How long is the average pig?

"four months, four days."

Ok you are off just a little. First of all, you are thinking of the gestation period which is actually 3 months 3 weeks 3 days. the Estrous Cycle is 21 days. length of estrus is anywhere from 12 hours to up to 60 hours. The gestation period is the length in which the animal is pregnant. The estrous cycle is the time between 2 estruses. And an Estrus is the time in which they are fertile or in heat.