Successful in vitro production of embryos in the red deer (Cervus elaphus) and the sika deer (Cervus nippon)

A comparison of the biological properties of European red deer (Cervus elaphus elaphus) spermatozoa stored in the epididymides and in a liquid state at 5 °C

The biological properties of European red deer (Cervus elaphus elaphus) spermatozoa stored in the epididymides and in a liquid state were compared. Spermatozoa were collected from the epididymides harvested post-mortem. In the first variant, spermatozoa were diluted in two extenders (Bovidyl® and Salomon's), and were stored at 5 °C for up to 144 h. In the second variant, spermatozoa were stored in the epididymides at 5 °C for up to 144 h, and then diluted in the same extenders. Biological properties were evaluated after 0, 48, 96, and 144 h of storage. Sperm motility parameters were determined in the CASA system. Plasma and acrosomal membrane integrity, mitochondrial activity, apoptotic changes, and DNA integrity were assessed by the fluorescence method. Most variables were significantly influenced by the storage method and time. At 144 h, differences (P ≤ 0.05) in sperm parameters were observed between storage variants. Total motility (TMOT), plasma membrane integrity, and mitochondrial activity decreased below 50% of baseline values in the spermatozoa stored in the epididymides, but remained above 70% of baseline values in the spermatozoa stored in a liquid state. The compared storage variants did not differ in TMOT, mitochondrial activity, or the percentage of viable spermatozoa without apoptotic-like changes up to 96 h of storage, regardless of the applied extender. The earliest significant changes were noted in sperm motility parameters. In conclusion, European red deer spermatozoa can be stored in the epididymides at 5 °C for up to 96 h, but their biological parameters are more effectively preserved during liquid storage.

Fluorescence Microscopy and Flow-Cytometry Assessment of Substructures in European Red Deer Epididymal Spermatozoa after Cryopreservation

Thawed spermatozoa, sampled post mortem from the fresh epididymides of European red deer and epididymides stored for up to 12 h at 2–4 °C, were evaluated by fluorescence microscopy (FM) and flow cytometry (FC). The sperm samples were extended and cryopreserved. The sperm motility (CASA), sperm viability (SYBR+/PI-), acrosome integrity, mitochondrial activity, apoptotic changes, and chromatin stability were assessed. Sperm were analyzed by FM before cryopreservation, and by FM and FC after thawing. Epididymal storage time (for 12 h) had no significant effect (p > 0.05) on the examined variables before cryopreservation. After thawing, the storage variants differed (p ˂ 0.05) in the percentage of apoptotic sperm (FM and FC) and DNA integrity (FC). The results of FM and FC differed (p ˂ 0.05) in all the analyzed parameters, excluding SYBR+/PI. Significant correlations (p ˂ 0.01) were observed between the sperm viability, acrosome integrity, and the percentage of non-apoptotic spermatozoa, regardless of the applied technique. In FM, the above parameters were also significantly correlated with mitochondrial activity. The study demonstrated that European red deer spermatozoa stored in the epididymides at 2–4 °C for 12 h can be used for cryopreservation. Both techniques were equally reliable, but FM was better suited for evaluating mitochondrial activity whereas FC was more useful in the evaluation of DNA fragmentation.

Freezing Protocol Optimization for Iberian Red Deer (Cervus elaphus hispanicus) Epididymal Sperm under Field Conditions

Creating germplasm banks of wild species, such as the Iberian red Deer (Cervus elaphus hispanicus) can be challenging. One of the main difficulties is the obtention and cryopreservation of good-quality reproductive cells when the spermatozoa are obtained from epididymides after death. To avoid a loss of seminal quality during transport, developing alternative methods for cooling and freezing sperm samples under field conditions is necessary. The objective of this study was to evaluate the effects of different durations of equilibrium and different techniques of cooling and freezing on Iberian red deer epididymal sperm quality after thawing to optimize the processing conditions in this species. Three experiments were carried out: (I) evaluation of refrigeration in straws or tubes of 15 mL; (II) study of equilibration period (0, 30, 60, or 120 min); and (III) comparison of four freezing techniques (liquid nitrogen vapor in a tank (C), liquid nitrogen vapor in a polystyrene box (B), dry ice (DY), and placing straws on a solid metallic plate floating on the surface of liquid nitrogen (MP)). For all experiments, sperm motility and kinematic parameters, acrosomal integrity, sperm viability, mitochondrial membrane potential, and DNA integrity were evaluated after thawing. All statistical analyses were performed by GLM-ANOVA analysis. Samples refrigerated in straws showed higher values (p ≤ 0.05) for mitochondrial activity and lower values (p ≤ 0.05) for apoptotic cells. Moreover, the acrosome integrity showed significant differences (p ≤ 0.05) between 0 and 120 min, but not between 30 and 60 min, of equilibration. Finally, no significant differences were found between freezing in liquid nitrogen vapors in a tank or in a box, although there was a low quality after thawing when the samples were cryopreserved in dry ice or by placing straws on a solid metallic plate floating on the surface of liquid nitrogen. In conclusion, under field conditions, it would be possible to refrigerate the sperm samples by storing them in straws with a 120 min equilibration period and freezing them in liquid nitrogen vapors in a tank or box.

Embryo production by in vitro fertilization in wild ungulates: progress and perspectives

Wild ungulates are of fundamental importance for balancing ecosystems, as well as being the species of economic interest. Increasing concern over the accelerated population reduction of these species has resulted in the development of assisted reproduction techniques, such as in vitro fertilization (IVF), as a tool for conservation and multiplication. In the present scenario, IVF protocols were developed based on the methodologies used for domestic ungulates. Nevertheless, owing to the physiological and reproductive differences among the species, several factors associated with IVF and its relationship with the characteristics of the species of interest require clarification. In vitro conditions for the collection and selection of female and male gametes, oocyte maturation, sperm capacitation, co-incubation of gametes, and embryonic development can influence IVF results. Therefore, the present review considers the main advances in the methodologies already used for wild ungulates, emphasizing the strategies for improving the protocols to obtain better efficiency rates. Additionally, we discuss the conditions of each IVF stage, with emphasis on aspects related to in vitro manipulation and comparability with the protocols for domestic ungulates.

Recent Progress in Spermatology Contributing to the Knowledge and Conservation of Rare and Endangered Species

There is a remarkable diversity in the animal kingdom regarding mechanisms underlying the production, maturation, structure, and function of sperm cells. Spermatology studies contribute to the knowledge of species diversity and also provide information about individual or population fitness. Furthermore, this fundamental research is required before collected spermatozoa can be used for conservation breeding, including assisted reproduction and cryobanking. This article aims to (a) review the most recent knowledge on sperm morphology and function in wild animal species, (b) analyze how this knowledge can be used to save species in their natural habitat or ex situ, and (c) propose future scientific directions in wildlife spermatology that could positively impact animal conservation. Variations in sperm structure and performance within and between species have multiple origins and significance. This collective body of knowledge enables the design and implementation of conservation strategies and action plans that integrate several disciplines. Expected final online publication date for the Annual Review of Animal Biosciences, Volume 10 is February 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Assisted Reproductive Technology in Neotropical Deer: A Model Approach to Preserving Genetic Diversity

Simple Summary

Deer species in the Neotropical region have undergone a decline of their populations. Although conservation of their natural habitat is considered the best way to assist the species, the speed of occupation of these areas and the anthropic actions are so fast that the efforts are, at times, insufficient. As free-living populations decrease, there is a descent in the genetic diversity and an increase in crossbreeding between related individuals (inbreeding). Genetic diversity is essential for survival, since it enables natural selection to occur, providing adaptation and maintenance of the species. To protect the genetic diversity, it is possible to use reproductive techniques and conserve different types of cells, which can be used in the future to reestablish any alleles that have been lost by the populations.

