Programs for fixed-time artificial insemination in South American beef cattle.

Fixed-time artificial insemination (FTAI) has been widely applied in South America within the last 20 years for the genetic improvement of commercial beef herds. Most FTAI treatments for beef cattle used in South America are based on the use of progesterone (P4) releasing devices and estradiol to synchronize follicle wave emergence, with pregnancies per AI (P/AI) ranging from 40 to 60%. More recent protocols focusing on extending the interval from device removal to FTAI (i.

Alternative programs for synchronizing and resynchronizing ovulation in beef cattle.

Fixed-time artificial insemination (FTAI) has been regarded as the most useful method to increase the number of cows inseminated in a given herd. The main treatments for FTAI in beef cattle are based on the use of progesterone-releasing devices and GnRH or estradiol to synchronize follicle wave emergence, with a mean pregnancy per AI (P/AI) around 50%. However, more recent protocols based on GnRH (named 5-day Co-Synch) or estradiol (named J-Synch) that reduce the period of progesterone device insertion and extend the period from device removal to FTAI have been reported to improve P/AI in beef cattle.