Bull Behavior, Sex-Drive and Management

Introduction Reproductive performance has greater impact on beef economic returns than does either growth rate or product quality (Trenkle and Wilham, 1977). In most cow-calf operations, females still conceive via the natural breeding bull (Godfrey and Lunstra, 1989). Thus the reproductive capabilities of bulls are of paramount importance. These capabilities are largely influenced by one or more of the following factors: a) semen quantity and quality, b) libido and mating ability and c) social interactions (dominance effects) in the breeding pasture. In addition, bull performance is limited by the fertility threshold of the female herd. The breeding soundness examination of bulls (BSE), as recommended (Society for Theriogenology, 1976), is useful in identifying bulls which have physical problems, or poor semen quality. However, other problems do not become apparent until bulls are exposed to some form of mating ability assessment (Blockey, 1975). In many cases, bulls receive no form of assessment prior to sale or use (Godfrey and Lunstra, 1989).