By Scout Nelson
As fall progresses, many producers may look toward grazing opportunities that involve alfalfa or sorghum forages. However, safety remains a priority due to the potential for bloating in alfalfa and prussic acid poisoning in sorghum species when frost occurs. Understanding these risks and using proper management can help reduce problems while making the most fall in grazing conditions.
In some situations, alfalfa may not have been large enough to harvest earlier in the season, or it may be conveniently located near cornstalk grazing. Grazing alfalfa in late fall can also help reduce alfalfa weevil issues by removing stems and plant parts where eggs may overwinter.
Even after several nights with temperatures in the 20s, alfalfa often stays green with leaves still attached to stems.
The common question asked is, "Can I be sure my cows won’t bloat if they graze my alfalfa?" It is not possible to guarantee that alfalfa will not cause a bloat. Bloat occurs when gas produced during digestion becomes trapped in the rumen. However, the risk is much lower about a week after a hard freeze that causes noticeable wilting.
To further manage this risk, livestock should be full before entering alfalfa fields, grazing should wait until frost or dew has dried, and additional dry feed or bloat-preventing supplements can be provided. Close observation during the first days of grazing remains essential. Alfalfa can be grazed safely with careful and realistic management.
Sorghum family forages, including sorghum-sudangrass and forage sorghum, carry a different risk after frost. When freezing damages plant cells, chemicals inside the plant mix and form prussic acid, a cyanide compound that can be deadly.
The highest risk occurs right after freezing and during new regrowth. Livestock should be removed immediately following frost, and grazing should resume only after five days, or when regrowth reaches 15–18 inches. High nitrogen soils can increase risk further.
By watching weather patterns, timing grazing carefully, and allowing toxic compounds time to dissipate, producers can safely use fall forages while protecting livestock health.
Photo Credit:gettyimages-eugenesergeev
Categories: Nebraska, Crops, Sorghum, Hay & Forage, Alfalfa, Weather