Ultrasonographic and other testicular characteristics of Holstein bulls revisited

The testes of bulls in an artificial breeding unit were examined with low frequency (1.6 and 2.25 MHz) transducers to determine if acoustical impedance could be used to detect bull differences in testicular tissue. The initial studies accompanied measurement of the linear dimensions and circumference of the testes with simple calipers and tapes to estimate size. Simple instruments proved to provide testicular size information that was more accurate and more easily obtained than by ultrasonography. Subsequent studies dealt with spermatogenic elements. Internal characteristics of the testes of 10 normal young bulls measured by ultrasonography were similar and were not significantly correlated with semen characteristics. Ultrasonograms on the testes of 68 bulls 20 to 144 months old differed, particularly associated with age. There was more dense tissue distributed in the testicular parenchyma of older bulls. Twenty-six bulls that had preslaughter ultrasonic analysis of the testes were classified into two groups after slaughter on the basis of normal or high proportions of fibrous testicular tissue. An independent analysis of the ultrasonograms concurred 81% of the time with the postmortem findings. While ultrasonography has greatly aided the understanding of many events in reproductive development and sexual function, it appears that its capabilities of providing unique information on internal testicular characteristics may be limited to special cases, such as old bulls wh