Abstract

One of the most significant challenges in deer is the ability to maintain genetic diversity, avoiding inbreeding and sustaining population health and reproduction. Although our general knowledge of reproductive physiology is improving, it appears that the application of assisted reproductive technology (ART) will more efficiently advance wildlife conservation efforts and preserve genetic diversity. The purpose of this review is to present the most important results obtained with the use of ART in Neotropical deer. Thus, the state-of-the-art for estrus synchronization, semen technology, artificial insemination, and in vivo embryo production will be presented. In vitro embryo production (IVP) is also a biotechnology that is taking initial steps in deer. In this aspect, the approach with the proteomics of ovarian follicular fluid is being used as a tool for a better understanding of oocyte maturation. Finally, cell banks and the use of interspecific somatic cell nuclear transfer (iSCNT) as well as the use of stem cells for gametes differentiation are promising techniques.

Collection and in vitro maturation of Mazama gouazoubira (brown brocket deer) oocytes obtained after ovarian stimulation

In vitro production of embryos has gained prominence as a tool for use in wildlife conservation programmes in situ and ex situ. However, the development of this technique depends on steps that include ovarian stimulation, collection and oocyte maturation. The purpose of this study was to assess the feasibility of an ovarian stimulation protocol for follicular aspiration, the efficiency of videolaparoscopy for follicular aspiration and test a medium for in vitro oocyte maturation for the species Mazama gouazoubira. Five females were submitted to repeated ovarian stimulation (hormone protocol using controlled internal drug release), and estradiol benzoate on D0 and eight injections of follicle-stimulating hormone, once every 12 h, from D4 onwards at 30-day intervals. Fourteen surgical procedures were performed in superstimulated females, resulting in the collection of 94 oocytes and an average of 17.1 ± 9.1 follicles observed, 13.5 ± 6.6 follicles aspirated and 7.2 ± 3.7 oocytes collected per surgery. After collection, the oocytes were submitted to in vitro maturation for 24 h and stained with Hoechst 33342 dye to evaluate their nuclear status; 64.5% of the oocytes reached MII and 16.1% were spontaneously activated by parthenogenesis. The nuclear status of oocytes that did not undergo in vitro maturation was evaluated; 80.9% were found to be immature.

Post-mortem recovery, in vitro maturation and fertilization of fallow deer (Dama dama, Linnaeus 1758) oocytes collected during reproductive and no reproductive season

Habitat degradation leads to small and fragmented populations, lower genetic variability and fertility overtime. Assisted reproductive techniques represent important tools to cope with the dramatic loss of biodiversity. Fallow deer (Dama dama), beyond its high commercial value and wide distribution, may represent the most suitable model to study endangered cervids. In this study, oocytes were recovered post-mortem from fallow deer during the breeding and no breeding seasons and were in vitro matured (IVM). The ability of cryopreserved thawed sperm samples recovered by electroejaculation from four adult males was tested by in vitro fertilization of IVM oocytes. The number of oocytes collected per ovary did significantly vary across seasons from 6.2 ± 0.92 during breeding season to 10.4 ± 1.26 during no breeding season (p = .006). Oocytes collected during the breeding season showed higher in vitro fertilization rate compared to the no breeding season (p = .045). However, no embryos reached the blastocyst stage. Semen samples obtained by electroejaculation were successfully cryopreserved, although the cryopreservation process negatively affected most kinetic parameters, mainly at 2 hr post-thawing. Moreover, the percentage of rapid spermatozoa significantly decreased between fresh samples and at 2 hr post-thawing, whereas the percentage of slow spermatozoa increased across the same period (p < .05). Our study provides the logistic steps for the application of assisted reproductive techniques in fallow deer and might be of great interest for genetic resource bank planning.

Assisted reproductive technologies for endangered species conservation: developing sophisticated protocols with limited access to animals with unique reproductive mechanisms

Assisted reproductive technologies (ARTs) have been proposed as a means of overcoming the significant challenges of managing small, isolated populations of endangered species in zoos. However, efficient protocols for ARTs do not exist for most endangered species. This review will focus on research efforts to characterize unique reproductive mechanisms and develop species-specific ARTs. Central to these studies are assays to measure steroid metabolites in urine or feces and/or training programs to allow unrestrained blood collections and ultrasound evaluations. The resulting information about estrous cycle dynamics, combined with studies of semen collection and processing, provides the foundation for the development of artificial insemination (AI). In vitro fertilization and embryo transfer are also discussed in relation to the advantages these techniques could provide relative to AI, as well as the significant challenges involved with technologies that require oocytes and embryos. Finally, an argument is made for additional research of nontraditional model species (e.g., domestic cats and dogs) and the development of novel models representing unique taxa. Whether these species are studied by zoo-based researchers with the expressed intent of developing ARTs for conservation or academic scientists interested in basic biology, the resulting information will provide a unique, evolutionary perspective on reproduction that could have wide-reaching benefits. The more information we have available, the better our chances will be of developing effective ARTs and making a difference in conservation efforts for endangered species.

In Vitro Culture of Deer Embryos

In vitro embryo production of deer species has the potential to increase valuable traits for the agricultural sector, and from a conservation perspective, it is a propagation tool which can improve genetic diversity in small captive populations. In vitro embryo production is a multistep process consisting of oocyte maturation, fertilization, and embryo culture. These techniques provide the backbone for more advanced assisted reproductive technologies such as intracytoplasmic sperm injection (ICSI), somatic cell nuclear transfer (SCNT), a source of embryonic stem cells, and embryos for gene editing. In vitro-produced embryos are a readily available resource for comparative embryology studies and a functional assay to assess oocyte competence and evaluate in vitro embryo requirements during culture. A semidefined fertilization and culture medium system, deer synthetic oviduct fluid (DSOF), has been formulated based on deer oviduct fluid. Red deer calves (Cervus elaphus) and Thamin Eld's deer fawn (Rucervus eldii thamin) have been produced after the transfer of in vitro embryos (IVF and SCNT) grown in DSOF culture. Here we describe the in vitro method of maturation, fertilization, and embryo culture for deer species.

