Pharmakologisch unterstützte manuelle Spermagewinnung und computergestützte Spermienkopfmorphometrie beim Breitmaulnashorn (Ceratotherium simum)

Pharmacologically enhanced manual semen collection and computer assisted sperm head morphometry in the white rhinoceros (Ceratotherium simum) In this study the influence and applicability of pharmacologically enhanced semen collection in the white rhinoceros (Ceratotherium simum) was investigated. Obtained semen samples were assessed by routine methods. Additionally, computer assisted sperm head dimensions were determined for 15 individuals and a morphometric analysis was performed. A combination of the alpha-2-agonist Detomidine-Hydrochloride (Domosedan) and the partial opioid agonist Butorphanol (Butomidor) was administered intramuscular. In order to provide adequate safety margins for the operating persons, important requirements consist in a restraint chute and conditioning of the rhinoceros to tolerate manipulations. In a double blind trial, conducted on two bulls of various age and breeding status, a strong positive influence of the alpha-adrenergic medication was noted on both, performance and the outcome of the manual desemination trials. The medication facilitated manual stimulation of the genital region and semen collection in both males, but was time consuming as repeated collection trials had to be performed in order to obtain a single ejaculate. Pharmacologically enhanced desemination trials with an artificial vagina could not induce ejaculations efficiently. The frequency of semen collection and semen quality varied considerably between the applied desemination techniques, but also between the rhinoceros bulls. Ejaculates collected by the pharmacologically enhanced manual stimulation technique were incomplete, consisted of small volumes (0,5 to 9,0 ml, with one exception of 23 ml), but were highly concentrated in some cases (total number of sperms up to 6,6 x 10E9 per ejaculate) and of good quality. Semen samples collected with an artificial vagina however, were of low quality and were contaminated by debris. Amongst other factors, the extensive duration of the penile erection in rhinoceroses, appears to limit the suitability of the artificial vagina for semen collection. The determination of sperm head dimensions in the white rhinoceros was based on a computer assisted morphometric analysis of ejaculates from 15 individuals. The samples consisted of pharmacologically enhanced manually collected semen and electroejaculates. The Hamilton Thorne Morphology Analyser IVOS (integrated visual optical system; Hamilton Thorne Research, Beverly, USA) allowed the measurement of six metric sperm head parameters. The sperm head dimensions found for the white rhinoceros with a mean length of 5,4 ± 0,3 micrometers and width of 2,8 ± 0,2 micrometers (x ± SD; n=7733 analysed sperms) resemble those of the horse as determined by the same analysis system (e.g. UHLENBROCK 1999). A definition of morphometric criteria was required prior to the morphometric analysis. Limit values for five morphologic categories were calculated based on statistic parameters (5. and 95. percentiles, minimum and maximum). The analysis revealed a comparatively broad variation in the number of sperm head anomalies for the 15 rhinoceroses, ranging from 4 to 16%. As to date, investigations on the relationship between morphometry and fertility cannot be conducted in this species, these morphometric results should be interpreted species-specific and in conjunction with further semen parameters. In conclusion, pharmacologically enhanced manual stimulation with an alpha-adrenergic medication is a suitable alternative method for repeated semen collection in the white rhinoceros, although problems with this method as described are evident. While a considerable variation in volume and concentration of the samples was noted for individual rhinoceros bulls, the sperm morphology and morphometry generally appeared homogenous.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Ludwig-Maximilians-Universität

Year

2003

Author dc:creator

• Silinski, Sandra

Repository record source_url

https://edoc.ub.uni-muenchen.de/1287/

OAI identifier oai:identifier

oai:edoc.ub.uni-muenchen.de:1287