Successful reproductive management of the beef cow herd includes having a high percentage of cows calving during the first 21 days of the calving season as well as a high percentage of cows calving. Nutrition, herd health , crossbreeding systems and evaluation of bulls for reproduction potential are all management areas that need attention in attaining these goals. Current guidelines for evaluating the reproductive potential of bulls include a 'physical exam, measuring scrotal circumference and evaluating semen (Breeding Soundness Exam , Society for Theriogenology). When conducted by an experienced person , these are relatively simple procedures that should be considered when culling bulls of low reproductive potential. Research during the last 10 years has demonstrated that there is tremendous variability among beef bulls for their ability and desire to mate (libido or sex drive). Bulls that are rated "satisfactory" in a Breeding Soundness Exam may achieve unacceptable pregnancy rates due to lack of libido. Libido is much more difficult to evaluate than the other factors that affect the reproductive performance of bulls. Social dominance or "peck order" also affects the breeding performance of bulls used in multi-sire breeding groups.
Number of Pages
South Dakota State University
Copyright © 1984 South Dakota State University
Pruitt, R. J., "Bull Behavior and Pregnancy Rates" (1984). South Dakota Cow-Calf Field Day Proceedings, 1984. 3.