Integrating fertility preservation and cryo-banking into the conservation of rare and endangered deer species

More than 50 deer species live in diverse ecosystems around the world. Unfortunately, most of them are threatened or endangered because of over-hunting, poaching or habitat destruction. Protection of wild populations (in situ) and management of animal collections in zoos and breeding centres (ex situ) are complementary conservation efforts relying on multidisciplinary approaches. Reproductive biology of deer species is one of the critical areas that still needs to be thoroughly studied to ensure the success of in situ or ex situ programs. Interestingly, there is a vast diversity in reproductive traits within the deer family (from anatomy to breeding-season patterns). On the basis of this fundamental knowledge, adapted reproductive biotechnologies have been developed to enhance reproduction and preserve fertility of individuals. Early works on artificial insemination (AI), in vitro fertilisation (IVF), and germplasm freezing in the more common red deer, sika deer and white-tailed deer have been highly inspiring to projects aiming at saving endangered deer species. A few fawn births following AI or IVF using frozen semen have been reported in wild species (e.g. Eld’s deer, Rucervus eldii thamin); however, assisted reproductive techniques and cryo-banking are currently not integrated into the management of rare and endangered populations. Knowing that many deer populations are rapidly declining in situ and ex situ, there is now an urgent need for better strategies and more fertility preservation options. The objectives of the present article are to review (1) existing reproductive biotechnologies to preserve fertility of different deer species and (2) how to integrate these approaches into the management of rare and endangered populations to address conservation issues.

Oocyte holding in the Iberian red deer (Cervus elaphus hispanicus): Effect of initial oocyte quality and epidermal growth factor addition on in vitro maturation

Current in vitro embryo production protocols in the Iberian red deer (Cervus elaphus hispanicus) need to be optimized; oocyte harvesting in situ followed by overnight holding could reduce the human effort and shipping costs. In our work, post-mortem ovaries were retrieved, and the oocytes were harvested and allocated to G1 group (good quality) or G2 + G3 group (low quality). The oocytes were separately subjected to immediate in vitro maturation (IVM) or held overnight in a holding medium composed of 40% of TCM 199 with Earle's salts, 40% TCM 199 with Hanks' salts and 20% fetal bovine serum (FBS), at room temperature (16 hr). In vitro maturation was carried out in a basal medium supplemented or not with 50 ng/ml of epidermal growth factor (EGF). Our data showed that addition of EGF to the maturation medium increases the percentage of G1 oocytes reaching metaphase II (3.9% vs. 50%, basal vs. EGF; p < .001) and decreased their degeneration rate (69.9% vs. 22.2%, basal vs. EGF; p < .01) when oocytes were immediately matured. Overnight holding increased the meiotic competence of G1 oocytes (37.5% matured in basal medium) and EGF increased prophase arrest in G2 + G3 oocytes (16.1% vs. 38.8% in germinal vesicle [GV] stage in basal medium vs. EGF added medium; p < .05). Our data demonstrate that oocyte holding can be used in Iberian red deer oocytes. Interestingly, EGF addition increases the oocytes' meiotic competence in immediately matured oocytes but not after oocyte holding depending upon initial oocyte quality.

In vitro-production of embryos using immature oocytes collected transvaginally from superstimulated wood bison (Bison bison athabascae)

Two experiments were done to test the hypothesis that morphologic characteristics of wood bison cumulus-oocyte complexes (COC) are reflective of the ability of the oocyte to develop to an advanced embryonic stage after in vitro maturation, fertilization and culture, and to determine the effect of prolonging the interval from the end of superstimulation treatment to oocyte collection (FSH starvation period). Experiments were done during the anovulatory season. In Experiment 1, ovarian superstimulation was induced in 10 bison with two doses of FSH given at 48 h intervals beginning at the time of follicular wave emergence. COC were collected 3 days (72 h) after the last dose of FSH by follicular aspiration and classified as compact, expanded or denuded. The COC were matured in vitro for 24 h before fertilization in vitro (Day 0). Embryo development was assessed on Days 3, 7 and 8. The blastocyst rate was 7/34, 2/10 and 0/3 in COC classified as compact, expanded and denuded, respectively; however, only compact COC resulted in embryos that reached the expanded blastocyst stage. In Experiment 2, COC were collected at either 3 or 4 days (72 or 96 h) after the last dose of FSH (n = 16 bison/group) to determine the effect of the duration of FSH starvation on oocyte competence. The COC were classified as compact good (>3 layers of cumulus cells), compact regular (1-3 layers of cumulus cells), expanded or denuded, and then matured, fertilized and cultured in vitro. Although follicles were larger (P < 0.05) in the 4-day FSH starvation group, there was no effect of starvation period on the distribution of COC morphology; overall, 112/194 (57.7%) were compact, 29/194 (26.3%) were expanded, 39/194 (20.1%) were denuded, and 14/194 (7.2%) were degenerated (P < 0.05). Similarly, there was no effect of starvation period on embryo development. Compact good COC had the highest cleavage (88%) and blastocyst rates (54%; P < 0.05), followed by compact regular COC at 73% and 25%, respectively. Expanded and denuded COC had low cleavage (40% vs. 59%, respectively) and blastocyst rates (5% vs. 8%, respectively). We conclude that morphologic characteristics of wood bison COC are reflective of the ability of the oocyte to develop into an embryo in vitro. Importantly, oocytes collected from superstimulated bison during the anovulatory season were competent to develop to the blastocyst stage following in vitro maturation, fertilization and culture.

The impact of ovarian stimulation protocol on oocyte quality, subsequent in vitro embryo development, and pregnancy after transfer to recipients in Eld's deer (Rucervus eldii thamin)

Propagating genetically valuable individuals through oocyte collection, in vitro fertilization (IVF) and embryo transfer is critical to maintain sustainable populations of the endangered Eld's deer. The objectives of this study were to assess the impact of exogenous FSH injections on (1) the number and in vitro competence of oocytes collected and (2) the developmental potential of resulting IVF embryos after transfer into recipients during the breeding season (February-April). In a pilot experiment, estrus synchronization was conducted in three surplus females (using intravaginal progesterone-releasing devices, CIDRG for 14 days and injections of buserelin (a GnRH agonist). Five days after CIDR removal, ovaries were excised, minced and a total of 133 oocytes were recovered. Following in vitro maturation (IVM) and IVF, 63% of the oocytes formed embryos but only 5% reached the blastocyst stage. In a subsequent study, follicle numbers and diameters were compared between synchronized does stimulated with 0 or 80 mg FSH (-FSH and +FSH; n = 8 does in each group) and oocytes collected either by laparoscopic ovum pick-up or ovariectomy. FSH stimulation increased the main follicular diameter from 2-3 mm to 4-5 mm (P < 0.05) but not the oocyte number (∼20/donor) or the percentage of good quality oocytes (57%) regardless of the treatment. FSH stimulation did not either affect the percentage of cleaved embryos after IVF (25-35%; P > 0.05). Lastly, embryos at the 2-to 8-cell stage (from either + FSH or -FSH groups) were transferred into the oviducts of 11 synchronized recipients. With the +FSH embryos, three pregnancies failed between 90 and 120 days of gestation and two fawns that were born preterm (Days 215 and 224 of gestation) died at birth. In the -FSH group one healthy female fawn was born on Day 234 of gestation. This is the first report of a successful in vitro embryo production and subsequent birth of a live Eld's deer fawn. Further investigations are required to improve IVM/IVF success and the developmental potential of the embryos.

