Sow Nutrition, Uterine Contractions, and Placental Blood Flow during the Peri-Partum Period and Short-Term Effects on Offspring: A Review

Abstract

The birth process is a crucial event for piglet survival. Along with increasing litter sizes, not only has the duration of parturition increased, but placental blood flow per piglet has reduced and placental area per piglet has become smaller, making these piglets more susceptible for hypoxia. Diminishing the risk of piglet hypoxia by either reducing the total duration of parturition or increasing fetal oxygenation may reduce the incidence of stillbirth and early post-partum mortality. This review discusses options to do so by nutritionally supporting the sow in the final pre-partum period, after discussing the role of uterine contractions and placental blood flow. Providing sufficient energy seems to be a logical first step, but also other nutrients needed for uterine contractions, such as calcium, or enhancing uterine blood flow by using nitrate seem promising. These nutrient requirements may depend on litter size.

Keywords: energy requirements; parturition; placental blood flow; sow; uterine contractions.

Figure 1

Myometrial contractions in the sow 12, 5, and 1 h pre-partum during spontaneous parturition (* indicate the birth of a piglet) and during the placentae expulsion, measured by two stain gauges implanted in each uterine horn as adapted from Maffeo et al. [15].

Figure 2

Relationship between average litter size and average duration of parturition (stage 2, expulsion of piglets) based on averages of 15 studies conducted over the last 18 years [12,14,17,46,47,57,58,59,60,61,62,63,64,65,66].

Figure 3

Relationships between farrowing and placental characteristics on piglet vitality, incidence of stillbirth and pre-weaning mortality, and potential roles of maternal nutrients on these relationships. Dotted lines indicate a negative effect. Grey boxes will be discussed in current paragraph.

Figure 4

Energy requirements of sows on the last day of gestation, the day of farrowing, and day 1 and 2 of lactation, adapted from [59], including estimated energy requirements for additional heat loss, nest building behaviour and farrowing [81]. ME = metabolizable energy.