Value of synchronizing bull-bred cows and first-calf heifers

By Dr. Todd Bilby

For cow-calf operations, reproductive efficiency is vital to increasing profitability. Heavier calves and a more consistent calf crop can result in increased pounds of beef. The key is getting more cows pregnant in the first 21 days of the breeding season.

Merck Animal Health and Angus have teamed up to provide relevant advice and expertise to producers. In this video, Todd Bilby, Ph.D., director of cattle technical services at Merck Animal Health, answers commonly asked questions about optimizing reproductive health, including:

  • What are the benefits of a tighter calving window?
  • Should I synchronize heats if I use natural service?
  • Will I need more bull power if I utilize heat synchronization?
Dr. Todd Bilby in a Merck branded coat and hat.

Watch Dr. Todd Bilby on tighter calving windows

Take the guesswork out of breeding

ESTRUMATE® (cloprostenol injection) is the top cloprostenol on the market, proven to improve reproductive performance in both dairy and beef cattle.1 This essential reproductive tool allows for better heat detection and increased control of breeding and calving intervals.

A University of Nebraska-Lincoln study2 showed the following benefits of heat synchronizing with a single injection of prostaglandin 4.5 days (108 hours) after turning mixed-age bulls in with the cow herd:

  • More cows calved during the first 21 days
  • 20 lb heavier calves at weaning
  • Shortened breeding season from 60 to 45 days
  • Heavier, more valuable carcasses worth an additional $77 per carcass at the feedlot

One shot of a prostaglandin four to five days after turning out the bulls is the optimal protocol. However, if that protocol won’t fit your management system, one shot at turnout will still induce more cows to show heat sooner and get more cows calving during the first 21 days. Learn about what prostaglandin Merck Animal Health offers here.

Watch the video to learn more or ask your veterinarian.


ESTRUMATE IMPORTANT SAFETY INFORMATION: Do not administer ESTRUMATE to a pregnant cow unless abortion is desired. Severe localized post-injection clostridial infections have been reported; in rare instances infection has led to death. Women of childbearing age, asthmatics and persons with respiratory problems should exercise extreme caution when handling ESTRUMATE. ESTRUMATE is readily absorbed through the skin and can cause abortion and/or bronchospasms; direct contact with the skin should be avoided, and accidental spillage on the skin should be washed off immediately with soap and water. For complete safety information, refer to the product label.


  1. Animalytix, MAT May 2020.
  2. Larson DM, Musgrave JA, Funston RN. Estrous synchronization increases early calving frequency, which enhances steer progeny value. Nebraska Beef Cattle Reports. 2010;14-16.

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About the author

Todd Bilby

Cattle Technical Services,
Merck Animal Health