Abstract Monsi, A., Cecil, H.C. and Bakst, M.R. 1993. Aspects of biological changes in breeder toms after treatment with subcutaneous cadmium injection: Study of semen characteristics. J. Appl. Anim. Res., 4: 83–90. Changes in reproductive parameters of breeder toms injected with cadmium chloride (CdCl2 2.5H2O) were studied. Each treated member of twenty-four pairs of yearling toms was given 4.5 mg Cd/kg body weight. Six birds each were subsequently killed at 0, 6, 24 and 192 h and evaluated for selected semen characteristics. Elevated (P<0.001) Cd concentration was observed in the seminal plasma of the treated toms due possibly to Cd-induced inactivation of the blood-testis barrier. However, the 5-fold increase in the Cd level hardly inflicted any injurious effect on the cellular integrity of the sperm cells since live/dead percentage of spermatozoa did not differ significantly from that of control. Among other possible mechanisms Cd sequestration could have protected the sperm cells. It is further sugge...