Improvement of pregnancy rate by intrauterine administration of dexamethasone and recombinant human leukemia inhibitory factor at the time of embryo transfer in cattle

摘要

Bovine embryos (day 5) were cultured to day 10 with or without 100 ng/mL PGF2 alpha in medium supplemented with control; 100 nM Dex; 1,000 U/mL recombinant human leukemia inhibitory factor (rhLIF); or Dex+rhLIF. Although the rates to development to the blastocyst were not significantly different among groups, the hatching rate after additional culture with Dex +/or rhLIF was significantly higher in all supplemented groups than the control (p < 0.05). In the presence of PGF2 alpha, the hatching rate was significantly restored in all supplemented groups relative to the group treated with only PGF2 alpha and the control (p < 0.05). Embryo transfer (ET) was performed with blastocysts (day 7). PGF2 alpha levels of control recipient cows were significantly higher in the circulatory blood samples collected 60 min after ET than in samples collected 60 min before ET (p < 0.005), and were decreased in cows injected with loading medium supplemented with Dex+rhLIF (p < 0.005). Pregnancy rate was significantly higher in the ET group that received supplemented embryo-loading medium than in the non-supplemented control (p < 0.05). The intrauterine administration of Dex and rhLIF at ET prevented increased PGF2 alpha in circulatory blood and resulted in enhanced pregnancy rate.