Uterine contractions

They are a series of spasms that happen in the uterus (womb) on certain occasions. They basically happen during the farrowing in order to help the sow to expel the piglets, and during the natural mating or the artificial insemination of the sow, to help the semen deposited in the uterus to move forward towards the place where the spermatozoa will meet the ova.