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Angus Journal
Copyright © 2015
Angus Journal

Overview of Synchronization Protocols

Dave Patterson offers an overview of current protocols available for synchronizing estrus of cows and heifers.

by Kasey Brown, associate editor

STILLWATER, Okla. (Oct. 8, 2014) — There are plenty of challenges in the U.S. beef industry, but there are opportunities, as well, and Dave Patterson was quick to highlight a few. Reproductive technology works and is on the shelf ready to use. Increasing domestic and global demand for high-quality beef are also opportunities, as are a host of marketing incentives that add value.

“A reproductive tract score is the most underutilized tool in reproductive management,” said David Patterson.

The University of Missouri animal science professor spoke to attendees of the 2014 Applied Reproductive Strategies in Beef Cattle (ARSBC) symposium in Stillwater, Okla., Oct. 8-9.

Time and labor are the biggest inhibitors of reproductive technology use, he cited. However, the benefits can outweigh the labor and time costs. Increased profits can result when more females in the herd calve in the first 21 days of the calving season. He said that high-production herds see 61% of the calves born by Day 21, 85% by Day 42 and 94% by Day 63.

Heifers that conceive earlier during their first breeding season stay in the herd longer and produce more pounds of beef throughout their lifetime, he added. However, cattlemen must manage their heifers correctly to achieve best reproductive results, reaching an optimal target weight by breeding season and making use of management tools such as reproductive tract scores (RTS), pelvic measurements, estrus synchronization and calving-ease sire selection.

“A reproductive tract score is the most underutilized tool in reproductive management,” Patterson asserted. An RTS, scored from 1 to 5, with 5 being the best, scores cycling status, uterine horn tone and ovary development. Heifers should be evaluated for RTS four to six weeks before breeding or two weeks before synchronizing estrus. He recommended waiting to begin synchronization until at least 50% of your heifers have an RTS of 4 or 5.

When evaluating the success by RTS to fixed-time artificial insemination (FTAI) for 14,510 heifers from the Missouri Show-Me-Select Replacement Heifer Program, the pregnancy rate differed dramatically. Patterson explained that the group of heifers categorized with an RTS of 1 recorded a pregnancy rate of 10%. Those scored with an RTS 2 had a 32% pregnancy rate; those with an RTS 3, 46%; RTS 4, 50%; and RTS 5, 53%.

“Choosing a protocol for use in synchronizing heifers prior to fixed-time AI should include consideration of the pretreatment estrous cyclicity status of heifers four to six weeks before breeding. Careful attention to protocol compliance, specifically product administration and timing of insemination are critical determinants of success,” he said.

For cows, he added, “Choosing a protocol for use in synchronizing beef cows should include consideration of the age of the cows, the average number of days postpartum at treatment administration and body condition.”

When considering a choice between the five-day and seven-day protocols, he said that both protocols work effectively in postpartum cows, with evidence of up to a 3% advantage of the five-day protocol. However, he cautioned that cattlemen should consider the increased labor and treatment costs associated with the five-day protocol.

Patterson spoke during Wednesday’s ARSBC session focused on reproductive management. For more information, visit the Newsroom at to view his PowerPoint, read the proceedings or listen to the presentation.

Comprehensive coverage of the symposium is available online at Compiled by the Angus Journal editorial team, the site is made possible through sponsorship by the Beef Reproduction Task Force.

Editor's Note: This article was written under contract or by staff of the Angus Journal. To request reprint permission and guidelines, contact Shauna Rose Hermel, editor, at 816-383-5270.