We live in central Ohio and have recently lost 3 purebred heifer angus calves. The first two were born unable to lift their heads, legs out straight, to weak to get up, and unable to suck. No signs of scours and calves appear fully developed.The 3rd calf was born healthy but developed the same illness 10 days later. The calves get sick suddenly and die quickly. We have tried penicillan, tetnus vaccine, sellinium injections, and tubing collostrum down because calf won't nurse. The sellinium and collostrum seemed to perk the 2nd calf up a little initially and lived 3 days. The vet has no idea what it could be. It doesn't appear to be black leg as there is no crackling sound when muscles pressed. It seems like maybe a genetic muscle disease, but its never been a problem before. The calves have been kept in a feedlot with sawdust base and lots of mud in some areas. Also last summer was extremely wet and rainy. The 3rd calf is being atopsied. Does anyone have any ideas what this could be?