Intrauterine position effects in female swine: Subsequent reproductive performance, and social and sexual behavior

Uterine position, relative to the sex of adjacent fetuses, is known to affect the subsequent behavior and reproductive performance of rodents. This experiment was designed to determine if similar effects are present in female swine. Donor sows were slaughtered at Day 112 of gestation, the uteri removed and piglets delivered manually. Uterine position was recorded for each pig as between 2 females (0M, n=16), between a male and a female (1M, n=25) or between 2 male fetuses (2M, n=17). Females were reared in heterosexual littermate groups until 120 days and thereafter in unisexual groups of six. Females were checked twice daily for estrus using a mature boar beginning on Day 175. 2M females tended ( P