Breeding Soundness Examination of Boars
In postpubertal boars, testes should be symmetric (<1 cm difference), with each testis having a minimum length and width of 8 and 5 cm, respectively. Semen is collected with the boar mounted on a phantom or an estrous sow. As the penis is extruded, the tip (incorporating the coiled part) is grasped with a gloved hand and compressed; this stimulates full erection and ejaculation. The opening of the urethra is ~1 cm proximal to the tip of the glans, and care must be taken not to block it while applying digital pressure. The volume of semen is high, and ejaculation occurs over a long period, so semen is usually collected into an insulated container to maintain a relatively constant temperature. A filter or opened gauze sponge is fastened across the opening of the container to filter out gel and debris. Normal semen values for the boar are volume, 50–500 mL; sperm concentration, >50 × 106/mL; progressive motility, >70%; total sperm per ejaculate, >60 × 109; and percentage of morphologically normal sperm, >80%.