Reproductive physiology and artificial insemination studies in wild and captive gerenuk (Litocranius walleri walleri)

EVALUATION OF A VISUAL ENZYME-LINKED IMMUNOSORBENT ASSAY (ELISA) FOR PREGNANCY DETECTION IN FOUR UNGULATE SPECIES

This study evaluated the use of a commercially available, visual enzyme-linked immunosorbent assay (ELISA) for diagnosis of pregnancy in okapi (Okapia johnstoni), gerenuk (Litocranius walleri), eastern giant eland (Tragelaphus derbianus spp. gigas), and dama gazelle (Nanger dama). This assay has been validated for use in domestic cattle, sheep, goats, and water buffalo. Unlike other blood-based pregnancy associated glycoprotein (PAG) detection methods, this assay does not require sophisticated laboratory equipment for detection or interpretation and can therefore be utilized in many settings. Banked serum samples from gerenuk (n = 11), giant eland (n = 4), dama gazelle (n = 33) and okapi (n = 3) were tested, and a pregnant and nonpregnant sample from each individual were included. The ELISA showed 100% sensitivity and specificity in gerenuk and giant eland samples, and 0% sensitivity in dama gazelle and okapi samples. Using this assay, pregnancy was detected by 7-8 wk gestation in gerenuk and 6 wk in giant eland. These results are consistent with previous studies that were able to accurately detect pregnancy in other members of the family Bovidae, but it is possible that PAGs present in okapi and dama gazelle are structurally dissimilar relative to the intended test target, and are therefore unrecognizable using this test. The faint positivity in the dama gazelle assays may be due to cross-reactivity with other proteins in the sample, or due to inconsistent binding with the dama gazelle PAG. This ELISA appears to be an accurate, rapid, and inexpensive method of point-of-care pregnancy diagnosis in gerenuk and giant eland, but not okapi and dama gazelle. Additional studies should be pursued to further characterize the limits of pregnancy detection using this assay in gerenuk and giant eland, and to investigate the validity of this test in other nondomestic ruminant species.

Effect of Season and Social Environment on Semen Quality and Endocrine Profiles of Three Endangered Ungulates (Gazella cuvieri, G. dorcas and Nanger dama)

Knowledge of factors affecting semen quality could be of great importance for the collection and preservation of semen from threatened animals. To assess the effect of seasonality, sperm parameters and testosterone levels were examined throughout the year and compared with the distribution of conceptions. Cuvier's gazelle showed higher sperm quantity in April, coinciding with one peak of conceptions. In dorcas gazelle, sperm parameters showed a drop in October. However, percentage of conceptions increased during that month. In Mohor gazelle, sperm quality was best in April and August, in agreement with higher conception rates and high testosterone levels. Percentage of conceptions was correlated with photoperiod and rainfall in Cuvier's gazelle and with temperature in Mohor gazelle. To assess the effect of social environment, semen quality, testosterone and cortisol levels were quantified in males housed alone, in bachelor groups or with females. No differences were seen in Cuvier's and Mohor gazelles' semen traits, whereas dorcas males housed with females showed lower semen quality than males kept alone or with other males. Overall, ejaculate quality is influenced by seasonal factors in the three gazelle species, while social factors only appear to affect that of dorcas gazelle.

Strong Heterogeneity in Advances in Cryopreservation Techniques in the Mammalian Orders

Between 1970 and 2012, vertebrate abundance has declined by 58% with an average annual decline of 2%, calling for serious action to prevent a mass extinction and an irreversible loss of biodiversity. Cryobanks and cryopreservation have the potential to assist and improve ex situ and in situ conservation strategies by storing valuable genetic material. A great deal of studies concerning cryopreservation have been performed within the class Mammalia, although no systematic overview has previously been presented. The objective of this study is therefore to evaluate the status, pattern and future of cryopreservation within Mammalia. A strong disproportional distribution of studies in examined orders is displayed. For the majority of examined orders less than 10% of species has been examined. However, the cryopreservation of germplasm has in several cases been successful and resulted in successful applications of assisted reproductive techniques (ARTs). Various obstacles are associated with the development of cryopreservation protocols, and among them the most prominent is interspecific differences in cryotolerance. Extrapolation of protocols in closely related species is considered the most applicable procedure, and a future supplement to overcome this problem is the examination and comparison of cryobiological traits. Successful protocols have been developed for the vast majority of domesticated mammals, which gives incentive for the further extrapolation of protocols in threatened species.

