We have lost five calves this year. three were out of heat wave clones, and two out of heat wave sons. All have been born without an umbilical cord attached as if it broke off inside the navel. Three came a week or two early and two were full term. I am wondering if any of you have ideas about the umbilical cord problem, is it genetic or is there something i am missing in our vaccination program? The calves were born alive but would not suck or get going.