Beyond Bull Breeding Soundness Evaluations ( BSEs )

The capability of bulls to distribute their genetics is dependant upon their fertility, whether they are used for natural breeding or A.I. In turn, herd reproductive performance has been shown to have a greater impact on economic returns than either growth rate or product quality (Wiltbank 1994). Here, chute-side math indicates it takes approximately 5 generations (15 years) using bulls of 10% superior WWT EPDs, to have the same impact on total herd lb weaned as a 5% increase (85-90%) in weaning rate. Most cattle throughout the world are still bred naturally. However, breeding bulls differ markedly in their reproductive capabilities. Conservative estimates indicate at least 20% of unselected bulls are sub-fertile or infertile. Procedures used to evaluate bulls have been shown to be effective in identifying many of these sub-fertile and infertile bulls. The procedures involved in such evaluations are remarkably consistent throughout the world. In North America, the Society for Theriogenology (SFT) recommends a standardized procedure that has been periodically modified (Chenoweth et al, 1992).