Non-invasive hormonal characterization of the ovarian cycle, pregnancy, and seasonal anestrus of the female addra gazelle (Nanger dama ruficollis)

Non-invasive fecal hormone metabolite monitoring was used to characterize the estrous cycle, pregnancy, and seasonal anestrus of the critically endangered addra gazelle (Nanger dama ruficollis). With less than 250 animals remaining in the wild and ∼168 individuals managed in captivity, it is crucial to maintain sustainable populations. Progestogen and estrogen profiles were obtained from analysis of fecal samples collected approximately every other day, within varying intervals, over the course of 7 years (n = 8 adult females). Average estrous cycle length was 19.5 ± 0.4 days (range, 14-26 days), with a luteal phase length of 14.6 ± 1.2 days (range, 10-16 days), and an inter-luteal period of 5.2 ± 1.4 days (range, 2-7 days). Mean gestation length for six pregnancies was 200.7 ± 0.4 days (range, 200-202 days). Fecal progestogens increased at 12 weeks of gestation and remained elevated until parturition. Addra gazelle females exhibited a period of seasonal anestrus with consistently low progestogen concentrations and no cyclic activity from about September to March. Analysis of reproductive and climate records demonstrated a peak in U.S. births that coincided with maximal rainfall in the native habitat of the addra gazelle. Results show that estrous cycle, luteal phase, and inter-luteal phase lengths in addra are similar to those observed in other gazelle species, however, to our knowledge, this is the first study to demonstrate seasonal anestrus in the Nanger genus.

Biobanking efforts and new advances in male fertility preservation for rare and endangered species

Understanding and sustaining biodiversity is a multi-disciplinary science that benefits highly from the creation of organized and accessible collections of biomaterials (Genome Resource Banks). Large cryo-collections are invaluable tools for understanding, cataloging, and protecting the genetic diversity of the world's unique animals and plants. Specifically, the systematic collection and preservation of semen from rare species has been developed significantly in recent decades with some biobanks now being actively used for endangered species management and propagation (including the introduction of species such as the black-footed ferret and the giant panda). Innovations emerging from the growing field of male fertility preservation for humans, livestock species, and laboratory animals are also becoming relevant to the protection and the propagation of valuable domestic and wild species. These new approaches extend beyond the “classical” methods associated with sperm freezing to include testicular tissue preservation combined with xenografting or in vitro culture, all of which have potential for rescuing vast amounts of unused germplasm. There also are other options under development that are predicted to have a high impact within the next decade (stem cell technologies, bio-stabilization of sperm cells at ambient temperatures, and the use of genomics tools). However, biobanking efforts and new fertility preservation strategies have to expand the way beyond mammalian species, which will offer knowledge and tools to better manage species that serve as valuable biomedical models or require assistance to reverse endangerment.

Implementing the use of a biobank in the endangered black-footed ferret (Mustela nigripes)

In the current global health climate, many conservation biologists are managing crisis situations, including increased species extinction rates. One strategy for securing wildlife populations into the future is to preserve biomaterials in genome resource banks (GRB; or 'biobanks'). However, for GRBs to be successful we must understand the fundamental reproductive biology of species, along with developing assisted reproductive techniques (ARTs), including AI and semen cryopreservation. ART has been successfully used for several taxa, from amphibians to mammals, including ungulates, carnivores and primates. Not all these success stories implemented the use of a biobank, but one example that discussed herein is the black-footed ferret (Mustela nigripes) GRB. From a founder population of seven individuals, this species has been breeding in a managed setting for nearly 30 years. The goal of the breeding program is to maintain genetic integrity by ensuring each individual has the opportunity to pass his/her genes onto the next generation, while simultaneously providing animals for release into the wild. Scientists have used ART (e.g. AI) in the recovery program. Recently, semen from an individual of the founder population that was cryopreserved for up to 20 years was used successfully for AI, which improved the genetic diversity of the population. The black-footed ferret recovery program can serve as a model for other endangered species and demonstrates the usefulness of ART and GRBs to maintain highly endangered species into the future.

