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Copyright © 2015
Angus Journal

Synchronization Protocols for Cows

by Kindra Gordon for Angus Productions Inc.

SAN ANTONIO, TEXAS (Jan. 28, 2010) — “Forty years ago the beef industry did not have any of the products for synchronization that we have today,” pointed out University of Florida associate professor Cliff Lamb as he addressed participants at the Applied Reproductive Strategies in Beef Cattle (ARSBC) workshop hosted in conjunction with the 2010 Cattle Industry Annual Convention and NCBA Trade Show in San Antonio, Texas.

There is more semen available today to AI beef cows than ever before, Lamb noted. “The progress in the industry has been amazing to me. Many of the synchronization systems available today have eliminated the need for heat detection.”

Traditionally, 5%-8% of beef females are bred by artificial insemination (AI), but it is moving closer to 12%-14% today, Lamb said. “I credit that to the fixed-timed AI protocols.”

Before giving an overview of some of the most applicable synchronization protocols, Lamb said it is important to understand three definitions:

He emphasized that in comparing protocols, pregnancy rate is the best indicator of reproductive success. As well, to achieve optimal pregnancy rates with estrus synchronization, cows should be in good body condition (BCS ≥5) and treatments should be initiated only when cows are at least 50 days postpartum. Lamb said protocols that utilize the CIDR® can help kick-start non-cycling cows, but no protocol can help get thin cows bred.

Lamb provided an overview and research on the following synchronization systems:

Lamb discussed the advantages and drawbacks for each system. For instance, in only using the prostaglandin injections, he pointed out that it only works in females that are cycling. “So it has lost some favor,” he said. Lamb also said a drawback of the Select Synch and CO-Synch systems [which use gonadotropin-releasing hormone (GnRH) followed by a prostaglandin injection] is that 10%-20% of females will show heat before the prostaglandin injection is given, so heat detection becomes important.

That said, Lamb showed research that indicates systems that use timed AI can have increased pregnancy rates. As one example, the CO-Synch system — in which a second GnRH is given and cows are AI’d at the same time — had no difference in pregnancy rate compared to the Ovsynch system where the second GnRH injection was given and cows were bred 48 hours later.

“It’s a no brainer to use the CO-Synch system so you don’t have to run the cows through the chute 48 hours later,” Lamb said.

In discussing the CIDR, Lamb said it can be a useful tool in the Select Synch and CO-Synch systems to prevent females from coming into heat early — as well as to kick-start non-cycling cows.

“Adding the CIDR increases pregnancy rates by about 11%,” Lamb said. He also shared information from a large study that showed that heat detection alone will miss about 10%-12% of cycling cows. Thus he suggested, “Heat detection followed by timed AI or clean-up timed AI is better than heat detection alone.”

Lamb also compared the seven-day Co-Synch and five-day CO-Synch systems, each using the CIDR and timed AI. Lamb said there are pros and cons with each system. Presently, the seven-day system appears to be the most used, but he said more and more producers are embracing the five-day system.

“You have to run the cows through the chute twice in one day with the five-day system,” he explained, but because cows are already separated from calves, it does not appear to pose too much concern for producers.

In concluding his presentation, Lamb said the bottom line is that several studies are showing very good pregnancy rates with timed AI (58%-63%). Results of the most recent CIDR based studies indicate that for a timed-AI (TAI) protocol the five- or seven-day CO-Synch + CIDR protocols yield the most impressive pregnancy rates for a TAI protocol, whereas the Select Synch + CIDR and TAI treatment yields the best overall pregnancy rates.

As an additional point, Lamb talked about a tighter calving distribution by using synchronization systems, and he said he wanted to dispel the myth that the CO-Synch plus CIDR system delays estrus and changes calving distribution. “That is not true,” Lamb said, citing a recent study he completed that showed it does not delay estrus.

View Lamb’s Power Point presentation for a copy of the Protocol Sheet highlighting specifics for each of the recommended synchronization systems listed above.

Click here for speaker's PowerPoint. (1.1 MB pdf)
Click here for speaker's proceedings. (316 KB pdf)
Click here for audio to presentation. (5.9 MB mp3)

The ARSBC program was developed by the Beef Cattle Reproduction Task Force to improve understanding and application of reproductive technologies, including AI, estrus synchronization and factors affecting male fertility. For additional coverage — including summaries, proceedings and audio for each presentation — visit the newsroom at For API coverage of the Cattle Industry Convention, visit the newsroom at

Editor’s Note: This article is available as a news release to redistribute per an agreement between the symposium hosts and Angus Productions Inc. Click here to submit a request for a high-resolution photo of the speaker.

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