Bull sperm in Experiment 1 were added to a standard egg yolk-Tris extender containing 0, .25, .5, 1.0, 1.5, and 2.0% (vol/vol) of the detergent mixture, sodium and triethanolamine lauryl sulfate. Glycerol was added in one step to the initial extender or in three steps after cooling semen to 4 degrees C. The extended semen was packaged in .5-ml French straws and frozen over static nitrogen vapor. Thawing was at 4, 30, and 60 degrees C. There was little difference due to the method of adding glycerol provided detergent was present. Percentages of motile sperm after freezing in the six concentrations of detergent, in ascending order, were 31, 45, 52, 51, 48, and 36. Percentages of motile sperm following thawing at 4, 30, and 60 degrees C were 36.5, 46.0, and 48.6. Acrosome retention also was better preserved with the higher thaw temperatures. A second experiment, similar in design to the first one, was conducted with whole egg-Tris extender. The best results were in whole egg-Tris containing .125% detergent where post-thaw motile sperm of 70.4% greatly exceeded 30.7% without sodium and triethanolamine lauryl sulfate. Fertility of sperm frozen in yolk-Tris-detergent was equivalent to whole milk used as a control.

Two homologous radioimmunoassays for bovine follicle stimulating hormone (bFSH) were utilized in comparing the differential regulation of FSH and luteinizing hormone (LH) in response to ovariectomy or administration of gonadal steroids in cattle. There appeared to be significant LH cross-reactivity in one of the bFSH systems (bFSH-HS-2-17), but not in the other (bFSH-BP3). Concentrations of FSH in plasma measured by these two systems suggested both qualitative and quantitative differences. Following ovariectomy in heifers, LH concentrations in plasma were increased by 7.5 h, while FSH (measured in the bFSH-BP3 system) was not significantly elevated until 18 h. Administration of 200 micrograms of estradiol-17 beta to ovariectomized heifers inhibited levels of FSH in plasma but large doses of testosterone (100 mg), androstenedione (400 mg) and dihydrotestosterone (800 mg) had no effect. Similarly, LH was not affected by the androgens, while estradiol induced LH surges, leading to increased mean LH concentrations. In contrast to the results in heifers, LH concentrations in plasma from steers were inhibited by administration of androgens as well as by estradiol. In steers, FSH (bFSH-BP3) was marginally inhibited by estradiol and not at all by the androgens. Differences in the secretory patterns of FSH and LH also occurred in intact heifers during the estrous cycle. The 72-h period preceding estrus (follicular phase) was characterized by rapidly declining serum progesterone concentrations, followed by concurrent increases in both LH and estradiol. The circulating levels of bFSH (BP3) tended to decline during this interval. Overall, during the estrous cycle, progesterone levels were positively correlated with bFSH-BP3 (r = .37) and negatively correlated with LH (r = -.39). The gonadotropins were not significantly related (r = -.15). These relationships are consistent with the concept that LH controls the final stages of follicular development in cattle and that FSH may exert only a permissive effect.

No abstract

Because microfloral content of stallion semen tends to be high, and strains may be resistant to commonly used antibiotics, amikacin was tested with stallion semen and compared with bull semen. Nine ejaculates to stallion semen were incubated at 37 C in egg yolk-tris extender for 0, 2, 4, 6, 8 and 10 h in the presence of amikacin concentrations of 0, 50, 100, 250, 500, 1,000 and 10,000 microgram/ml, with penicillin and penicillin-streptomycin as controls. Averaged over all incubations, spermatozoal motility was 44, 48, 49, 46, 45, 45 and 19%, for increasing concentrations of amikacin, compared with 52 and 47% for penicillin and penicillin-streptomycin controls. The 10,000 microgram/ml concentration of amikacin was the only treatment that suppressed sperm motility (P less than .01). Amikacin (0, 50, 100, 250, 500, 1,000 2,500, 5,000 and 10,000 microgram/ml) and 1,000 IU of penicillin G plus 1,000 microgram of streptomycin/ml or 10,000 IU of penicillin G/ml were added to nine ejaculates of bull semen stored at 4 C in egg yolk-tris extender, and evaluated after 0, 1, 3, 5 and 7 d. The percentage of motile spermatozoa, with increasing levels of amikacin, was 66, 67, 66, 64, 67, 68, 74, 68 and 53%, respectively. Amikacin, at 2,500 microgram/ml, resulted in the highest (P less than .01) motility compared to the other levels of antibiotics after 7 d storage. Both 10,000 microgram of amikacin and 10,000 IU of penicillin G/ml depressed (P less than .01) the mean percentage of motile bull spermatozoa. These studies demonstrate that high concentrations of amikacin can be added to stallion and bull semen without depressing motility of spermatozoa.