Implications of the Nagoya Protocol for genome resource banks composed of biomaterials from rare and endangered species

The Nagoya Protocol on Access to Genetic Resources and the Fair and Equitable Sharing of Benefits Arising from their Utilisation is a multilateral legal instrument within the Convention on Biodiversity. It has now come into force, having been signed by 92 countries, 68 of which have ratified it, but notably these do not yet include the US, China, Canada and Russia. The overarching objective of the Nagoya Protocol is to prevent the unfair commercial exploitation of a country's biodiversity and it also protects traditional knowledge. Although the intentions seem reasonable and equitable, the provisions of the Nagoya Protocol will have major effects on the ability of researchers in both the commercial and non-commercial sectors to access genetic materials (which are widely defined and include almost every conceivable animal product, as well as whole animals) from around the world. It also places a heavy bureaucratic burden on researchers and their institutions, which must comply with an international standard and obtain an International Certificate of Compliance proving that all samples will be collected according to the terms of the Protocol. Herein we review of the unforeseen implications of the Nagoya Protocol in relation to biobanking and animal conservation.

Saving wild ungulate diversity through enhanced management and sperm cryopreservation

Wild ungulates throughout the world face the impending risk of extinction. Small founding population size, lack of interest in exhibiting wild ungulates and declining space in zoos are not sustaining ex situ populations. Animals managed in ex situ collections continue to experience >20% neonate loss globally. To ensure population sustainability there is a critical need to: (1) manage ungulates in large herds, increasing mate choice and reproductive efficiency; (2) improve husbandry and genetic management; and (3) develop consistent assisted reproductive technologies, including sperm cryopreservation and AI. Recently, new models in the management of ungulates have begun to emerge. Animal managers and researchers are also beginning to exploit advances in genomics to improve genetic management of their collections. Furthermore, the past decade has witnessed significant advances particularly in semen collection and cryopreservation in numerous species. Advances in gonadal tissue cryopreservation now offer additional opportunities to preserve male genomes. The new knowledge generated is enabling the creation of genetic (sperm) banks to rescue and enhance reproductive management of wild ungulates. The present paper reviews the threats to ungulate populations, the status and relevance of animal management and biomaterial banking efforts to ensure long-term survival of these charismatic species.

Recent advances and prospects in germplasm preservation of rare and endangered species

Fertility preservation strategies using cryopreservation have enormous potential for helping sustain and protect rare and endangered species, especially to assist managing or 'rescuing' the genomes of genetically valuable individuals. However, wide-scale applications are still limited by significant physiological variations among species and a sheer lack of fundamental knowledge about basic reproductive traits as well as in germplasm cryobiology. Cryo-studies have been conducted in more species (mainly vertebrates) in the recent years but a vast majority still remains un-studied. Semen cryopreservation represents the most extensive effort with live births reported in more and more species after artificial insemination. Oocyte freezing remains challenging and unsuccessful in wild species and will require more research before becoming a standard procedure. As an alternative to fully grown gametes, gonadal tissue preservation has become a promising option in vertebrates. Yet, more fertility preservation options are necessary to save species so a change in strategy might be required. It is worthwhile thinking beyond systematic characterizations and considering the application of cutting edge approaches to universally preserve the fertility of a vast array of species.

Fecal steroid analysis for evaluating ovarian function in the greater kudu (Tragelaphus strepsiceros) and lesser kudu (Tragelaphus imberbis)

Seasonal reproductive-endocrine norms have not been described for the genus Tragelaphus, which consists of seven species of African antelope. Longitudinal patterns of progesterone metabolite excretion were assessed by radioimmunoassays in fecal samples collected noninvasively (three to seven samples per week) from greater kudu (Tragelaphus strepsiceros, n = 4) and lesser kudu (Tragelaphus imberbis, n = 4). Progesterone metabolite excretion patterns revealed seasonal estrous cycles in both species, and discrimination of pregnant versus nonpregnant females was achieved in lesser kudu. These data reveal the value of fecal progesterone metabolites for establishing reproductive-endocrine norms in both zoo-maintained and free-living antelopes of the genus Tragelaphus.

