Testicular degeneration and libido loss in beef bulls experimentally inoculated with Anaplasma marginale.

Four sexually mature virgin beef bulls were inoculated with whole blood from a known Anaplasma marginale carrier. All four bulls became infected and experienced some degree of anemia and testicular degeneration, while uninoculated controls remained normal. Testicular degeneration was confirmed by electron microscopy, histopathology, and semen evaluation. Further observations established that the inoculated bulls exhibited a loss of libido, while controls reacted in a normal manner to a cow in estrus. Anaplasma marginale was not present in semen of inoculated bulls.