Date Full Report Received


Date Abstract Report Received



Primary Investigator:

The high prolificacy of the Meishan pig has been linked in part to the high placental efficiency (ratio of piglet weight to the weight of its placenta) displayed by its conceptuses. An early report suggested that selection for placental efficiency could be used to rapidly increase litter size. Four generations of selection in the present study resulted in significant deviation in placental efficiency between lines, but no difference in litter size. It furthermore failed to result in changes in components of litter size that might be expected to improve litter size given more generations of selection. It is possible that in western breeds of pigs, the absence of physiological compensatory mechanisms will reduce the probability of prenatal survival as a result of selection for a reduced placental weight. Selection for increased placental efficiency is thus unlikely to result in a correlated increase in litter size.