Effect of low doses of alpha-chlorohydrin on fertility and semen characteristics and binding of the drug of spermatozoa in swine.

Daily feeding of 1 mg of alpha-chlorohydrin per kg body weight to boars prevented fertility completely when the ejaculate was used for insemination. The semen charactreated than in untreated boars, but the sperm morphology was otherwise normal. In vitro addition of 5 mg/epididymal contents from the treated boars revealed normal Na+, K+ and glycerylphosphorylcholine concentrations. The movement of sperm cytoplasmic droplets was completed on all spermatozoa more distally in treated than in untreated boars, but the sperm morphology was otherwise normal. In vitro addition of 5 mg/100 ml of alpha-chlorohydrin to ejaculate boar semen completely inhibited and 2.5 mg/100 ml decreased fertility. Removal of the alpha-chlorohydrin prior to insemination partially restored fertility. 14C-alpha-chlorohydrin was shown to be more firmly bound to boar spermatozoa than 14C-carboxyinulin and could not be removed from the spermatozoa with 3 washings. The contraceptive mechanism of the drug is suggested to be alkylation of the sperm membrane by free alpha-chlorohydrin in the epididymis.