Comparative Fertility of Diluted Bull Semen Treated with Calcium Chloride Complex Streptomycin or Dihydro Streptomycin Sulfate

In 1949 Easterbrooks et al. (1) reported that the addition of 100 units (Fg.) of streptomycin sulfate per milliliter of diluted bull semen increased fertility significantly on the basis of a split sample study when used in the routine operation of the Connecticut Artificial Breeding Association.Mixner (3), reporting simultaneously showed neither significant increase nor decrease when streptomycin calcium chloride complex and penicillin were both added at rates of 1,000 units per milliliter.One source of variation between these studies was that different compounds of streptomycin were used.The purpose of the present investigation was to test dihydro (DH) streptomycin sulfate and streptomycin calcium chloride complex (CCC), for evidence of ineompatibility with semen diluent buffers, as well as for their comparative effectiveness in increasing fertility rates. EXPERIMENTALThe problem was considered from two aspects.In the first phase of the study graduated concentrations of the two compounds varying from 100 to 1,000 units per milliliter in final dilution were added to phosphate and citrate buffers of various concentrations above, below and including those used routinely by artificial breeding organizations.After standing a few moments, a visible precipitate, calcium phosphate, 4 appeared in all tubes containing phosphate buffers to which streptomycin CCC had been added in excess of 100 units per milliliter.Because of the precipitation of these major components, the use of streptomycin CCC in phosphate containing diluents is considered contraindicated by the writers.No visible precipitation occurred at any level of either compound in any concentration of the citrate buffers.Laboratory tests with the two compounds in citrate buffers revealed no measarable variation in respect to bactericidal activity or effect upon sperm livability.The second phase of the work consisted of subjecting 14 ejaculates used by the Association over a period of 7 consecutive weekends in October and November, 1949, to .asplit sample study involving the two drugs at levels of 500 units per milliliter of diluted semen.This level was chosen in contrast to that previously