Semen cryopreservation in Bactrian camel (Camelus bactrianus) using SHOTOR diluent: Effects of cooling rates and glycerol concentrations

Impact of papain on the treatment of raw diluted dromedary semen

A variety of parameters, including liquefaction and semen viscosity, affect the sperm's ability to travel and reach the egg for fertilization and conception. Given that the details behind the viscosity of the semen in male camels have not yet been fully clarified, the purpose of this study was to ascertain how the addition of papain affected the viscosity of fresh diluted camel semen. The study examined semen samples derived from camels that had distinct viscosities. Sperm motility, viability, abnormal sperm percentage, concentration, viscosity, morphometry, acrosome integrity and liquefaction were among the evaluations following 0, 5, 10, 20 or 30 min of incubation at 37°C with papain (0.004 mg/mL, 0.04 mg/mL or 0.4 mg/mL; a semen sample without papain was used as a control). A statistically significant interaction between the effects of papain concentrations and incubation time was found (F = 41.68, p = .0001). Papain concentrations (p = .0001) and incubation times (p = .0001) both had a statistically significant impact on viscosity, according to a simple main effects analysis. A lower viscosity was found (p < .05) at 0.04 mg/mL (0.1 ± 0.0) after 10 min of incubation. A simple main effects analysis showed that papain concentrations and incubation time have a statistically significant effect on sperm motility (p = .0001). At 0.04 mg/mL papain, the sperm motility % was higher (p < .05) after 10 min (64.4 ± 4.8), 20 min (68.4 ± 6.2), and 30 min incubation (72.2 ± 6.6) compared to 0, 5 min (38.3 ± 4.1 and 51.6 ± 5.0, respectively). In conclusion, the fresh diluted camel semen had the lowest viscosity properties after 10 min of incubation with 0.04 mg/mL papain, without compromising sperm motility, viability, acrosome integrity and sperm morphology.

Cooled storage of semen from livestock animals (Part II): Camelids, goats, and sheep

This review is part of the Festschrift in honor of Dr. Duane Garner and provides an overview of current techniques in cooled storage of semen from livestock animals such as camelids, goats, and sheep. Facing worldwide environmental changes and a trend towards more conscious and healthy eating behaviors, the development of a stable animal breeding industry is a significant challenge for the near future. In the present review, factors influencing semen handling in camelids, goats and sheep are described and relevant methods as well as current trends to improve liquid-storage of cooled semen are discussed, including extenders, additives, cooling rates, and storage temperatures. The species-specific physiology and resulting challenges are taken into consideration. While the main problem for camelid semen processing is the relatively greater viscosity as compared with that of some other animals, the deciding factor for successful artificial insemination (AI) in goats and sheep is the site (i.e., cervical or vaginal) of semen placement in the reproductive tract. Due to the type of cervical anatomy, the penetration of the cervix when using AI instruments is rather difficult. Furthermore, the seminal plasma of small ruminants affects the interaction with milk-based extenders and egg yolk which results in species-specific regimens for cooled liquid-preservation. Comparing all three species, the greatest pregnancy rates were obtained by AI with goat semen after cooled liquid-storage for several days.

In vitro embryo production (IVEP) in camelids: Present status and future perspectives

Camels are a fundamental livestock resource with a significant role in the agricultural economy of dry regions of Asia and Africa. Similarly, llamas and alpacas are an indigenous resource considered as beasts of burden in South America because of their surefootedness and ability to adapt. Camel racing, a highly lucrative and well-organized sport, camel beauty contests, and high demand for camel milk lead to a steady interest in the multiplication of elite animals by in vitro embryo production (IVEP) in this species during the last few decades. Although offspring have been produced from in vitro produced embryos, the technique is still not that well developed compared with other domestic animal species such as cattle. IVEP involves many steps, including the collection of oocytes from either slaughterhouse ovaries or live animals through ultrasound-guided transvaginal aspiration; in vitro maturation of these collected oocytes; collection and preparation of semen for fertilization; culture and passaging of cells for nuclear transfer, chemical activation of the reconstructed embryos, and in vitro culture of embryos up to the blastocyst stage for transfer into synchronized recipients to carry them to term. This review discusses the present status of all these steps involved in the IVEP of camelids and their future perspectives.

Saadeldin I, Ba-Awadh H, G. Al-Mutary M, F. Moumen A, N. Alowaimer A, Abdalla H. Efficiency of Commercial Egg Yolk-Free and Egg Yolk-Supplemented Tris-Based Extenders for Dromedary Camel Semen Cryopreservation

Simple Summary

This study compared the efficiency of commercial egg yolk-free (AndroMed, OPTIXcell) and egg yolk-supplemented (Triladyl, Steridyl) Tris-based extenders for semen cryopreservation in dromedary camels. The camel-specific extender SHOTOR was used for reference. SHOTOR, Triladyl, Steridyl, AndroMed, and OPTIXcell can all be used for camel semen cryopreservation; however, SHOTOR and Triladyl provide the best post-thawing sperm quality.

