I had a 12 year old cow, she never had a heifer in her life
One year, I started off with 8 heifers and 2 bulls... was sure I was going to be heavy on the heifers by the end of it, but the next 10 were 8 bulls and 2 heifers...
My oldest grandma cow had 16 calves, 11 of those were heifers