What to Watch for When Transitioning Cows from Pasture to Crop Residues
12 February 2026
1 minute read
By: Transitioning cow herds from pasture to crop residues for fall grazing efficiently utilizes available feed resources, but several important considerations extend beyond fencing and water supply. Summer growing conditions can elevate nitrate concentrations in crop residues, posing risks of acute toxicity and abortion in pregnant cows. Fortunately, nitrate testing is inexpensive and readily available through numerous laboratories. Water sources may also contribute to nitrate exposure, so dedicated water-hauling trailers are recommended rather than repurposed fertilizer tanks, as even small amounts of concentrated fertilizer residue can be difficult to dilute to safe concentrations. Additionally, the wet conditions experienced in many regions this fall have promoted significant forage regrowth, increasing the risk of prussic acid (cyanide) poisoning. Cyanide precursors are normally separated from the enzymes that activate them, but combine when plant tissue is damaged by chewing or frost. Following a killing frost, cattle should be withheld from affected fields for approximately seven days or until the plants are dry and brown to mitigate the risk of poisoning.
