Beef Bull Monitoring Research Project

Participate in this study and find out if your bulls are working full time.

Reproduction is a primary determinant of cow calf production efficiency. Breeding soundness exams (BSE) are helpful in identifying bulls with poor fertility prior to the breeding season. However, BSEs are not reliable in identifying the potential for breeding impediments that develop during the breeding season such as injury or foot rot which can have devastating effects on pregnancy rates. In addition, BSEs do not adequately evaluate libido and mating ability of bulls which has been shown to directly impact pregnancy rates.

In an effort to identify breeding impediments that may occur during the breeding season and measure the libido of bulls in multiple sire pastures, Ohio State University Cattle Reproductive Professor Dr. Alvaro Garcia-Guerra has initiated a research study that you are invited to participate in. If you have a minimum herd size of 50 cows and run at least 2 bulls, here are the basics of how it will work:

Before breeding begins:

  • There will be an initial visit to address questions and concerns, walk pastures, and discuss options.
  • At least 10 days prior to the start of breeding, research team will perform an initial BSE on your bulls, fit animals for devices (one GPS collar and one accelerometer ear tag), and gather preliminary data.

During breeding:

  • Turnout of bulls as you would any breeding season.
  • Daily (whenever possible) monitoring of bulls to identify possible lameness or other issues during breeding (performed by the producer). Record keeping of health issues, pasture changes, etc.
  • Twice weekly visits by research team to observe breeding behavior, check on devices, and locomotion score bulls (just visual in the pasture).
  • If a bull develops any health problem, we ask that you record the observation in the daily survey and notify us immediately. The research team/local veterinarian will assess the severity and provide a full diagnosis of the problem.

After Breeding:

  • At the end of the breeding season bring bulls through the chute to remove the sensors.
  • Pregnancy check 35-60 days following the breeding season (performed by research team).

For more information about participating in this study, contact Dr. Alvaro Garcia-Guerra at The Ohio State University Department of Animal Sciences by email at or by phone: 1-608-770-9138, or see this project summary sheet.