Selection of red deer spermatozoa with different cryoresistance using density gradients

The objective of sperm selection media is selecting the best spermatozoa and to remove seminal plasma and diluent for using them in assisted reproductive techniques. It is known that individuals show different cryoresistance in response to the same freezing procedure. Our hypothesis was that the efficacy of selection media could be dissimilar for samples with different sperm quality after thawing. Epididymal sperm samples from mature Iberian red deer were collected and frozen. Males were classified as with high post-thaw sperm quality when sperm motility (SM) ≥ 70%, or as with low post-thaw sperm quality when SM ≤ 69%. Samples were centrifuged using the following density gradients (DG): Percoll^® , Puresperm^® and Bovipure^™ , and several functional sperm parameters were assessed after sperm selecting and washing. Males classified with high sperm quality had higher post-thawing values (p > .05) for all parameters evaluated, except for linearity index, than those categorized as low sperm quality. After selection, some sperm characteristics improved (viability, apoptosis and mitochondrial activity) for both groups, showing the males with high sperm quality higher values in all sperm parameters except for kinematic traits and DNA fragmentation index (%DFI), regardless of DG. Bovipure^™ yield lower values of sperm motility, viability, apoptosis and mitochondrial activity in relation to Percoll^® and Puresperm^® considering both quality groups. There was an interaction between the type of DG and sperm quality group for sperm viability (p = .040) and apoptosis (p = .003). Thus, Percoll^® selected less live and more apoptotic spermatozoa than Puresperm^® and Bovipure^™ for males with low sperm quality. In conclusion, the DG are more efficient selecting spermatozoa from samples with high sperm quality, acting differently depending on initial sperm quality.

Morphological defects of epididymal spermatozoa in male roe deer (Capreolus capreolus) during the reproductive season

The aim of this study was to analyse the morphology of the epididymal spermatozoa of male roe deer obtained postmortem at the beginning (May), peak (July/August) and the end (September) of the reproductive season. Spermatozoal abnormalities were divided into major (associated with impaired fertility) and minor (not associated with impaired fertility) defects. The highest percentage of abnormal spermatozoa was observed in May (17.78 ± 1.88%), with a much higher proportion of major (12.35 ± 1.11%) than minor defects (5.43 ± 1.59%) being observed. The percentage of abnormal spermatozoa was lowest during the peak of the reproductive season (4.97 ± 1.13%), with the proportion of major (2.68 ± 0.78%) and minor defects (2.28 ± 0.45%) being comparable during this period. The percentage of abnormal spermatozoa increased again in September (11.05 ± 1.60%), with the major defects (6.15 ± 1.04%) slightly surpassing the minor defects (4.90 ± 0.77%); however, total abnormalities still remained lower than those found in May. These differences were statistically significant, with the exception of the difference in minor defects between the pre-rut and post-rut periods. These results indicate that the best period to collect epididymal spermatozoa from roe deer postmortem is the peak of the reproductive season (July/August); however, they can also be recovered at the end of the reproductive season (September), as the percentage of major defects is relatively low at this time. This study provides the basis for further research to determine optimal methods for the storage and cryopreservation of epididymal spermatozoa in this species.

Complete mitochondrial genome of a wild Alashan Red Deer (Cervus elaphus alxaicus)

The complete mitochondrial genome of a wild red deer from Helan Mountain, China was sequenced and annotated newly. The total length of the mitochondrial genome is 16,428 bp, with a base composition of 33.3% A, 28.8% T, 24.4% C and 13.5% G, and it contains 12S rRNA gene, 16S rRNA gene, 22 tRNA genes, 13 protein-coding genes and 1 control region.

Influence of recovery method and centrifugation on epididymal sperm from collared peccaries (Pecari tajacu Linnaeus, 1758)

In order to establish protocols for gamete recovery from accidentally killed wild animals, or to take advantage of those slaughtered by captive breeders, we assess the influence of two methods on the recovery of epididymal sperm from collared peccaries, and verify the effect of centrifugation on such gametes. Genitalia from nine animals were used. For each animal, one epididymis was processed by flotation and the other was processed by retrograde flushing, both using a buffered media based on Tris. Following recovery, sperm were evaluated for motility, vigor, viability, functional membrane integrity, and morphology. A 1-mL aliquot of each sample was centrifuged, the supernatant removed, and the pellet suspended and evaluated as fresh samples. The sperm characteristics did not differ between the samples collected by flotation or retrograde flushing (P < 0.05). Centrifugation promoted an increase in head and tail defects, thus reducing the percentage of viable sperm (P < 0.05). No other parameter assessed for both methods was affected by centrifugation. In conclusion, epididymal sperm from collared peccaries can be efficiently collected through flotation or retrograde flushing, but not when either is followed by centrifugation.

The role of chromosome variation in the speciation of the red brocket deer complex: the study of reproductive isolation in females

BACKGROUND

The red brocket deer, Mazama americana, has at least six distinct karyotypes in different regions of South America that suggest the existence of various species that are today all referred to as M. americana. From an evolutionary perspective, the red brockets are a relatively recent clade that has gone through intense diversification. This study sought to prove the existence of post-zygotic reproductive isolation in deer offspring between distinct chromosome lineages. To achieve this, inter-cytotype and intra-cytotype crosses were performed, which resulted in both F1 hybrid (n = 5) and pure offspring (n = 3) in captivity.

RESULTS

F1 females were analyzed in terms of their karyotypes, ovarian histology, estrous cycles and in vitro embryo production. Pure females presented parameters that were similar to those previously reported for M. Americana; however, the parameters for hybrid females were different. Two hybrids were determined to be sterile, while the remaining hybrids presented characteristics of subfertility.

CONCLUSIONS

The results support the existence of well-established reproductive isolation among the most distant karyotype lineages and elucidates the need to define all karyotype variants and their geographical ranges in order to define the number of species of red brocket.

Intracytoplasmic sperm injection (ICSI) in small ruminants

Small ruminants are an important component of the global production systems of meat and wool, and their reproductive biology is well known. However, the incorporation of assisted reproduction techniques (ART) in the production systems of small ruminants is not as well developed as for other domestic species. Normally, production systems that incorporate ARTs are restricted to artificial insemination or in vivo embryo transfer. Intracytoplasmic sperm injection (ICSI) is one of the ARTs techniques reported for small ruminants and consists of the injection of spermatozoa inside an oocyte, bypassing the natural process of sperm-oocyte interaction. In goats and sheep, there are few live births by ICSI reported, with no reports from other species of small ruminants. Currently, there has not been intensive research about ICSI in small ruminants. However, ICSI has potentially important applications in animal production systems, primarily its use with semen of valued animals, with epididymal sperm, in the fertilization of prepubertal or cryopreserved oocytes. Other applications include more advanced techniques, such as transgenic-ICSI or its combination with spermatogonial transplantation. In this article, we review the "state of the art" of this technique in small ruminants including its historical development, research needs for its improvement and future applications.

