COLUMBIA, Mo. – As breeding seasons for seasonal pasture-based dairy herds and beef cows approach, it might be time to consider if a new estrus synchronization protocol developed by the University of Missouri could benefit your operation.

Getting cows pregnant in beef herds and seasonal grazing dairies is critical for these operations, said MU Extension dairy specialist Stacey Hamilton and Scott Poock, MU associate extension professor of veterinary medicine.

Jordan Thomas, assistant extension professor of animal sciences, developed a protocol for synchronization of estrus among postpartum cows in 2018. Over the past two years, the protocol, called 7&7 Synch, has been effective in trials in both grazing and confinement systems, said Hamilton and Poock.

Notably, the protocol has been used on the grazing herd at Mizzou’s Foremost Dairy for the past two years with greater than 70% first-service conception rates. Trials among other herds have also shown success, though results vary due to different lengths of calving windows in previous years, said Hamilton.

“The 7&7 Synch protocol has the potential to be more effective than the commonly used Pre-Synch Ovsynch protocol in increasing first-service conception rates among mature cows,” said Hamilton. “The rate of mature cows that became pregnant after first service was more than 40% higher when using the 7&7 Synch protocol than the Pre-Synch Ovsynch.”

The 7&7 Synch protocol involves only three interventions while the PreSynch Ovsynch protocol requires six, so it saves time catching the cows, said Hamilton. However, 7&7 Synch requires the use of a CIDR, while PreSynch Ovsynch does not.

Hamilton and Poock stress the importance of conducting more trials to confirm its success.

7&7 Synch protocol

Day 0: Administer prostaglandin (PGF2a) and insert a CIDR.

Day 7: Administer GnRH.

Day 14: Administer PGF2a again and remove the CIDR. Ovulation will now occur, and you may artificially inseminate 66 hours later.

For more information, the MU Extension publication “7 & 7 Synch: An Estrus Synchronization Protocol for Postpartum Beef Cows” (G2023) is available for free download at