Glucosamine supplementation during late gestation alters placental development and increases litter size

Background： During late gestation the placental epithelial interface becomes highly folded, which involves changes in stromal hyaluronan. Hyaluronan is composed of glucoronate and N-acetyl-glucosamine. We hypothesized that supplementing gestating dams with glucosamine during this time would support placental folded-epithelial-bilayer development and increase litter size. In Exp. 1, gilts were unilaterally hysterectomizedovariectomized（UHO）. UHO gilts were mated and then supplemented daily with 10 g glucosamine（n = 16） or glucose（control, n = 17） from d 85 of gestation until slaughter（d 105）. At slaughter, the number of live fetuses was recorded and each live fetus and its placenta was weighed. Uterine wall samples adjacent to the largest and smallest fetuses within each litter were processed for histology. In Exp. 2, pregnant sows in a commercial sow farm were supplemented with either 10 g glucosamine or glucose daily from d 85 of gestation to farrowing. Total piglets born and born alive were recorded for each litter. In Exp. 3, the same commercial farm and same protocol were used except that the dose of glucosamine and glucose was doubled to 20 g/d.Results： In Exp. 1, the number of live fetuses tended to be greater in glucosamine-treated UHO gilts（P = 0.098）.Placental morphometry indicated that the width of the folded bilayer was greater（P = 0.05） in glucosamine-treated gilts. In Exp. 2, litter size did not differ between glucosamine-and glucose-treated sows. However in Exp. 3, the increased dose of glucosamine resulted in a significant treatment by parity interaction（P ≤ 0.01）, in which total piglets born and born alive were greater in glucosamine treated sows of later parity（5 and 6）.Conclusions： These results indicated that glucosamine supplementation increased the width of the folds of the placental bilayer and increased litter size in later parity, intact pregnant commercial sows.