Comparisons of antibiotic combinations to control Pseudomonas aeruginosa in bovine semen.

Raw semen experimentally contaminated with 10(6) Pseudomonas aeruginosa cells per milliliter was processed for use in artificial insemination (AI) using three different antibiotic combinations: a) gentamicin, lincomycin, spectinomycin and tylosin (GLST) directly added to contaminated raw semen followed by dilution with whole milk or egg yolk Tris containing GLST; b) penicillin, streptomycin, lincomycin, spectinomycin and minocycline (PSLSM) in whole milk used to dilute the contaminated raw semen followed by further dilution with glycerolated milk containing PSLSM; and c) penicillin, streptomycin, lincomycin and spectinomycin (PSLS) used with egg yolk Tris diluent in the same way as PSLSM and milk. Diluted semen was incubated at 35 degrees C for 5 or 40 min before cooling commenced. To assess the efficacy of the antibiotics in controlling P. aeruginosa, diluted semen samples were cultured for the organism before and after freezing. The GLST antibiotics added to raw semen and milk reduced the counts of P. aeruginosa before or after freezing. When egg yolk Tris was used, GLST inhibited the organism as indicated by its low growth in culture before freezing and absence of growth from samples after freezing. With PSLSM and PSLS treatments, the organism was recovered in milk and egg yolk Tris processed semen both before and after freezing. However, incubation at 35 degrees C for 40 min prior to cooling, compared to incubation of 5 min, appeared to reduce the bacterial counts after freezing.     

The value of sexed bovine semen

Semen sexing may be used in a variety of practical situations, where part (or all) of the herd may be inseminated with X‐ and Y‐chromosome‐enriched semen. Expressions are presented to calculate the net present value of progeny derived from a semen dose, dependent on the values of females and males, and on the efficiency of sexing. Sexed semen allows selling a higher proportion of the more valuable sex and also increases the value of animals retained for breeding through more intense selection. The expressions to economically evaluate sexed semen are quite general but numerical examples are presented for several practical situations of interest in Brazil.     

The concentration of estradiol-17 beta in bovine semen

This study was conducted to evaluate the influence of age, breed, epididymectomy and semen processing on the concentration of estradiol-17 beta (E2) in bovine semen. Semen was collected either by electroejaculation or with an artificial vagina. Neat semen samples were stored at -20 C until analysis. Processed, frozen semen and an egg yolk-citrate semen extender were obtained from a commercial semen processing firm and stored in liquid nitrogen at -196 C. The concentration of E2 in semen was determined by radioimmunoassay. Semen from mature (greater than 24 mo), fertile Brahman (n = 19), Brangus (n = 16), Charolais (n = 29), Holstein (n = 15) and Santa Gertrudis (n = 25) bulls was analyzed for E2 concentration, and no difference (P greater than .10) between breeds was found. There was no difference (P greater than .10) in seminal E2 concentration between mature, fertile bulls (n = 104) and epididymectomized bulls (n = 22). In semen collected from prepuberal (12 to 16 mo, n = 21), peripuberal (17 to 20 mo, n = 17) and mature (greater than 24 mo, n = 19), Brahman bulls, the mature bulls had a lower (P less than .01) semen E2 concentration than peripuberal and prepuberal bulls. There were no differences (P greater than .10) in seminal E2 concentration among peripuberal Angus (n = 8), Hereford (n = 8) and Brahman (n = 17) bulls.(ABSTRACT TRUNCATED AT 250 WORDS)     

The origin and species of yeasts in commercial preparations of bovine semen.

Whereas yeasts were not normally isolated from raw semen samples 13% of commercial frozen semen samples and 71% of preputial washings contained yeasts. Nine genera and 25 species of yeasts have been identified from these two sources. Yeasts originating in the preputial cavity were generally saprobic members of the genera Candida, Cryptococcus, Rhodotorula, Saccharomyces, Torulopsis and Trichosporon. Those originating as contaminants during processing were more likely to be opportunistic pathogens of the genus Candida. Conception was not necessarily affected by the presence of large numbers of Candida krusei or C. macedoniensis in the uterus.     

Survival of infectious bovine rhinotracheitis virus in stored bovine semen

No loss in the titre of infectious bovine rhinotracheitis virus was found during storage in semen at –196°C for 1 year.     

Absence of bovine leukosis virus in semen of seropositive bulls.

A polymerase chain reaction (PCR)-based detection system was established to identify the presence of bovine leukosis virus (BLV) DNA in bovine semen. Seventy-nine bulls were included in the study. Serum, peripheral blood leukocytes, and semen were collected from each of the 79 bulls. The BLV-specific antibody was detected in serum by agar gel immunodiffusion and viral DNA in blood and semen by PCR. Serologically, 29 of the 79 bulls were BLV positive. Twenty-seven of the 29 seropositive bulls and 1 of the seronegative bulls had BLV DNA in peripheral blood leukocytes. All 79 bulls tested PCR negative for the presence of BLV in semen. This data is strong evidence that properly collected semen from BLV seropositive bulls will not contribute to dissemination of this viral infection.     

Factors associated with the determination of antibiotic activity in bovine semen.

Rosaramicin, an agent shown to be effective in vitro against ureaplasma of bovine origin was tested as an additive to bovine semen extender. Although some reduction in semen quality occurred it was still deemed satisfactory for use. In a test involving 41 cows inseminated once at estrus with rosaramicin-treated semen (162 mcg/mL) the nonreturn rate was 24% compared to a calculated average for this semen of 63% (n = 3310). The effect of centrifugation, time and temperature was examined in vitro using a combination of 150 mcg of lincomycin, 300 mcg of spectinomycin and 450 mcg of tylosin against ten strains of bovine ureaplasma. This combination has ureaplasmacidal activity and is suggested as an additive to semen extenders for the control of ureaplasma.     

Inactivation of bovine herpesvirus 1 in semen using a hyperimmune egg yolk semen extender

Hyperimmune egg yolk semen extender was used for the inactivation of bovine herpesvirus (BHV-1) in experimentally infected bovine semen. As much as 5 x 10(4) TCID50/ml of virus was inactivated in semen as assayed by tissue culture. Moreover the hyperimmune egg yolk semen extender did not produce any adverse effect on the quality of the semen after being frozen/thawed in comparison with normal egg yolk semen extender (P > 0.05). The hyperimmune egg yolk semen extender is considered an important tool for containing the spread of BHV-1 from infected semen.