My experience with breeding mini jennies has been different with every animal. Some of my veteran jennies showed signs of bagging and relaxing at the croup. A few of my maidens did not show any bagging or even waxing. They carry for a full 12 months and you must wait 90 days after covering to run a blood test. I would ask the vet to run a blood sample on her to be safe. That way you can be assured her nutritional needs are being met. I would recommend keeping a close eye on her if bred, many of my friends with mini donkeys have have had to assist with foalings and it seems to me that statisticly we have had more problems with them than with the horses.