Swine Gestation Calculator

Industry practice is to move sows approximately 7-10 days before the expected farrowing date to allow them to adapt to the crate environment before parturition. Moving too late raises stress immediately before farrowing. Some operations move at day 84 (30 days before) to maximize crate adaptation time in herds where stress-induced problems are common.

Commercial sows in modern operations average 13-15 total born per litter, with 12-14 born alive. Gilt litters average 1-2 piglets fewer than mature sow litters. Genetic selection has pushed total born numbers higher in recent decades, but pre-weaning survival rate is the limiting factor in litters above 14-15 total born.

Most sows return to estrus 3-7 days after weaning. Sows weaned in good body condition (body condition score 2.5-3.5 on a 1-5 scale) cycle back faster than thin sows. Underfeeding in late lactation lengthens the post-weaning interval significantly and reduces subsequent litter size.

A gilt is a female pig that has not yet farrowed her first litter. After her first farrowing she becomes a sow. Gilts have a slightly longer gestation (115 days vs 114), produce smaller first litters, and require more careful feeding management to support both pregnancy and their own continued growth. They are also more likely to exhibit first-farrowing difficulties and benefit from close supervision.