Increasing age influences uterine integrity, but not ovarian function or oocyte quality, in the cheetah (Acinonyx jubatus)

Although the cheetah (Acinonyx jubatus) routinely lives for more than 12 yr in ex situ collections, females older than 8 yr reproduce infrequently. We tested the hypothesis that reproduction is compromised in older female cheetahs due to a combination of disrupted gonadal, oocyte, and uterine function/integrity. Specifically, we assessed 1) ovarian response to gonadotropins; 2) oocyte meiotic, fertilization, and developmental competence; and 3) uterine morphology in three age classes of cheetahs (young, 2-5 yr, n = 17; prime, 6-8 yr, n = 8; older, 9-15 yr, n = 9). Ovarian activity was stimulated with a combination of equine chorionic gonadotropin and human chorionic gonadotropin (hCG), and fecal samples were collected for 45 days before gonadotropin treatment and for 30 days after oocyte recovery by laparoscopy. Twenty-six to thirty hours post-hCG, uterine morphology was examined by ultrasound, ovarian follicular size determined by laparoscopy, and aspirated oocytes assessed for nuclear status or inseminated in vitro. Although no influence of age on fecal hormone concentrations or gross uterine morphology was found (P > 0.05), older females produced fewer (P < 0.05) total antral follicles and oocytes compared to younger counterparts. Regardless of donor age, oocytes had equivalent (P > 0.05) nuclear status and ability to reach metaphase II and fertilize in vitro. A histological assessment of voucher specimens revealed an age-related influence on uterine tissue integrity, with more than 87% and more than 56% of older females experiencing endometrial hyperplasia and severe pathologies, respectively. Our collective findings reveal that lower reproductive success in older cheetahs appears to be minimally influenced by ovarian and gamete aging and subsequent dysfunction. Rather, ovaries from older females are responsive to gonadotropins, produce normative estradiol/progestogen concentrations, and develop follicles containing oocytes with the capacity to mature and be fertilized. A more likely cause of reduced fertility may be the high prevalence of uterine endometrial hyperplasia and related pathologies. The discovery that a significant proportion of oocytes from older females have developmental capacity in vitro suggests that in vitro fertilization and embryo transfer may be useful for "rescuing" the genome of older, nonreproductive cheetahs.

Oocyte quality and estradiol supplementation affect in vitro maturation success in the white-tailed deer (Odocoileus virginianus)

White-tailed deer oocyte biology is not well documented. The objective of this study was to determine (1) the influence of estradiol (E(2)) supplementation on meiotic resumption and the ability to "rescue" poorer quality (lower grade) oocytes and (2) the kinetics of oocyte nuclear maturation in vitro in the white-tailed deer. In Experiment 1, immature oocytes harvested during hunting-culling operations were cultured for 24h in the presence or absence of E(2). Incubation in 1mug/mL E(2) promoted nuclear maturation (to telophase I, TI; or to metaphase II, MII) in a higher proportion of Grade 1 oocytes ( approximately 77%; P<0.05) compared with that in Grade 2 or Grade 3 counterparts ( approximately 51%). For Grades 2 and 3 oocytes, there was no advantage (P>0.05) for E(2) supplementation in reaching TI/MII. In Experiment 2, Grade 1 oocytes were cultured in the presence of E(2) and nuclear status evaluated at 0, 3, 6, 12, and 24h of in vitro incubation. At 0h,>70% of oocytes already had undergone germinal vesicle breakdown. After 12h, approximately 70% of oocytes had reached metaphase I of nuclear maturation, with approximately 75% achieving TI/MII by 24h in vitro. In summary, adding E(2) to an in vitro maturation (IVM) culture system for white-tailed deer was advantageous, but only for the highest quality oocytes, with approximately 75% achieving nuclear maturation. In contrast, E(2) supplement did not benefit lower-grade oocytes, half of which will reach MII, with the other half failing. Under the described culture conditions, good-quality white-tailed deer oocytes achieve nuclear maturation over a time duration comparable with that reported in other ungulates.

Sperm parameters on Iberian red deer: electroejaculation and post-mortem collection

Artificial reproductive technologies (ART) for cervids have improved, but a need remains for the collection of basic data. We studied two models of sperm collection in Iberian red deer, post-mortem (PM) in a wild population (179 samples) and by electroejaculation (EE) in a farmed population (37 samples), recording: testicular and epididymal weight, testicular diameter, sperm quantity, pH and osmolality and spermatozoa quality (motility by CASA, abnormal forms, cytoplasmic droplets, viability and acrosomal status). We tested the relationship of these parameters with stag age and compared the two models (PM and EE; medians showed). Genitalia parameters were linearly related to stag age (testicular diameter: 31.5-50.5mm for 2-9 years). Total number of spermatozoa collected were PM: 2.5x10(9) and EE: 3.6x10(9) (P>0.05), increasing with age only for PM. We found a positive relationship between testicular size and spermatozoa collected for PM. Osmolality and pH were PM: 6.28 and 378mOsm/kg; EE: 7.63 and 309mOsm/kg (P<0.05). The pH increased with age only for EE. Percentage of motile spermatozoa was similar for PM and EE, but motility quality was lower for PM. Abnormal forms, proximal and distal droplets were lower for EE (22%, 1.3%, 1.5% vs. PM: 23%, 4.3%, 83%). Viability was similar (74%) and intact acrosomes were higher for EE (97% vs. 89%). Both PM and EE samples could be used for germplasm banking. This study contributes with new data on red deer spermatology and for the development of ART in cervids.

The temporal relationship between oocyte maturation and early fertilisation events in relation to the pre-ovulatory LH peak and preimplantation embryo development in red deer (Cervus elaphus)

The temporal relationships among oocyte maturation, gamete transport and fertilisation following the pre-ovulatory luteinsing hormone surge in red deer were established; and secondly, early preimplantation development to the blastocyst stage in relation to the onset of oestrus was determined for red deer. In the first series of observations, oestrus was synchronised in April (N=22), for the fixed time recovery of gametes from 0 to 36 h after the estimated pre-ovulatory LH peak. Matings were observed and the time of the LH peak was determined from the retrospective analysis of blood plasma collected at 3h intervals. Gametes were recovered surgically and the meiotic status of follicular and ovulated oocytes assessed. Spermatozoa were recovered from the oviduct and their motility analysed by videomicroscopy. Nineteen of 22 hinds exhibited a pre-ovulatory LH surge and were observed to mate. Oocyte metaphase I occurred between 11 and 18 h, and metaphase II was completed within the follicle between 20 and 25 h following the pre-ovulatory LH peak. Fertilised ova were recovered from 30 to 36 h in both the ampulla and isthmic portions of the oviduct. Motile spermatozoa were first recovered from the isthmus and the ampulla at 13 and 21 h, respectively, after the LH peak. Hyperactive spermatozoa were observed in both the isthmus and the ampulla flushings but only from the eight hinds that had ovulated. In the second series of observations, 16 mature hinds were synchronised and allocated to groups for embryo collection on days 3, 5 and 7 after oestrus. Eight embryos were recovered; an 8-cell at 90 h, 3 morulae at 137, 138 and 186 h, and 4 blastocysts at 180, 182 and 190 h post-mating. Blastocysts were only recovered from the uterine horns and the mean+/-S.E.M. number of nuclei per blastocyst was 93.5+/-10.0 with a range of 66-114 cells. The results of this study will improve the application of assisted reproductive technologies to red deer as they indicate that oocyte maturation, fertilisation and early embryonic development of the red deer is similar to other domestic ruminants with the exception that the red deer embryo enters the uterus at the blastocyst stage.

