When cattle get older, they tend to develop a weak vaginal lining which may cause an occasional prolapse. If she was predisposed to prolapsing, the ligaments in the uterus can become stretched, which will also contribute to prolapse. Given the fact that she is overweight, she likely has lost some of that muscle tone that helps to hold the reproductive tract in place. You need to monitor her carbohydrate/energy intake (i.e., no grain, sweet treat, or breeder cubes) and limit hay and grass grazing, if necessary.
