Bilateral luteal maintenance in unilaterally pregnant pigs with infusions of embryonic extracts

Thirty unilaterally pregnant gilts with bilateral corpora lutea received infusions three times daily into a surgically isolated, nonpregnant uterine horn from d 12 through d 19 after mating. The infusions consisted of either saline alone or embryonic extracts in saline which were either untreated, heat-treated or charcoal-absorbed. The extracts were from porcine embryos, embryonic membranes and fluids between d 16 and 25 of pregnancy. While only 20% of the gilts infused with saline alone and none of those infused with charcoal-absorbed embryonic extracts maintained pregnancy to d 19, 100 and 83% of the gilts infused with untreated and heal-treated embryonic extracts, respectively, were pregnant on d 19. Similar treatment effects were observed for the incidence of bilateral luteal maintenance. No gilts receiving infusions of either saline or charcoal-absorbed embryonic extracts exhibited bilateral luteal maintenance. However, 67% of the gilts infused with untreated embryonic extracts and 67% of those infused with heated extracts had bilateral luteal maintenance on d 19. Additionally, the weights and progesterone concentrations of corpora lutea adjacent to the infused uterine horns were not different (P less than .05) from those of the corpora lutea adjacent the to pregnant uterine horns in gilts with bilateral luteal maintenance.