Endocrine patterns of the estrous cycle and pregnancy of wildebeest in the Serengeti ecosystem

Despite the importance of the western white-bearded wildebeest (Connochaetes taurinus mearnsi) to the Serengeti-Mara ecosystem, surprisingly little is known about the reproductive physiology of this keystone species. A longitudinal, non-invasive endocrine study was conducted on female wildebeest captured from the Serengeti-Mara migration and maintained for approximately 16 months in large fenced enclosures within the species' natural range. An intact bull was introduced to a female subgroup (n=5), while remaining females (n=10) were unexposed to a male. Fecal progestagen patterns reflected ovarian activity and pregnancy. In non-pregnant animals, luteal and inter-luteal baseline progestagen values differed (p<0.001) over time, thereby allowing identification of recurrent estrous cycles. The average durations of the luteal phase, estrous cycle, gestation, and post-partum anestrus were 14.3+/-0.5, 22.6+/-1.0, 240.8+/-11.7, and 104.1+/-15.6 d, respectively. Annual reproductive patterns indicated a distinctive period of ovarian activity that extended from 13 May through 3 December (203.5+/-29.9 d) with all unmated females displaying from one to 14 estrous cycles. Progestagens were higher (p <0.001) in pregnant (n=4) than non-pregnant (n=10) cows. These data (1) reveal the value of fecal hormone monitoring for establishing the first ever endocrine profiles of female wildebeest in semi-free-living conditions in their native range, and (2) indicate that the species is a seasonal breeder that is polyestrous and a spontaneous ovulator.

Ejaculate characteristics, short-term semen storage and successful artificial insemination following synchronisation of oestrus in the Indian blackbuck antelope (Antilope cervicapra)

The blackbuck (Antilope cervicapra) is a small (20–30 kg) Indian antelope that is listed on Schedule I of the Indian Wildlife Protection Act, 1972. Studies were undertaken to develop assisted reproductive technologies, such as synchronisation of oestrus and non-surgical AI, to support the conservation and genetic management of this Indian antelope. Semen characteristics, testosterone levels and the feasibility of short-term cold storage of semen were investigated. Furthermore, different oestrous synchronisation protocols (norgestomet implants and prostaglandin injections) were evaluated for successful AI, defined as the birth of live young. Norgestomet ear implants and i.m. administration of pregnant mare’s serum gonadotropin (PMSG) resulted in successful pregnancies in two of five inseminated females, but both had twin pregnancies that were delivered prematurely. In contrast, two injections of prostaglandin 11 days apart were effective in synchronising oestrus in the blackbuck. Transcervical AI in oestrous-synchronised animals 72 and 96 h after the second prostaglandin injection resulted in successful pregnancies in four of six inseminated females (67%) and resulted in the delivery of three live fawns. These studies demonstrate the potential application of AI technology for the conservation of endangered ungulates. To our knowledge, this is the first report regarding the synchronisation of oestrus and successful non-surgical AI in blackbuck.

Idiopathic infertility in two captive male gerenuk (Litocranius walleri walleri)

Two adult male gerenuk (Litocranius walleri walleri) were confirmed infertile with distinctly varying clinical presentations. One animal had unilateral testicular degeneration/hypoplasia, and within 8 mo experienced atrophy/degeneration of the remaining testicle. The second animal had been previously treated with melengesterol acetate (MGA) milled in feed for 1 yr during puberty as part of an aggression-control study. The testes in this individual appeared normal both visually and on palpation; however, repeated semen collection consistently produced ejaculates containing high numbers of immotile spermatozoa, all of a single abnormal morphology: shortened tails, with normal total sperm counts for this species. Both gerenuk had cortisol concentrations within normal ranges for adult male gerenuk. Analysis of serum mineral concentration revealed zinc levels that would be considered low in domestic cattle. Testosterone levels were low for the animal discussed in case 1, but were within normal range for the animal in case 2 compared with other gerenuk. Investigations into endocrine causes, such as abnormal thyroid hormone concentrations and adrenal function, were unrewarding. Both animals discussed in this report are maternally related; therefore, a genetic cause of infertility cannot be ruled out. Further investigation into MGA, as well as the dietary zinc requirements for gerenuk, and resulting effects on spermatogenesis and testicular development are warranted.

