Producer Question from 2010
Q: We cut johnson grass last night to bale into hay for our cows. We had a hard freeze last night. Can we still use this hay? When can we cut more for hay to feed to beef cows? (October 29, 2010)
A: Johnson grass can produce prussic acid after the freezing weather. The formation of this is triggered when the plant cells rupture due to freezing. However, the prussic acid does dissipate from the plant in about 5 days. The hay you cut yesterday and that froze over night could still have had prussic acid form, but it will disappear as it dries down and even after it is baled. The remainder of the hay could be cut at any time. Both will be safe as far as prussic acid when the hay is fed this winter, Johnsongrass can also accumulate nitrates if it grew under drought conditions this past season. After all the hay is baled, it may be worthwhile to have a sample of the hay tested for nitrates to be safe.
Dr. Jerry Volesky, Associate Professor of Agronomy
West Central Research & Extension Center - North Platte, North Platte, NE