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

"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 < 0.02; 0 mg-60%; 1 mg-45%; 2 mg-63%; 4 mg-40%) vs a positive linear effect on cow pregnancy rates (PR) (P < 0.05; 0 mg-46%; 1 mg-53%; 2 mg-55%; and 4 mg-63%). Inclusion of a timed Al improved PR in cows not observed in estrus. There were no differences in days to emergence and ovulation of a new follicular wave, ovulation rate and ovulated follicle size when EB (0 vs 4 mg; 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."

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Animal Sciences

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Steckler, Teresa Lynn

Contributors dc:contributor

• Darrel J. Kesler

• Agriculture, Animal Culture and Nutrition

Language dc:language

eng

Identifier

(MiAaPQ)AAI3086186

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/83559