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

Steckler, Teresa Lynn

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https://hdl.handle.net/2142/83559 Copy

Description

Title

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

Author(s)

Steckler, Teresa Lynn

Issue Date

2003

Doctoral Committee Chair(s)

Darrel J. Kesler

Department of Study

Animal Sciences

Discipline

Animal Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

Agriculture, Animal Culture and Nutrition

Language

eng

Abstract

"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."

Graduation Semester

2003

Type of Resource

text

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http://hdl.handle.net/2142/83559

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