A review on reproductive biotechnologies for conservation of endangered mammalian species

This review describes the use of modern reproductive biotechnologies or assisted reproductive techniques (ART) including artificial insemination, embryo transfer/sexing, in vitro fertilization, gamete/embryo micromanipulation, semen sexing, genome resource banking, and somatic cell nuclear transfer (cloning) in conservation programs for endangered mammalian species. Such biotechnologies allow more offspring to be obtained from selected parents to ensure genetic diversity and may reduce the interval between generations. However, the application of reproductive biotechnologies for endangered free-living mammals is rarer than for endangered domestic breeds. Progress in ART for non-domestic species will continue at a slow pace due to limited resources, but also because the management and conservation of endangered species is biologically quite complex. In practice, current reproductive biotechnologies are species-specific or inefficient for many endangered animals because of insufficient knowledge on basic reproduction like estrous cycle, seasonality, structural anatomy, gamete physiology and site for semen deposition or embryo transfer of non-domestic species.

Seasonal variations in semen characteristics, semen cryopreservation, estrus synchronization, and successful artificial insemination in the spotted deer (Axis axis)

Ten adult male spotted deer were monitored over a 2-year interval to determine seasonal variations in testicular size, semen characteristics and serum testosterone concentrations, and to determine if there was an association between season and type of antler. Mean (+/-S.E.M.) testicular volume (118.8+/-4.6 cm(3)), serum testosterone concentration (1.2+/-0.1 ng/mL), semen volume (4.1+/-0.6 mL), sperm concentration (338.3+/-24.9 x 10(6) mL(-1)), percentage of morphologically normal sperm (79.1+/-2.8%), and percentage of motile sperm (66.5+/-1.5%) were higher (P<0.05) in hard antler deer (peaked from March to May) than in deer with velvet antlers or in deer in which the antler has been shed. Thus, March-May was considered the physiologic breeding season for these deer; at this time, all stags had hard antlers. Furthermore, a Tris-citrate-based semen extender containing 4% glycerol and 20% egg-yolk was adequate for cryopreservation of semen. Estrus was induced with an implant containing norgestomet, timed transcervical AI was done with fresh semen, and 3 of 10 females were pregnant at 60 days, with fawns born 120 (premature), 240 and 243 days after AI. These results were considered a model for the use of assisted reproductive techniques to conserve other critically endangered deer species of India.

Inbreeding and Reproduction in Endangered Ungulates: Preservation of Genetic Variation through the Organization of Genetic Resource Banks

There is a constant increase in the number of species suffering marked reductions in population size. This reduction in size and the lack of genetic flow may lead to a decrease in genetic variability and to matings between close relatives (i.e. inbreeding) with an ensuing reduction in fitness. It is thus important to understand the mechanism underlying the deleterious effects of inbreeding and to develop reproductive biotechnologies that will allow the reduction of inbreeding depression by facilitating gene exchange between populations. The study of three endangered species of gazelles, Cuvier's gazelle (Gazella cuvieri), Mohor gazelle (Gazella dama mhorr) and dorcas gazelle (Gazella dorcas neglecta) has revealed that inbreeding negatively affects several semen parameters (motility, sperm morphology, acrosome integrity). Semen cryopreservation has been achieved in the three species but success varies depending on the diluent employed and the level of inbreeding. Artificial insemination of Mohor gazelles have led to the birth of the first gazelle born using frozen-thawed semen but improvements are needed before this technology can be applied on a routine basis for the genetic management of the populations. Collection of oocytes after ovarian stimulation, followed by in vitro maturation, fertilization and culture has met with some initial success in the Mohor gazelle. These, together with other reproductive technologies, will offer an invaluable help in preserving the maximum of genetic diversity of these and related endangered ungulate species.