Whole milk extender with antibiotics to eliminate Campylobacter fetus from frozen bovine semen

Failure of antibiotics gentamycin, tylosin, lincomycin and spectinomycin to eliminate Mycoplasma bovis in artificially infected frozen bovine semen

To study the effect of antibiotics upon Mycoplasma bovis in fresh bovine semen just before freezing, specimens of bovine semen were artificially infected with 1 of 9 different strains of M. bovis. Inocula of each strain were prepared to contain 10(5) to 10(6)/mL colony-forming units of M. bovis at 3 different stages of the growth phase. The infected semen was diluted with a Tris extender by a 3-step procedure using an antibiotic mixture of gentamicin, tylosin, lincomycin and spectinomycin (GTLS). This semen-antibiotic mixture was placed into French straws that were stored at -196 degrees C. The control semen specimens contained no antibiotics Mycoplasmas were counted after 8 d of storage in 3 decimal dilutions of the frozen semen. No evident effect was noticed upon the 9 tested strains of mycoplasmas in the semen frozen with the antibiotics, compared with that of the untreated control samples. It was further shown that this lack of effect was irrespective of the stage of the growth phase of the mycoplasmas. It was concluded that the antibiotic mixture (GTLS) in semen specimens is not capable of total elimination of mycoplasmas in frozen bovine semen.

Control of Campylobacter fetus in artificially contaminated bovine semen by incubation with antibiotics before freezing

Fresh, diluted semen containing 1.55 X 10(6) cfu/ml of Campylobacter fetus subsp. venerealis was incubated with 500 iu of penicillin, 500 micrograms of streptomycin, 160 micrograms of lincomycin and 300 micrograms of spectinomycin per ml at 35 degrees C for 0, 1, 2, 5, 10, 20 or 40 minutes. The semen was cooled to 5 degrees C, packaged in 0.25 ml French straws and then frozen in liquid nitrogen for 2 weeks. Immediately after thawing and removal of the antibiotics by centrifugation semen samples from each of the seven treatment groups were cultured as for C. fetus. Semen samples were also examined by in-vitro tests for sperm motility prior to and post-freezing. Incubation with the antibiotics for 5, 10, 20 or 40 min prior to freezing reduced the numbers of C. fetus in the semen to non-detectable levels in 38%, 69%, 88% and 100% of samples respectively. The incubated semen showed no significant reduction of sperm motility although fertility trials have not been done.

Antibiotics for bull semen frozen in milk and egg yolk extenders

In six experiments, gentamicin, clindamycin, amikacin, minocin, tylosin, and Linco-Spectin were tested for their effect on motility and fertility of frozen bull spermatozoa and all but clindamycin were used in fertility trials. Antibiotics were added to raw (unextended) semen and nonglycerol portions of the three commonly used semen extenders, whole milk, egg yolk-Tris, and egg yolk-citrate. Semen was frozen in .5-ml straws, stored in liquid nitrogen, and thawed at 37 degrees C for 30 s. Postthaw percentage of motile spermatozoa in antibiotic-treated semen was different for individual bulls in each experiment. Percentage of motile sperm was slightly but significantly depressed at the higher concentrations of clindamycin and Linco-Spectin tested in whole milk and with minocin in the two egg yolk extenders. In general, nonspermicidal concentrations of each antibiotic were established. Of five antibiotics tested for fertility, only gentamicin reduced fertility on the basis of 59-d nonreturn rates.