Alternative programs for synchronizing and resynchronizing ovulation in beef cattle.

Area of Science:

• Reproductive biology in livestock
• Animal science and breeding
• Veterinary medicine

Background:

• Fixed-time artificial insemination (FTAI) is crucial for increasing insemination numbers in beef herds.
• Current FTAI protocols often use progesterone-releasing devices with GnRH or estradiol, achieving a mean pregnancy per AI (P/AI) of approximately 50%.

Purpose of the Study:

• To review recent advancements in FTAI protocols for beef cattle.
• To highlight methods that improve pregnancy per AI (P/AI) and enable sequential inseminations.

Main Methods:

• Evaluation of synchronized ovulation protocols using GnRH (5-day Co-Synch) or estradiol (J-Synch).
• Analysis of protocols that modify progesterone device duration and interval from device removal to FTAI.
• Assessment of resynchronization treatments for nonpregnant cows to allow for a second FTAI.

Main Results:

• Newer protocols like 5-day Co-Synch and J-Synch show potential for improved P/AI in beef cattle.
• Sequential insemination strategies, including resynchronization, can achieve high P/AI and reduce reliance on clean-up bulls.
• FTAI protocols have significantly advanced AI adoption in beef cattle by removing the need for estrus detection.

Conclusions:

• Optimized FTAI protocols are key to enhancing reproductive efficiency in beef cattle operations.
• Advanced synchronization and resynchronization strategies offer significant benefits for breeding programs.
• FTAI simplifies AI implementation in beef herds, leading to improved reproductive outcomes.