The exam includes a complete physical, scrotal measurement and semen evaluation. During the physical examination a veterinarian observes the bull as he moves, looking for inadequacies in movement, leg conformation and general body condition. A bull's eyes and teeth are examined. The lungs and heart are evaluated and a rectal exam is performed to determine the health of internal reproductive organs. Injury and disease to the penis is observed and the testes and epididymis are palpated for evidence of degeneration or inflammation.
Scrotal circumference is measured and is a good indication of semen producing ability.
Larson says all testicles produce the same number of sperm per gram of testicle. Thus, a bull with bigger testicles will produce more sperm. Because of the difference among testicular sizes, daily sperm production among bulls varies from three billion to more than eight billion. Research shows increased scrotal circumference also relates to earlier puberty in daughters. After the physical examination and scrotal measurement, a semen sample is collected either with the aid of an electro-ejaculator, massage of the prostate or use of an artificial vagina and a mount animal.