In vitro oocyte maturation, fertilization and culture after ovum pick-up in an endangered gazelle (Gazella dama mhorr)

The recovery of immature oocytes followed by in vitro maturation, fertilization and culture (IVMFC) allows the rescue of biological material of great genetic value for the establishment of genetic resource banks of endangered species. Studies exist on sperm cryopreservation of endangered Mohor gazelle (Gazella dama mhorr), but no work has been carried out yet on oocyte collection, fertilization and culture in this or related species. The purpose of this study was to develop a protocol for ovarian stimulation for the recovery of oocytes and subsequent IVMFC in the Mohor gazelle using frozen-thawed spermatozoa. Ovum pick-up was performed after ovarian stimulation with a total dose of 5.28 mg of ovine FSH. A total of 35 oocytes were recovered from 56 punctured follicles (62%) (N=6 females). Out of 29 cumulus-oocyte complexes matured in vitro, 3% were found at germinal vesicle stage, 7% at metaphase I, 21% were degenerated, and 69% advanced to metaphase II. Fertilization and cleavage rates of matured oocytes were 40 and 30%, respectively. Embryos cleaved in vitro up to the 6-8 cell stage but none progressed to the blastocyst stage, suggesting the existence of a developmental block and the need to improve culture conditions. Although more studies are needed to improve hormonal stimulation and oocyte harvesting, as well as IVMFC conditions, this study demonstrates for the first time the feasibility of in vitro fertilization with frozen-thawed semen of in vitro matured oocytes collected by ovum pick-up from FSH-stimulated endangered gazelles.

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.

Cryopreservation of Iberian red deer (Cervus elaphus hispanicus) epididymal spermatozoa: Effects of egg yolk, glycerol and cooling rate

Two experiments were conducted to determine the effects of egg yolk (EY), glycerol, and cooling rate on the cryosurvival of red deer epididymal spermatozoa. The aim of Experiment 1 was to examine the effects of two EY types (clarified EY, CE, prepared by centrifugation, and whole EY, WE), and four EY concentrations (0, 5, 10 and 20%) on cryosurvival of red deer epididymal spermatozoa. Sperm samples were diluted to a final sperm concentration of approximately 200 x 10(6)spermatozoa/ml with a Tris-citrate-fructose-EY extender (TCF) prior to freezing. Sperm cryosurvival was judged in vitro by microscopic assessments of individual sperm motility, viability and of plasma membrane (by means of the HOS test) and acrosome (NAR) integrities. Cryopreservation of red deer epididymal spermatozoa frozen in a clarified EY extender, and with a 20% EY resulted in more vigorous post-thaw and post-incubation motilities (P<0.0001). Moreover, our results showed that regardless of the egg yolk concentration tested, the best sperm quality was obtained with the use of CE. Therefore, the objective of Experiment 2 was to explore the post-thaw effects of four clarified egg yolk concentrations (0, 5, 10 and 20%), two final glycerol concentrations (3 and 6%), and two cooling rates from 22 to 5 degrees C (slow: 0.23 degrees C/min; rapid: 4.2 degrees C/min) on red deer epididymal spermatozoa. At thawing, the effects of CE and glycerol concentrations, and cooling rate, all independently affected post-thaw sperm quality, while there were no effects of interactions on post-thawing sperm quality. Therefore, we studied each variable separately. Differences (P<0.05) for most of the semen parameters evaluated were found between the two final glycerol concentrations tested, with the high values after thawing found with the use of 6% glycerol (58.8+/-1.4 versus 46.2+/-1.4, for sperm motility). Moreover, the cooling rate did not have an effect on the semen characteristics, except for NAR (P<0.05), with the high values after thawing found with the use of the rapid protocol (64.5+/-1.4 versus 59.9+/-1.4). In conclusion, the use of 20% CE and 6% glycerol in combination with a rapid cooling rate, significantly improved red deer epididymal spermatozoa freezability.

The Application of Reproductive Technologies to Natural Populations of Red Deer

Over the past decade, there has been increasing interest in the application of reproductive technology to the conservation and management of natural populations of deer. The application of assisted reproduction technologies within natural population of deer is in its infancy. However, its future potential is enormous, particularly in relation to genetic management or conservation. This paper reviews the present state of such technologies for a wild subspecies of red deer, the Iberian red deer (Cervus elaphus hispanicus), by discussing the major components of oestrous synchronization, semen collection/cryopreservation and insemination techniques. In addition, findings made during the course of studies on natural populations have enormous potential for the understanding of novel reproductive mechanism that may not be uncovered by livestock or human studies. A summary of these results are also reviewed here.

Laparoscopic ovum pick-up and in vitro production of sika deer embryos: effect of season and culture conditions

Amongst the 200 deer subspecies worldwide, more than 40 are considered as endangered. In vitro embryo production may represent an efficient way to produce and disseminate offspring from sparse remaining individuals in these species. With a view to establishing a method of in vitro embryo production, we assessed the ovarian response after hormonal stimulation (oFSH), oocyte yield following laporoscopic ovum pick-up (LOPU) and oocyte developmental competence according to seasonal reproductive status in sika deer (Cervus nippon nippon). Twelve adult sika deer hinds were allocated between two groups and submitted weekly to oFSH follicular growth stimulation followed by LOPU. Hinds in Group A (n=6) were treated first during the breeding season (5 weeks), and then during the non-breeding season (3 weeks). Hinds in Group B (n=6) were submitted to similar procedures but in the reverse order (treated first during the non-breeding season). Cumulus-oocytes complexes (COC) recovered from Group B were allowed to mature in vitro for 24 h in TCM-199 medium supplemented with oFSH, goat follicular fluid and 100 microM cysteamine. In vitro fertilization was performed with frozen/thawed semen in SOFaa medium supplemented with 20% estrous sheep serum and presumptive zygotes were cultured in the presence or absence of ovine oviductal epithelial cell monolayer (oOEC) in SOFaa-BSA medium. Mean number of follicles aspirated per hind per session decreased significantly between breeding and non-breeding season in Group A (9.8+/-0.7 versus 3.2+/-0.7, mean+/-S.E.M., respectively, P<0.001) but did not change between the non-breeding and the subsequent breeding season in Group B (5.3+/-0.7 and 5.7+/-0.7, respectively, P>0.05). Irrespective of the season, good quality COC with complete and compact cumulus investments were recovered allowing a high cleavage rate after in vitro maturation and fertilization. Whereas development to the blastocyst stage did not occur in SOF medium alone, high development rates to the blastocyst stage were observed in oOEC co-culture regardless of season (22% and 34% of total oocytes in co-culture during non-breeding and breeding season, respectively).

