Reproductive soundness of captive southern and northern white rhinoceroses (Ceratotherium simum simum, C.s. cottoni): evaluation of male genital tract morphology and semen quality before and after cryopreservation
Introduction
Substantial knowledge on the reproductive physiology of the female white rhinoceroses has been gathered over the last 10 years [1], [2]. The impetus for these studies was a low rate of reproduction in the captive population [3]. Acyclic and erratic luteal activity, mating, conception and pregnancy failures and reproductive ageing have been identified in female white rhinoceroses that have low rate of reproduction [1], [4], [5], [6]. These problems are currently being addressed [7]. However, little emphasis has been put on the evaluation of male fertility. Considering that 81% of all male white rhinoceroses in the Species Survival Programs have not yet sired offspring [8], male fertility may represent a contributing factor to the reproductive failure of the captive population. Besides the description of different semen collection methods and basic reproductive data for three rhinoceros species [9], [10], to date analysis of reproductive fitness in a significant number of non-reproducing males has not been performed. Clinical examination of reproductive organs and assessment of semen quality have historically been used to predict potential fertilizing capability of stallions [11], [12].
In this study, reproductive tract ultrasonography and electroejaculation were used in tandem to obtain information on the reproductive parameters of the male white rhinoceros. The purpose of this study was to compare the reproductive efficacy of mature, non-reproducing males managed in groups with different male to female ratios. The effects of changing the housing management of male and resulting upgrade in social status on reproductive factors were instigated in one case. For the prevention of extinction and the improvement of assisted-reproduction programs and sperm banks of endangered species [13], freshly collected semen via electroejaculation was used to design protocols for storage of cooled semen and cryopreservation. This is an essential prerequisite for artificial insemination in rhinoceros.
Section snippets
Histology
Prior to the main investigations of this study, the genital tracts of two male rhinoceroses (28/21 years) were examined post mortem to establish further baseline values to existing data [10], [14]. The genital tracts were exenterated, frozen at −20 °C during shipment and dissected after thawing. The morphologic and ultrasonographic characteristics of the genital tracts were ascertained in a water bath before the testis, and epididymis were fixed in 10% formalin. After fixation, tissue samples
Semen collection and assessment
A total of 34 ejaculates were collected from 21 male rhinoceroses. The mean ejaculate volume of a white rhinoceros was 80.2 ± 13.0 ml. Semen quality varied considerably between rhinoceroses. The morphologic integrity of spermatozoa also differed significantly between the progressive-motility categories (P < 0.01; Table 2). The percentage of motile spermatozoa showed a significant positive correlation to the percentage of morphologically intact spermatozoa (Spearman r = 0.576, P < 0. 001). The
Discussion
To date, the reproductive status of male white rhinoceroses has scarcely been evaluated. This is mainly due to anaesthesia risks [16] and to the technical difficulties involved with fertility assessment of male white rhinoceros. The provided information about the reproductive status of 21 captive white rhinoceroses represents a substantial physiologic database on reproductive parameters in this species. The correlations discovered between the volume of the male accessory sex glands and the
Acknowledgements
The International Rhino Foundation and SOS Rhino, USA funded this work. The authors are grateful for additional financial support by the African Lion Safari ltd., Cambridge, Canada; Burgers’ Zoo, Arnhem, Netherlands; La Palmyre Zoo, France; Schwerin Zoo, Germany. Gratitude is extended especially to Igal Horowitz and Amelia Terkel form the Zoological Center Tel Aviv/Ramat Gan for their work and support, contributing a substantial number of animals to this study. The authors thank the staff of
References (51)
- et al.
Ultrasonography as an important tool for the development and application of reproductive technologies in non-domestic species
Theriogenology
(2000) Reproductive considerations: mare and stallion
Vet. Clin. North Am. Equine Pract.
(2002)- et al.
Ultrasonographic characterization of ovarian events and fetal gestational parameters in two southern black rhinoceros (Diceros bicornins minor) and correlation to fecal progesterone
Theriogenology
(2001) - et al.
Freezing epididymal sperm from white rhinoceroses (Cerathoterium simum) treated with different cryodiluents
Theriogenology
(1999) - et al.
Objective analysis of stallion sperm motility
Theriogenology
(1988) Reproductive behavior of stallions and mares: comparison of free-running and domestic in-hand breeding
Anim. Reprod. Sci.
(2000)- et al.
Relationship between androgens, environmental factors and reproductive behavior in male white rhinoceros (Cerathoterium simum simum)
Hormones Behav.
(2004) The causes of reduced fertility with cryopreserved semen
Anim. Reprod. Sci.
(2000)- et al.
Reproductive cycle length and pregnancy in the southern white rhinoceroses (Ceratotherium simum simum) as determined by fecal pregnane analysis and observations of mating behavior
Zoo Biol.
(1999) - et al.
Problems associated with the low reproductive rate in captive white rhinoceroseses (Cerathoterium simum)–an update
Verhandlungsbericht über die Erkrankungen der Zoo-und Wildtiere
(2003)
Faecal progesterone metabolite analylsis for non-invasive monitoring of reproductive function in the white rhinoceroses (Ceratotherium simum)
Animal Reprod. Sci.
Can the problems associated with the low reproductive rate in captive white rhinoceroses (Cerathoterium simum) be solved within the next 5 years?
Verhandlungsbericht über die Erkrankungen der Zoo- und Wildtiere
Methods of semen collection in an ambulatory greater one-horned rhinoceroses (Rhinceros unicornis)
Zoo Biol.
Ultrasonographic monitoring of artificially stimulated ejaculation in three rhinoceroses species
J. Zoo Wildlife Med.
Can the fertility potential of a seminal sample be predicted accurately?
J. Androl.
Evaluation of the stallion for breeding
Acta Vet. Scand.
Preservation of endangered species and populations: a role for genome banking, somatic cell cloning and androgenesis?
Mol. Reprod. Develop.
Clinical implications of rhinoceros reproductive tract anatomy and histology
J. Zoo Wildlife Med.
Genetic Kinship and social structure in a herd of square-lipped rhinoceroseses (Cerathoterium simum simum) at the Zoological Center, Tel Aviv/Ramat Gan. Israel
Zoo Biol.
Seasonal timing of sperm production in roe deer: interrelationship among changes in ejaculate parameters, morphology and function of testis and accessory glands
Theriogenology
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