Department of Animal Science


Date of this Version



2016 Nebraska Beef Cattle Reports


© The Board Regents of the University of Nebraska. All rights reserved.


To evaluate the ideal number of bulls to use following estrus synchronization and artificial insemination (AI), research reporting AI and final pregnancy rates and bull to female ratio in Bos taurus cattle was reviewed and summarized. Pregnancy rate means were weighted based on the number of females in each study. Final pregnancy rates for a normal bull to female ratio (1:20 to 30) in a natural service setting were 87.8%. In comparison, final pregnancy rates following estrus synchronization and AI for a normal, intermediate (1:31 to 49), and half the number of bulls (1:50 to 60) were 87.8, 82.6, and 89.2%, respectively.

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