Sudan hay is a fast-growing, annual warm-season grass used as a valuable forage source for livestock, especially in arid and semi-arid regions. It is utilized during summer when traditional cool-season pastures slow down due to heat and drought. Its popularity stems from its ability to tolerate dry conditions and its capacity for rapid regrowth after being cut or grazed.
Characteristics and Classification
Sudan hay originates from the species Sorghum sudanense, a member of the Sorghum genus related to grain sorghum and Johnson grass. It is often cultivated as a hybrid, known as Sorghum-Sudan grass, which combines the fine stems and rapid regrowth of Sudan grass with the higher yield potential of forage sorghum. This warm-season annual grass typically reaches four to seven feet in height and has relatively slender stems, which aid in the drying process for hay production.
The plant grows aggressively under high temperatures, preferring well-drained soils and full sun exposure. Its fine-stemmed structure distinguishes it from thicker-stemmed forage sorghums, allowing it to dry more quickly when cut for hay. Due to its rapid maturity, it can be ready for its first harvest as early as 45 days after planting, offering multiple cuttings during a single growing season.
Nutritional Value and Forage Applications
Sudan hay is a highly palatable feed source for livestock, including cattle, sheep, and goats, used as hay, silage, green-chop, or pasture. Its nutritional profile, particularly the crude protein content, varies significantly based on the plant’s maturity at harvest. When harvested in a vegetative state, before the seed head emerges, crude protein levels can be comparable to mature alfalfa, sometimes exceeding 10%.
As the plant matures and begins to head out, the feed quality rapidly declines because fiber levels increase and protein content drops. This decrease in feeding value makes the forage more suitable for livestock with lower nutritional requirements, such as dry cows or replacement heifers. Its high yield potential and rapid recovery make it a valuable option for summer grazing programs and silage production.
Toxicity Risks in Feeding
A significant concern when utilizing Sudan hay is the potential for toxicity due to the accumulation of compounds, primarily prussic acid and nitrates. Prussic acid, also known as hydrogen cyanide, is formed from cyanogenic glucosides within the plant, converting to poison when the plant cells are damaged. Conditions like drought stress, frost damage, or very young growth (under 18 to 24 inches tall) cause these compounds to build up to dangerous levels.
Prussic acid poisoning is acutely rapid in ruminants like cattle, often causing death within minutes of consumption because the compound prevents the animal’s cells from utilizing oxygen. Conversely, nitrate accumulation occurs when the plant absorbs high levels of nitrogen but cannot convert it into protein due to limited water or cloudy weather. High nitrate concentrations are found in the lower stems and remain concentrated even after the forage is dried and baled as hay.
Monogastric animals, such as horses, are less susceptible to nitrate toxicity but should not graze on Sudan grass due to the risk of developing a neurological condition called cystitis syndrome from chronic cyanide ingestion. While prussic acid levels dissipate as the hay properly cures, nitrates do not volatilize and can still pose a threat in stored forage. Testing hay for nitrate concentration is a necessary precaution before feeding it to any livestock.