Cows cannot eat day lilies. What you can eat is called day lily, which is day lily. Hemerocallis grandiflora contains a lot of colchicine, and cows will have poisoning reactions such as nausea and vomiting if they eat it by mistake. Hemerocallis grandiflora is mainly used as an ornamental plant variety, which is usually only suitable for viewing and cannot be eaten by mistake. If you eat it by mistake, you need to deal with it immediately to avoid some adverse reactions and even death to cattle.
Eating HEMEROCALLIS grandiflora by mistake will endanger the respiratory system and digestive system of cattle, and even endanger life. As for whether cattle eat day lilies, it's really uncertain. It depends on how much it eats, but try not to give it to cows.