Developmental Impact of Uterine Crowding in the Contemporary Sow

Intensive genetic selection for increased litter size in swine has resulted in ovulation rates that exceed uterine capacity to adequately support fetal development. The gap between the number of conceptuses and the available uterine space results in low birth weight and intrauterine growth restriction (IUGR). These piglets account for an overwhelming proportion of pre weaning mortality, and those that survive exhibit a marked reduction in lifetime growth performance. In utero crowding compromises pro?tability within the American swine industry and novel strategies to minimize its effects are required. To support such innovation, there is a critical need for an improved understanding of the in utero effects of uterine crowding on the physiology of the developing pig fetus. We hypothesize that ongoing increases in litter size within the contemporary sow restrict development across the entire fetal population. This proposal aims to understand the developmental consequences and adaptations associated with uterine crowding in the contemporary pig. To accomplish this, we will utilize two surgical interventions: Unilateral oviductal ligation and unilateral hysterectomy-ovarectomy to either eliminate or exacerbate intrauterine crowding. Using this system, we will determine the impact of biological extremes of uterine space relative to the unaltered sow. We will then evaluate the developmental consequences of uterine crowding on prenatal and postnatal nutrient transport systems. Collectively this work will improve our understanding of the developmental consequences of in utero crowding and allow the development of targeted postnatal management practices to reduce the negative impact of IUGR on production. Program Area Priority: Embryonic and fetal development (including interaction between the conceptus and its uterine environment.