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The cost of purchasing and maintaining a bull is substantial yet is easily overshadowed when a group of cycling female cattle fail to become pregnant and a complete calf crop is lost. Fortunately, this worst case scenario is a relatively rare occurrence but can have financial implications on a par with any unforeseen natural disaster. Especially in single‐sire breeding systems, this should be reason enough to have a breeding soundness evaluation prior to every breeding season; however, the most costly losses associated with poor fertility are much more insidious. Profit margins in the cow‐calf sector continue to shrink; therefore all producers must look for ways to improve productivity. In well‐managed herds, it is expected that 95% of the breeding females will become pregnant in a 60‐day breeding season, with 65% pregnant during the first 21 days. Anything less than this may be considered subfertility. Most mature beef bulls are expected to successfully mate with at least 25 cows, with lower ratios of one bull to 30, 35, and even 40 or more being used in an effort to improve efficiency while capitalizing on superior genetics. To achieve these goals, bulls must meet a set of standards below which subfertility is likely to occur.

The Society for Theriogenology (SFT) has developed a set of standards for bull breeding soundness examination (BBSE) based on available scientific data combined with input from veterinary practitioners. The SFT standards, including how the breeding potential of the bull is classified, differ almost unnoticeably from the standards adopted in other countries [1, 2]. The intent of this chapter is to provide an overview of the semen collection and evaluation in the bull. For a more indepth review, readers are encouraged to access a breeding soundness examination manual identified in the references and to review other chapters in this textbook.

Utilizing the SFT classification system, following a BBSE the animal may be classified as (i) a Satisfactory Potential Breeder, also known as “Passing” the BBSE; (ii) Classification Deferred; or (iii) an Unsatisfactory Potential Breeder. The BBSE focuses on three major categories: (i) physical soundness; (ii) scrotal circumference; and (iii) semen quality. To be classified as a Satisfactory Potential Breeder a bull must meet the described standards for all of the categories. Exceeding the standard in one category does not supersede failing the standard in another [1].

The number‐one reason bulls do not receive a satisfactory classification is because of semen quality, specifically, abnormal sperm morphology.