Lipid profiles of canine spermatozoa as revealed via matrix-assisted laser desorption/ionization mass spectrometry.

In this study, we investigated the ability of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) to characterize the lipid contents of canine spermatozoa. For that, samples of pure semen were analysed. Indeed, quite comprehensive lipid coverage was observed, and the most abundant phospholipid ions detected were from four phosphatidylcholines, that is those of m/z 760.6; 782.6; 808.6; and 830.6 and one of m/z 725.6 from a sphingomyelin. In conclusion, MALDI-MS was found to offer an easy, fast, accurate, and sensitive analytical method for lipid profiling in canine spermatozoa and could be used as a tool to select sires by assessing the relationship between sperm lipid profiles and variables such as age and breeding history as well as to study the effects of cryopreservation on lipid contents.

Effects of immunization against luteinizing hormone-releasing hormone and treatment with trenbolone acetate on reproductive function of beef bulls and steers.

The objectives of this study were 1) to evaluate the ability of trenbolone acetate (TBA) administered in tandem with LHRH immunization to suppress reproductive function in bulls and 2) to examine the effects of LHRH and androgen (TBA) signaling on pituitary gland function. Forty-four Angus × Hereford crossbred calves (BW=225 ± 2 kg; age=187 ± 6 d) received castration, LHRH immunization, or TBA administration in a 2 × 2 × 2 factorial design. Treatment groups receiving LHRH immunization contained 6 animals, whereas other treatment groups contained 5 animals. Animals immunized against LHRH received a primary injection and 2 booster injections of ovalbumin-LHRH-7 fusion protein on d 0, 42, and 196, respectively. Animals treated with TBA were implanted on d 224. Serum LHRH antibodies increased (P<0.05) after each booster for immunized animals, but were negligible in nonimmunized animals throughout the experiment. Serum testosterone concentration (P<0.001) and scrotal circumference (P<0.05) were depressed in LHRH-immunized bulls compared with nonimmunized bulls by d 84 and 168 of the experiment, respectively. Treatment with TBA tended (P=0.08) to decrease serum testosterone concentrations of nonimmunized bulls. Weights of testes at slaughter were decreased (P<0.001) for LHRH-immunized (232 ± 41 g) compared with nonimmunized (752 ± 45 g) bulls, but did not differ (P=0.80) between TBA-implanted (500 ± 49 g) and nonimplanted bulls (484 ± 36 g). Both LHRH immunization and castration decreased pituitary gland stores of LH and FSH (P<0. 001). There was no effect (P>0.10) of TBA on pituitary gland FSH content and only a tendency (P=0.09) to increase pituitary gland LH content. Immunization against LHRH decreased expression of LH ß-subunit and common α-subunit genes (P<0.001). Castration increased expression of LH ß-subunit and common α-subunit genes (P=0.02). Treatment with TBA further suppressed (P=0.04) α-subunit mRNA expression in LHRH-immunized steers. In summary, LHRH immunization decreased synthesis and storage of LH and decreased storage, but not synthesis of FSH in bulls. The increased synthesis of LH and FSH in nonimmunized, but not LHRH-immunized steers suggests that castration removes the negative feedback on gonadotropin synthesis but that LHRH is still needed for release of these hormones. Androgen replacement with TBA did not restore the negative feedback control of gonadotropin synthesis.

Comparative analyses of semen and endocrine characteristics of free-living versus captive jaguars (Panthera onca).

Semen and blood samples were obtained from free-living (n = 6) and captive (n = 8) jaguars (Panthera onca) to compare reproductive characteristics between the two populations. Semen samples were analysed for volume (ml), percentage of motile spermatozoa, rate of forward progression (0-5), concentration (10(6) ml(-1)), total sperm count (10(6)) and sperm morphology. Serum testosterone concentration was determined by radioimmunoassay. Although ejaculate volume was greater in captive jaguars (n = 47 samples) than in free-living jaguars (n = 7 samples) (P < 0.05), the free-living jaguars produced more total spermatozoa (59.3 +/- 12.8 versus 152.0 +/- 88.0 x 10(6), respectively; not significant) with better viability and forward progression (2.8 +/- 0.1 versus 3.5 +/- 0.2, respectively; P < 0.05) and more spermatozoa with normal morphology (73.5 +/- 3.9 versus 5.0 +/- 1.1%, respectively; P < 0.05). Serum testosterone concentrations were similar for captive and free-living male jaguars (3.1 +/- 0.7 and 2.1 +/- 0.8 ng ml(-1), respectively). In summary, the data showed that semen may be collected successfully from free-living jaguars and evaluated under field conditions to establish normative reproductive values in this species. The results also indicate that jaguars maintained in zoos show inferior seminal characteristics compared with free-living animals.