Comparison of two methods for obtaining spermatozoa from the cauda epididymis of Iberian red deer

We have compared two methods for salvaging epididymal sperm from post-mortem samples from Iberian red deer. Of each pair of testicles (29 samples), one cauda epididymis was processed by means of cuts (sperm was immediately diluted with extender) and the other was detached from the corpus and flushed from the vas deferens with 1 mL of extender. Sperm was processed for cryopreservation, and analyzed just after recovery, pre-freezing and post-thawing. Total spermatozoa recovered, contamination (concentration of epididymal cells and red blood cells (RBCs)) and quality (motility by CASA, and acrosomal status, viability and mitochondrial status by flow cytometry) were used to compare both methods. The number of recovered spermatozoa was similar for both methods. Contamination was higher for the cuts method, but when considering the final dilution before freezing, only RBCs concentration was significantly higher. Motility was similar just after extraction, but higher for both pre-frozen and post-thawed flushed sperm. Pre-freezing acrosomal status (P < 0.05) and viability (P < 0.1) were better for flushing; however post-thawing results were similar for the two methods. A clustering analysis using CASA data showed that the subpopulation pattern of motile sperm was different depending on the method, being better for flushing. With regard to yield, lower contamination (especially RBCs) and, in general, better quality results, flushing seems to be a more recommendable method for post-mortem sperm recovery. The cuts method may be more practical on certain occasions, but care must be taken in order to achieve rapid extension of the sample and to avoid contamination in order to improve sample condition.

Successful use of oviduct epithelial cell coculture for in vitro production of viable red deer (Cervus elaphus) embryos

Techniques for in vitro production (IVP) of viable embryos have been thoroughly developed in several domestic species in view to improve breeding efficiency. When applied to wild life, these techniques may also help the maintenance of biodiversity through amplification of sparse animals offspring and facilitation of genetic material exchange. During the successive steps of IVP, i.e. oocyte in vitro maturation (IVM), fertilization (IVF) and early embryo development (IVD) to the blastocyst stage, gametes and embryos are faced with unusual environment, including oxidative stress, known to be detrimental to their survival. In the present study, starting from methods developed in domestic species, we have adapted IVP to produce viable red deer embryos. In a first experiment, cumulus cells were removed from in vitro matured oocytes either before or after IVF. The presence of cumulus cells during IVF did not affect final cleavage or development rates. In a second experiment, in vitro matured oocytes were fertilized in the presence of cumulus cells and cultured in SOFaaBSA medium alone or in the presence of ovine oviduct epithelial cell (oOEC) monolayer. Whereas, oviduct cells did not improve the cleavage rate, they significantly increased the rate of embryos reaching the blastocyst stage (from 3 to 25% of total oocytes). Ten blastocysts from oOEC coculture were transferred after freezing and thawing to five recipient hinds and gave rise to three pregnancies. The three pregnant hinds gave birth to three live and normal calves.

Effect of 1,2-Propanediol Versus 1,2-Ethanediol on Subsequent Oocyte Maturation, Spindle Integrity, Fertilization, and Embryo Development In Vitro in the Domestic Cat1

This study assessed the impact of various cryoprotectant (CPA) exposures on nuclear and cytoplasmic maturation in the immature cat oocyte as a prerequisite to formulating a successful cryopreservation protocol. In experiment 1, immature oocytes were exposed to 0, 0.75, 1.5, or 3.0 M of 1,2-propanediol (PrOH) or 1,2-ethanediol (EG) at room temperature (25 degrees C) or 0 degrees C for 30 min. After CPA removal and in vitro maturation, percentage of oocytes reaching metaphase II (MII) was reduced after exposure to 3.0 M PrOH at 0 degrees C or 3.0 M EG at both temperatures. All CPA exposures increased MII spindle abnormalities compared to control, except 1.5 M PrOH at 25 degrees C. In experiments 2 and 3, immature oocytes were exposed to CPA conditions yielding optimal nuclear maturation that either had caused spindle damage (0.75 M PrOH, 1.5 M EG, and 3.0 M PrOH at 25 degrees C) or not (1.5 M PrOH at 25 degrees C). After maturation and insemination in vitro, oocytes were cultured for 7 days to assess treatment influence on developmental competence. CPA exposure did not affect fertilization, but the high incidence of MII spindle abnormalities resulted in a low percentage of cleaved embryos. Blastocyst formation and quality were influenced by both CPA types (EG was more detrimental than PrOH) and concentration (3.0 M was more detrimental than 1.5 M). Overall, cat oocytes appear to be highly sensitive to CPA except after exposure to 1.5 M PrOH at 25 degrees C, a treatment that still allowed approximately 60% of the oocytes to reach MII and approximately 20% to form blastocysts.

State-of-the-art production, conservation and transfer of in-vitro-produced embryos in small ruminants

Today, although not efficient enough to replace multiple ovulation and embryo transfer, in vitro embryo production for small ruminants is a platform for new reproductive technologies, such as embryo sexing, transgenesis and cloning. The in vitro embryo-production system developed for sheep and goats is more efficient now than 15 years ago, but could still be improved. Laparoscopic collection of oocytes in live animals treated with gonadotrophin indicates a promising future for the application of this technology to genetic improvement programmes. Oocyte maturation in defined medium with epidermal growth factor and cysteamine appears as efficient as oocyte maturation in follicular fluid-supplemented medium and allows future study of the effect of other factors involved in the cytoplasmic maturation of oocytes from these species. Further efforts have to be made to standardise the semen-capacitating process and to improve the quality and freezability of in-vitro-produced (IVP) embryos. The optimisation of IVP procedures for deer species has required the study of the seasonal variation of oocyte competence and the development of a specific methodology to allow the culture of embryos up to the blastocyst stage.

