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Copyright © 2015
Angus Journal

Get the Most Cows and Heifers Pregnant

Heat detection, inseminator efficiency, and fertility of the herd and semen are critical factors.

by Troy Smith for Angus Journal

STAUNTON, Va. (Oct. 15, 2013) — Fertility plays a major role in the success of any breeding program, whether it involves artificial insemination (AI) or natural service. In a presentation to the Applied Reproductive Strategies in Beef Cattle (ARSBC) Symposium hosted Oct. 15-16 in Staunton, Va., South Dakota State University (SDSU) animal scientist George Perry talked about factors influencing fertility of beef cows and heifers to be bred by AI. Perry’s comments focused on what he considers critical issues, including the percentage of animals detected in standing estrus and inseminated, inseminator efficiency, fertility level of the herd, and fertility level of the semen.

George Perry

“We don’t want to stress animals right after AI,” emphasized George Perry of SDSU. “It’s a horrible time for females to experience stress from vaccination, shipping or nutrient deficiency."

With natural service, detection of females in standing estrus, or heat, is the bull’s job. With AI, this critical duty falls to the cattle manager, said Perry. It is common for visual observation to take place in the early morning and again at night.

“To determine the best time to inseminate an animal, visual heat detection really needs to be done more than twice per day,” advised Perry.

He cited studies showing that heat detection could be increased by 10% when females were observed three times each day, adding one more observation at mid-day. Heat detection was improved by 19% when performed four times per day, or every six hours.

Admittedly, heat detection by visual observation is a time-consuming chore. Perry said heat-detection aids, such as marker animals or heat-detection patches, can help. However, increased visual observation, in addition to the use of estrus-detection aids, could improve fertility by determining the most appropriate time for insemination.

To address the question of whether synchronization protocols can decrease or increase fertility, Perry said studies indicate no reduction in fertility and some protocols can result in an increased chance to become pregnant during the first few days of the breeding season and more opportunities to conceive during the breeding season.

Perry also discussed fixed-time AI (FTAI), involving synchronization protocols that allow for all females to be inseminated at a predetermined time, thus eliminating the need for heat detection.

“Fixed-time AI is a practical alternative to heat detection,” stated Perry. “If you are not doing a good job of heat detection, using fixed-time AI may actually improve your conception rates.”

Discussing inseminator proficiency, Perry reminded managers to observe proper semen-handling practices, follow recommended thawing procedures, use proper hygiene and deposit semen correctly and within 15 minutes of thaw.

Perry said herd fertility level may be the hardest factor to evaluate but includes cycling status, compliance with protocols, embryonic mortality, body condition (nutrition level), and disease status. Though often overlooked, various stress factors can influence fertility. These include changes in diet. Stress experienced soon after insemination can also jeopardize embryo survival.

“We don’t want to stress animals right after AI,” emphasized Perry. “It’s a horrible time for females to experience stress from vaccination, shipping or nutrient deficiency.”

Perry spoke during Tuesday's ARSBC session focused on managing factors to improve pregnancy rates. Visit the Newsroom at to listen to his presentation and to view his PowerPoint slides and proceedings paper.

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.