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Published on: July 8, 2020
Alternative programs to presynchronize estrous cycles in dairy cattle before a timed artificial insemination program.
1Department of Animal Sciences and Industry, Kansas State University, Manhattan, KS 66506-0201, USA. jss@k-state.edu
Presynchronization programs did not improve ovulation or luteal function before timed artificial insemination (TAI). The CIDR3 protocol resulted in lower pregnancy rates compared to other treatments, indicating no benefit from these presynchronization methods.
Area of Science:
- Reproductive endocrinology and artificial insemination in cattle.
Background:
- Timed artificial insemination (TAI) programs are crucial for dairy herd reproductive efficiency.
- Optimizing presynchronization protocols before TAI can enhance ovulation response and corpus luteum function.
- Previous research suggests various presynchronization strategies may impact fertility outcomes.
Purpose of the Study:
- To evaluate the efficacy of different presynchronization programs prior to a TAI protocol.
- To determine if presynchronization increases ovulation rates and establishes a functional corpus luteum before TAI.
- To compare the effects of Presynch and controlled internal drug release (CIDR) based protocols on reproductive parameters.
Main Methods:
- Five presynchronization treatments were compared: Presynch variants (Pre14, Pre12, Pre10) and CIDR-based protocols (CIDR10, CIDR3).
- A standard Cosynch TAI program served as the control.
- Hormonal (progesterone) and ovarian (follicle and corpus luteum dynamics, ovulation) assessments were conducted via blood sampling and transrectal ultrasonography.
Main Results:
- Ovulatory incidence following GnRH injections did not differ significantly among presynchronization treatments.
- Progesterone levels varied, with CIDR3 showing lower concentrations before the first GnRH and higher concentrations before the second GnRH.
- Pregnancy rates per AI were significantly lower in the CIDR3 group compared to all other treatments.
Conclusions:
- None of the tested presynchronization protocols demonstrated improvement in ovulation, luteal regression, or synchronization rates compared to the standard Cosynch TAI program.
- The CIDR3 presynchronization protocol negatively impacted pregnancy rates, suggesting it is not beneficial for TAI programs.
- Further research may be needed to identify optimal presynchronization strategies for enhancing TAI success in cattle.
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