Effects of thawing procedure on postthawed in vitro viability and in vivo fertility of red deer epididymal spermatozoa cryopreserved at -196 degrees C

In this study, we have determined the effects of individual factor and thawing procedure on in vitro viability and in vivo fertility of frozen-thawed red deer epididymal spermatozoa. The spermatozoa that were collected from 13 Iberian deer stags were diluted at room temperature in a Triladyl-20% egg yolk medium and frozen in nitrogen vapors. In the first experimental series, sperm samples were collected from 10 mature stags. For thawing, the frozen straws were subjected to 3 different procedures: I (37 degrees C for 20 seconds), II (60 degrees C for 8 seconds) and III (70 degrees C for 5 seconds). Sperm cryosurvival was judged in vitro by microscopic assessments of individual sperm motility (SM) and of plasma membrane and acrosome (NAR) integrities. Statistically significant variations were found (P <.05) between stags for most of the seminal parameters evaluated. The thawing procedure did not have an effect on the seminal characteristics evaluated after this process, except for SM (P <.05), with the best overall recovery rates after freezing and thawing found with the use of protocol I. Our results also show a differential resistance to return to isosmotic conditions of spermatozoa thawed using the different thawing protocols. In the second experimental series (insemination artificial trial), with spermatozoa from 3 stags, results of fertility were statistically higher (69.7% vs 42.4%, P =.014) when spermatozoa were thawed at 37 degrees C for 20 seconds than were warmed at 60 degrees C for 8 seconds. Therefore, thawing protocol I, which provides slow thawing rates, was the most beneficial for epididymal spermatozoa thawing of the cervid subspecies analyzed in this study. In summary, high in vitro survival and in vivo fertility of frozen-thawed deer epididymal spermatozoa were dependent on warming rates, but each stag exhibited its own sensitivity to cryopreservation.

Relationship between the characteristics of epididymal red deer spermatozoa and penetrability into zona-free hamster ova

A heterologous (zona-free hamster oocytes) in vitro fertilization (IVF) system was used to evaluate the relationship between sperm factors and penetration capacity of epididymal red deer spermatozoa. The sperm parameters evaluated in 36 sperm samples obtained postmortem from stags selectively shot during the rutting season were sperm motility, functional integrity of plasma membrane by means of the hypo-osmotic swelling test (HOST), and, simultaneously, viability and acrosomal status via a triple-stain technique. Zona-free hamster oocytes were used to evaluate the capacity of the different sperm assays to predict in vitro penetration. In order to increase the variability in sperm quality, we recovered samples from stags at different intervals between the death of the male and the collection of the genitalia. All measures of sperm quality declined progressively (P <.001) with increasing intervals between death and sample collection. In addition, many sperm parameters were related to penetration ability in vitro. Subsequently, sperm samples were rearranged in 2 categories according to the interval that had elapsed between death and the collection of the genitalia (group 1, short interval = 0-12 h; group 2, large interval = 18-40 hours). When samples were grouped, less correlation achieved significance, especially for group 1, than when samples were not divided. Also, correlation between the number of sperm per oocyte and sperm parameters for group 1, which had the highest values of sperm quality, failed to reach significance. It is concluded that the classical parameters accepted in assessing the viability of deer spermatozoa can be good predictors of the penetrating ability of the spermatozoa when satisfactory in vitro conditions are used for the development of the IVF system. Also, this study demonstrates that compatible heterologous gamete interaction allows thorough assessment of sperm function in a wild deer.

Recovery and cryopreservation of sika deer (Cervus nippon) spermatozoa from epididymides stored at 4 degrees C

The aim of this study is to clarify influence of cold storage of deer epididymides on sperm quality and suitability for cryopreservation. The epididymides were obtained postmortem from sika deer during the breeding season. When epididymides were removed 8-12h postmortem and stored at 4 degrees C for 1-4 days, the collected spermatozoa showed low motility (6.4%). When spermatozoa were collected from epididymides removed within 4h postmortem, sperm motility and viability were 71.8 and 82.4%, respectively. Sperm motility decreased as prolongation of the storage period of the epididymides continued up to 7 days, but sperm viability was not affected. Pyknosis of the epithelial cells and their release into the lumen were observed in the stored epididymides. Epididymal spermatozoa frozen on Day 0 showed 58.1% motility and 83.2% viability. Motility of the frozen-thawed spermatozoa from epididymides stored at 4 degrees C for 1 day (41.9%) was similar to that of nonfrozen spermatozoa from epididymides stored for 4 days (41.8%). These results suggest that refrigeration of deer epididymides or cryopreservation of spermatozoa from refrigerated epididymides can be used for assisted reproductive techniques when epididymal spermatozoa cannot be collected immediately.

New developments reproductive technologies in deer

In vitro embryo production is the platform for advanced reproductive technologies, such as cloning. The in vitro embryo production system developed for farmed red deer (Cervus elaphus) evolved along similar lines to that pioneered by other domestic species researchers. However, applying existing in vitro embryo production methods from these other species resulted in limited success and has necessitated developing a species-specific methodology for red deer based on the their physiology. Analysis of oviduct fluid led to the development of a semi-defined fertilization and culture media system, Deer Synthetic Oviduct Fluid (DSOF), which resulted in successful culture of red deer embryos to the blastocyst stage. Transvaginal ultrasound-guided ovarian examination and ovum pickup has enabled the study of seasonality constraint and propagation from selected female genetics, respectively. During the 4-month breeding season (April-July), 15% of cleaved oocytes developed to blastocysts, whereas no blastocysts developed from oocytes collected after July. The process of developing an in vitro embryo production system for farmed red deer may serve as a beneficial model for the propagation of endangered cervine species.

New commercial opportunities for advanced reproductive technologies in horses, wildlife, and companion animals

As advanced reproductive technologies become more efficient and repeatable in livestock and laboratory species, new opportunities will evolve to apply these techniques to alternative and non-traditional species. This will result in new markets requiring unique business models that address issues of animal welfare and consumer acceptance on a much different level than the livestock sector. Advanced reproductive technologies and genetic engineering will be applied to each species in innovative ways to provide breeders more alternatives for the preservation and propagation of elite animals in each sector. The commercialization of advanced reproductive techniques in these niche markets should be considered a useful tool for conservation of genetic material from endangered or unique animals as well as production of biomedical models of human disease.

Assessment of in vitro fertility of deer spermatozoa by heterologous IVF with zona-free bovine oocytes

We have previously shown that the in vitro development of deer embryos differed according to the IVF conditions. The aim of the study was to use heterologous IVF with zona-free matured bovine oocytes to assess the in vitro fertility of 3 samples of deer semen (2 ejaculates from sika deer (Cervus nippon) and 1 pool of epididymal spermatozoa from red deer (Cervus elaphus)). The frozen/thawed semen samples were selected on Percoll gradient and resuspended in Tyrode modified medium supplemented with estrus sheep serum (0, 2, 20% v/v) or heparin (10 microg/mL). During 8 h of culture, the sperm motility index according to the post-insemination time (hpi) did not differ either between samples or between supplemented IVF media. In vitro matured zona-free bovine oocytes were inseminated in different IVF media with the semen samples. Penetration rates assessed at 15 hpi were optimal with 20% estrus sheep serum for sika deer ejaculates whereas 2% were sufficient to reach the maximum functionality of epididymal spermatozoa from red deer. The mean time of pronuclear formation was similar regardless of the semen sample. The precocity of the onset of the first S-phase in both pronuclei was characterized by Bromo-deoxy-Uridine exposures between 5 and 15 hpi in order to assess the developmental potential conferred by the semen sample (intrinsic value). As we previously observed in homologous IVF, this value seemed to be higher for the epididymal sperm sample.