Bull libido/serving capacity.

Bull libido, or sex drive, is a measurable trait with a large genetic component. It also represents an important aspect of bull reproductive performance, with positive effects on herd pregnancy rates and their patterns. Comparative, quantitative assessment of this trait requires a formalized testing procedure such as a test for libido or serving capacity score. Such tests are useful not only for obtaining quantitative information, but also for the detection of physical and pathologic problems that may interfere with normal bull mating ability. These tests should be conducted in such a manner that animal welfare is not unnecessarily compromised. The quantitative results should be interpreted with caution, especially when young, inexperienced bulls or those of Bos indicus breeds are being assessed. Libido does not necessarily work in concert with other traits known to separately influence bull fertility (e.g., BSE traits and social dominance). Until a single procedure is found that can adequately assess all of these factors, optimal bull appraisal requires separate evaluation of each of these factors.