Effects of a new antibiotic combination on post-thaw motion characteristics and memberane integrity of buffalo and Sahiwal bull spermatozoa and on the bacteriological quality of their semen

In this study the effects of a new antibiotic combination, i.e., gentamycin, tylosin and linco-spectin (STLS) on post-thaw motion characteristics, plasma membrane integrity, sperm morphology and the total aerobic bacterial. counts (TABC) in buffalo and Sahiwal bull semen were investigated. Ten ejaculates, five each from a buffalo and a Sahiwal bull, possessing more than 60% sperm motility were used. The ejaculates were diluted in Tris-citric acid (TCA) extender (at 37 degree centigrade; 50 X 106 spermatozoa/ml), containing either GTLS (gentamycin 500 mug/ml, tylosin 100 mug/ml and linco-spectin 300/600 mug/ml), streptomycin 1000 mug/ml and penicillin 1000 iu/ml (SP), or negative control with no antibiotics (NCON). Samples were cooled to 4 degree centigrade in 2 hours, equilibrated at 4 degree centigrade for 4 hours, filled in 0.5 ml straws, frozen in a controlled rate cell freezer and plunged into liquid nitrogen. Frozen semen was thawed at 37 degree centigrade for 15 seconds. Post- thaw sperm motion characteristics, plasma membrane integrity and sperm morphology were determined. To aerobic bacterial counts and the frequency of appearance of bacterial genera were determined in neat semen, after dilution, and after freezing and thawing. Mean motilities (visual, computer-assisted, linear a circular), velocities (straight-line, average path and curvilinear) and lateral head displacement (LHD) in post-thaw semen samples did not differ due to antibiotics or species. Same was true for sperm plasma membrane integrity. Morphologically abnormal spermatozoa were lower (P0.05) in GTLS and SP than in NCON. Sperm cells possessing normal acrosomes were higher (P0.01) in GTLS and SP than in NCON. Total aerobic bacterial counts in post-thaw samples were lower (P0.05) in GTLS than in SP or NCON. Staphylococcus and micrococcus were lower in samples treated with GTLS than that of SP or NCON Pseudomonas and E.coli were more frequent in buffaloes than Sahiwal bull samples. Proteus a corynebacteria were scarcely present. In conclusion, GTLS was not determintal to post-thaw motion characteristics, sperm morphology and membrane integrity of buffalo and Sahiwal bull spermatozoa. Furthermore, it efficiently reduced the number of aerobic micro- organisms in buffalo and Sahiwal bull semen.