Methods to Synchronize Estrus, Enhance Pregnancy, and Rescue Embryos in Cattle

140 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2003.Enhancing reproductive efficiency in beef and dairy herds can be accomplished through synchronization regimes. Synchronization of heifers and cows with 0, 1, 2 or 4 mg of estradiol benzoate (EB) at the onset of the CIDR/PGF 2alpha protocol resulted in a cubic effect on heifer conception rates (P 0.05) was administered. More follicles classified as "maintained" were observed in the 0 mg group (P = 0.01; 0 mg-53%; 4 mg-0%). The effect of an IPI during and after synchronization with COSynch was determined; PR were not affected by early weaning (EW) or the EWxIPI interaction (P > 0.05), but was affected by IPI administration (P = 0.04; COSynch-32.4% vs COSynch+IPI-44.5%). Supplemental P4 during early gestation (d 5 to 14) did not improve PR (P = 0.91). The effect of an IPI during synchronization or at ET was examined; the transfer rate was 92% and PR for anestrous cows differed (P 0.05; OvSynch-50% vs OvSynch+IPI-59%). Administration of an IPI at ET did not improve PR (P = 0.55). New functional CL induced by hCG in cows that had spontaneous CL regression subsequent to ET resulted in the rescue of 3/6 pregnancies. Inclusion of a CIDR during synchronization in dairy cows with or without ovarian cysts (COD) was examined. Day 35 and 84 PR were: OvSynch+P4-81% and 67%, OvSynch-61% and 56%; OvSynch+P4+COD-44% and 33%; and OvSynch+COD-40% and 22%, respectively. All OvSynch+P4+COD (100%) cows ovulated versus 82% of the OvSynch+COD. The presence of cystic structures on d 28 (P 0.3; OvSynch+P4-6% vs OvSynch+P4+COD-22%). The novel data reported herein demonstrates that reproductive efficiency can be enhanced in beef and dairy herds through novel synchronization regimes.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD