Have only had a couple and one was truly retarded. Vet said that he may have been a harder birth, but he was on the ground when we found him although tongue was swollen some. Could not find his way to the teat without help for days, and we penned them for nearly 2 weeks to make sure he was getting to eat. He just wasn't right and then one day he was dead. Have had a few others and all have been bull calves. Haven't noticed them from certain breedings, though twice it was on the same cow and the second time was her last calf.