to dictate harvest timing, MS hybrids offer a wider harvest window and reduced lodging risk.

Photoperiod sensitivity and male sterility are often confused, though they control entirely different plant functions. Photoperiod‑sensitive sorghums flower based on day length, while MS sorghums are unable to produce viable pollen and therefore do not set seed. 

Additional traits of interest

Brachytic dwarf sorghums have shorter internodes and higher leaf‑to‑stem ratios, resulting in shorter plants with excellent standability and harvest efficiency. When combined with BMR genetics, these hybrids can produce high quality silage suitable for dairy rations. Brachytic dwarf genetics may be incorporated into various sorghum types depending on breeding goals. 

Nutritional considerations and recent research

One of the major barriers to wider adoption of sorghum in dairy rations has been its lower digestibility, particularly due to the hard sorghum kernel (berry), which tends to pass directly through the digestive tract. Properly processed sorghum silage can substantially improve starch digestibility and animal performance. Recent advances in forage harvest equipment have improved kernel processing in sorghum silage. This has the potential to significantly increase starch availability by breaking the berry and exposing the endosperm to rumen microbes, creating a higher quality silage more comparable to corn silage. 

Harvest chop length and harvest timing also interact with forage quality. Harvesting forage sorghum at the soft‑dough stage (approximately 65–70% whole‑plant moisture) improves berry fracture and reduces the proportion of whole grain in the silage.

A unique strategy to optimize forage quality is to focus primarily upon producing very high quality biomass by growing a MS-BMR sorghum type. This bypasses the issue of lower digestibility from the hard berry because there is no seed developed due to the MS trait. Since there is no seed harvested to provide energy value, the ration must be supplemented with grain. Since the silage is about 65% moisture, it makes economic sense to produce this in close proximity to the dairy to minimize transport of a bulky high-moisture fodder, and if needed, import grain at much lower moisture for supplementation. 

With this in mind, a recently conducted feeding study using MS-BMR forage sorghum in lactating dairy rations has shown that sorghum silage can replace up to 50% of corn silage without reducing milk production, provided that additional grain is included to balance energy (Duhatschek et al., 2026).

Anti‑nutritional concerns and misconceptions

When discussing the topic of sorghum, concerns about tannins, prussic acid (hydrogen cyanide), and nitrate toxicity persist. Tannins are largely a non‑issue in U.S. forage sorghum varieties as high‑tannin types are not used for forage production (Duff, 2021).

Prussic acid risk occurs in sorghum (but not in corn) and is associated with drought or frost stress. Ensiling greatly reduces prussic acid levels, while grazing and haying require greater caution. The chemical compound dhurrin is responsible for creating prussic acid in the plant. Recent dhurrin‑free (Penn State Extension, 2023) forage sorghum genetics have significantly reduced this risk and have become commercially available in limited varieties. Importantly, the BMR trait does not reduce prussic acid risk and is a common misconception.

Nitrate accumulation can occur in both corn and sorghum under stress conditions, particularly with excessive nitrogen fertilization and drought. Nitrates are concentrated in the lower portion of the stalk, so leaving adequate stubble height at harvest and testing questionable forage are critical management practices. Ensiling helps reduce nitrate levels but does not eliminate risk entirely. If there is doubt, it is advisable to test the forage.

Genetic complexity and breeding challenges

Sorghum readily outcrosses within itself, which presents tremendous challenges for crop improvement and modern weed management. Herbicide trait development in sorghum has been limited by the risk of gene flow to weedy relatives, most notably johnsongrass (Sorghum halepense) and shattercane (Sorghum bicolor var. drummondii), which are closely related off‑types and considered noxious weeds in many states.

Because sorghum easily crosses with these weedy relatives, herbicide traits that are now common in many major crops—most notably glyphosate tolerance—cannot be pursued due to the high risk of creating herbicide‑resistant weeds. This genetic and biological reality has historically constrained herbicide trait development in sorghum relative to corn much more so than technology constraints.

Herbicide tolerance and weed management advances

As a result of these challenges, post‑emergence weed control options—particularly for grasses—have historically been limited, and growers have relied heavily on pre‑emergence programs.

Recent advances have expanded these options. A newly developed trait derived from naturally resistant johnsongrass confers tolerance to ACCase‑inhibiting herbicides, allowing effective post‑emergence control of difficult grass weeds such as barnyardgrass, signalgrass, Texas panicum, and johnsongrass (Lovett, 2025). This provides an alternative mode of action and helps address herbicide resistance concerns. In addition, ALS herbicide tolerance has recently been introduced in sorghum, enabling post‑emergence grass control—an option that was previously unavailable in sorghum production systems.

Conclusion

Sorghum is an increasingly viable option for dairy forage systems, particularly as producers face greater climate variability, water limitations, and heat stress. Advances in sorghum hybrid development have improved forage quality, digestibility, prussic acid risk, and harvest flexibility. It has been demonstrated that well‑managed sorghum silage can partially replace corn silage in balanced lactating dairy rations without sacrificing performance. While there is more research that needs to be done, new technology that improves kernel (berry) processing and enhances starch utilization seem promising. Coupled with recent gains in post‑emergence weed control, sorghum is well positioned to be a climate‑resilient forage option.