Evaluation of timed Artificial Insemination as a breeding strategy to improve reproductive efficiency and calf crop

Principal Investigator: Anna Denicol

The use of artificial insemination (AI) in beef production offers the opportunity to accelerate herd genetic gain, improve reproductive performance and calf weaning weights.

Timed-AI programs employ synchronization of ovulation to avoid estrus detection, allowing 100% service rate. These programs can yield 75% pregnancy rate with two services within 33 days.

Replacing natural service (NS) by TAI means reducing the need for bulls in the herd and the risk of transmission of costly venereal diseases; however, costs associated with TAI must be considered including labor, hormones, semen, and infrastructure.

A direct comparison between TAI and NS has not been performed in CA rangeland grazing cows, meaning that our beef industry could be missing an opportunity to improve profitability.

The goal of this project is to evaluate performance of TAI and NS in a typical rangeland grazing herd. Cows in the TAI group will receive hormones for synchronization and two inseminations within 33 days followed by natural service during the last 15 days of the breeding season. Cows in the NS group will be exposed to bulls of proven fertility for the entire breeding season (60 days).

Pregnancy rate at 30 days and at the end of the season, calf birth, weaning weight and weight gain, and reproductive status of cows in the next breeding season will be evaluated and used to calculate the costs and benefits of each breeding strategy.

Results of this project will be valuable to inform producers about the efficiency and economic advantage of both breeding strategies.