77 grados Kelvin

LA SELECCIÓN DE RAZAS ES EL PRIVILEGIO … LA CONSERVACIÓN ex situ ES LA REGALÍA.

POST-COITAL SPERM RECOVERY IN THE SUMATRAN RHINOCEROS (Dicerorhinus sumatrensis).

Traditional methods of semen collection often require anaesthesia and are of limited success (Platz et al., 1979; Schaffer et al., 1990). Therefore, semen collection from postcoital females may be the only effective and acceptable sperm recovery method for some male rhinoceroses. It should be possible to apply this post-coital collection method to all rhinoceros species, providing post-copulatory females can be managed appropriately. In addition to providing a source of spermatozoa for genome resource banking and future AI attempts, post-coital collection provides the opportunity to confirm that a male of unknown fertility is producing motile spermatozoa. The fertility of male rhinoceroses has been questioned because there are pairs of African white and black rhinoceroses breeding repeatedly without producing calves (Roth and Brown, 1999).
One advantage to collecting this type of sample is that it represents a sample of a natural ejaculate, whereas the small volumes of fluid emitted during manual stimulation or electroejaculation may not consist of the appropriate mixture of seminal fluids. The large volume (> 100 ml) of the samples collected in the present study compared with those reported for other methods (0.7–47 ml; Schaffer et al., 1990) support this suggestion. Since specific components of seminal fluid can affect sperm longevity and, ultimately, fertility (Mann and Lutwak-Mann, 1981; Baas et al., 1983), post-coital sperm recovery may provide samples better suited for assisted reproduction.
Despite the advantages of this alternative semen collection method, associated with it are novel features and challenges that require consideration. For example, the quality of postcoital samples may be lower than that of the initial ejaculate since many of the high quality sperm cells probably remain in the female reproductive tract to undergo transport to the oviducts. However, inseminated equine spermatozoa take up to 4 h to complete their transport to the oviducts (Troedsson et al., 1998), thus the quality of samples collected within 1 h of copulation may be representative of the quality of the initial ejaculate.
In this study, the male appeared to produce ejaculates containing high proportions of spermatozoa with abnormal heads. Although it is possible that the abundance of structurally abnormal spermatozoa in post-coital samples is slightly influenced by the selective properties of the female reproductive tract (Saacke et al., 1998), the high ratio of primary to secondary sperm abnormalities indicates that sample quality was poor at ejaculation.

Journal of Reproduction and Fertility (2000) 118, 263–271

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