To add to what Mike said, I remember coming back to Lime Street in the early hours about winter 1973 on a Class 40 with a long rake of ecs behind us, pitch dark and, in those days, only the feeble marker lights. We drew up to the stop blocks, and all Hell let loose. The front of the loco was covered in blood, and L&M main line was stopped while a search was made for the body. Someone, less squeamish that the rest, had a closer look at the front of the 40 and noticed pieces of hide tucked in various places, and obviously not human.
The remains of the prize bull were eventually found and removed from the tracks, although the farmer wasn't amused. We'd been climbing at the time of impact with the engine wound right up, and we neither heard nor felt anything.
Class 40s were rather on the heavy side, though, and with the buffing gear on the bogie. I was rather glad we hadn't had a dmu..