I got a yearling female in 1981 that had her first litter of 21 in 1983. She had babies every year up until she started having a inverted cloaca problem . Her last two litters were 93 and 94. She was still producing good litters but I felt like she was getting to old ?? I still have a good breeder male that was born in 1993 . I don't think ether of these cases are real extreme.