The breeding soundness examination (BSE) involves a complete and systematic evaluation of the reproductive potential of a given male, including mating ability and libido, general physical examination and inspection of the genital organs, and assessment of sperm production and quality. The BSE is not a direct evaluation of fertility: this can only be confirmed by the successful production of offspring after breeding a fertile female. The specific male animal must be properly identified, and a detailed history is important because sub- or infertile males might require more exhaustive evaluation. The evaluation of mating ability and libido is possible only when collecting semen via artificial vagina or manual stimulation in the presence of a female in estrus. Therefore, mating ability is seldom evaluated in bulls and rams for routine BSE in which semen is typically collected via electroejaculation.

The components of semen quality evaluation are: 1) semen volume and sperm concentration, which allow for the calculation of the total number of sperm in the ejaculate; 2) sperm motility, including gross motility (ruminants only) and percent individual sperm motility (total and progressive) of a diluted sample; and 3) the percent morphologically normal sperm. A Romanowsky-stained cytology sample also allows for the evaluation of red (hemospermia) or white (pyospermia) blood cells in the ejaculate. When collecting semen from ruminants via electroejaculation, the sperm production potential is estimated by measuring scrotal circumference. Scrotal circumference is correlated with daily sperm output and therefore the serving capacity of a bull or ram (ie, number of females he can settle in a limited time).

After the BSE is complete, the male is classified as a satisfactory, questionable, or unsatisfactory prospective breeder. An animal with physical defects that may be inherited (including cryptorchidism) should be declared unsatisfactory. The following are guidelines for the BSE in each domestic species.

Last full review/revision July 2011 by Sylvia J. Bedford-Guaus, DVM, PhD, DACT