So many conflicting numbers and reports. Such piss poor media anymore you don't know what to believe for sure. I've heard numbers anywhere from 200 2,000 10,000. In perspective even 10,000 is a drop in the hat compared to the number of cattle in most Kansas feed lots anymore. If these deaths are pretty scattered out in an area I can believe heat. If there's a big bunch and one group I would be testing feed real fast most of these places are feeding a lot of silage . Most any stem type grasses or crop can get high in nitrates in certain conditions. I personally know of one neighbor that lost 50 steers due to nitrate poisoning. Too much nitrogen in the soil along with drought and dryer conditions you would best be testing your crop before cutting for silage or hay. Granted some types are much worse than others for this.