Not a pig but I had a friend who had a stunning Shetland mare. She had one foal as a 4year old then could not get in foal again. Her job became running with the stallion in the winter and she did this for years. then one morning when checking the ponies she had beside her a stunning little black filly, 10 years after having her first foal. That filly went on to win loads of championships and produce some beautiful foals of her own. nature is a funny thing.