Placental characteristics of German Landrace sows and their relationships to different fertility parameters

The placenta is the central foetal organ that ensures a sufficient exchange of nutrients and metabolites for adequate foetal growth. Specific data profiles for placental characteristics from modern pig lines with high fertility and today's genetics are not currently available. This study focuses on describing the placental weight and size of German Landrace pigs and any subsequent relationship to litter number and important fertility parameters for these sows. As a basis for data collection, 55 litters from primi- and multiparous German Landrace sows with a total of 832 piglets were used. From these births, 766 placentas were recovered and weighed, with their lengths measured and the placental efficiency per litter also calculated. Mean placental weights ranged from 179 +/- 60 to 422 +/- 96 g between litters, and the mean length was between 61 +/- 12 and 145 +/- 19 cm. The placental efficiency was at a level of 5.1 +/- 0.7. The investigated parameters were only slightly affected by the litter number (r = 0.3), and the means did not significantly differ between different litter numbers. With increasing litter size, the piglet weights and placental lengths were significantly decreased (r = -0.4 and r = -0.3), possibly due to limited uterine space. However, litter size had a strong positive correlation with the total litter placental weight (r = 0.7); therefore, in this study, the placental efficiency was not affected by a higher number of piglets per sow. Higher means for placental weights (r = 0.7) and lengths (r = 0.7) in a particular litter significantly improved the piglet birth weights. The reported variability in placental characteristics between litters suggests that there is an opportunity to selectively breed for improved piglet weight and homogeneity and thus improved piglet health and survival.