Animal Science, Department of


Date of this Version

January 2002


Published in 2002 Nebraska Beef Cattle Report. Copyright © 2001 The Board of Regents of the University of Nebraska.


Two estrous synchronization experiments were conducted on lactating cows to compare the Select Synch program with the one injection PGF- 10-day program and the CO-Synch mass AI program. The Select Synch program in both experiments produced good results. Pregnancy rates during the synchronization period were 62% and 81% for the Select Synch program compared to 49% for the PGF and 61% for the CO-Synch programs. The Select Synch program induced estrus in some noncycling cows. However, the Select Synch program requires two injections (GnRH and PGF) and about seven days of heat detection and AI breeding.