Abstract

This study compared the efficiency of commercial egg yolk-free (AndroMed, OPTIXcell) and egg yolk-supplemented (Triladyl, Steridyl) Tris-based extenders for semen cryopreservation in seven adult dromedary camels. The camel-specific extender SHOTOR was used as control. The collected semen samples were evaluated and diluted with SHOTOR, Triladyl, Steridyl, AndroMed, or OPTIXcell. The diluted semen was gradually cooled and equilibrated for two hours before liquid nitrogen freezing. Semen was evaluated prior to freezing and after freeze-thawing cycles for motility, kinetics, vitality, abnormality, plasma membrane integrity, and DNA fragmentation using computer-assisted sperm analysis. In pre-freezing evaluation, progressive sperm motility was higher in SHOTOR-diluted samples (21.54 ± 1.83) than in samples diluted with Steridyl, OPTIXcell, or AndroMed (15.76 ± 1.80, 17.43 ± 1.10, and 13.27 ± 1.07, respectively). Moreover, Triladyl and SHOTOR resulted in significantly (p < 0.05) better sperm vitality and DNA integrity than all other diluents, but Triladyl resulted in a significantly (p < 0.05) better plasma membrane integrity (87.77 ± 0.31) than SHOTOR (85.48 ± 0.58). In the post-thawing evaluation, Triladyl led to significantly (p < 0.05) higher sperm motility (38.63 ± 0.81%; p < 0.05) when compared to SHOTOR, Steridyl or AndroMed (35.09 ± 1.341%, 34.4 ± 0.84%, and 31.99 ± 1.48%, respectively), with OPTIXcell being the least efficient (28.39 ± 0.86%). Progressive sperm motility was the highest when using Triladyl. Post-thawing curvilinear, straight line and average path sperm velocities were highest with Triladyl and lowest with AndroMed. Triladyl led to the highest linearity coefficient and straightness sperm coefficient, while SHOTOR to the highest DNA and plasma membrane integrity. OPTIXcell and AndroMed resulted in poor post-thawing sperm vitality, while Steridyl was less efficient than Triladyl. The highest rate of sperm abnormalities was recorded with OPTIXcell and the lowest with SHOTOR or Triladyl. In conclusion, SHOTOR, Triladyl, Steridyl, AndroMed, and OPTIXcell can all be used for camel semen cryopreservation; however, SHOTOR and Triladyl provided the best post-thawing sperm quality. Based on our findings, Triladyl is the best commercially available extender for dromedary camel semen cryopreservation to date.

Optimization of sperm freezability in Bactrian camel using various dilution rates and equilibration times

The effect of different dilution rates and equilibration times on the cryopreservation of Bactrian camel spermatozoa was evaluated in the current study. Semen samples from four healthy adult males were collected, processed and pooled. They were then subjected to a completely randomized 4×2 factorial design including four dilution rates (DR; 1:1, 1:2, 1:4 or 1:8; v:v with SHOTOR diluent) and two equilibration times (ET; 1 or 2 h at 5ºC). After freezing and thawing, sperm kinematic parameters as well as viability, plasma membrane integrity, abnormality and seminal malondialdehyde level were assessed. According to the results, four-fold diluted samples recorded significantly higher values (P < 0.05) for sperm total (39.58 vs 31.83 and 33.33,%) and progressive motility (19.50 vs 14.00 and 14.25,%), viability (55.37 vs 43.50 and 48.75,%) and plasma membrane integrity (46.75 vs 37.25 and 37.37,%) than those of both less (1:1) and high (1:8) concentrated samples, respectively. By contrast, the percentage of abnormal spermatozoa and the concentration of seminal malondialdehyde were comparable among all treated groups. Moreover, ET revealed that 1 h equilibration had significantly higher sperm motility (37.04 vs 33.33%), linearity (42.29 vs 32.26%), beat cross-frequency (13.15 vs 8.70 Hz), plasma membrane integrity (42.25 vs 39.75%) and viability (51.37 vs 48.12%) compared with 2 h of ET (P < 0.05). Taken together, a four-fold dilution along with 1 h equilibration can be an optimal procedure to cryopreserve Bactrian camel sperm.

Ramifications of protease-based liquefaction of camel semen on physical, kinematic and surface glyco-pattern of cryopreserved spermatozoa

The efficiency of incorporating different proteases in the diluent for reducing camel semen viscosity, and subsequent ramifications on morpho-functional and glycan surface properties of cryopreserved spermatozoa were investigated. Ejaculates (n = 48) were collected from three adult camels, Camelus dromedarius, during the breeding season (January - March). A portion of each raw ejaculate was evaluated for sperm physical and morphological traits, whereas the other portion was divided into three aliquots assigned for the following liquefaction treatments: control (untreated), 0.1 mg/mL papain or 5 U/mL bromelain. All samples were diluted with Tris-lactose diluent containing the anti-enzyme E-64 to neutralize both proteases before being processed for cryopreservation. Post-thaw physical and kinematic properties of spermatozoa were analyzed using a computer-assisted sperm analysis (CASA) system. The sperm surface glycocalyx pattern was evaluated with a panel of 14 fluorescent lectins. Although bromelain was more effective in elimination of semen viscosity, there was a negative correlation between bromelain supplementation and values for the variables: normal sperm, intact acrosome and intact sperm cell membrane. Bromelain supplementation, compared to papain-treated and control samples, was positively correlated with secondary sperm abnormalities, increased straight-line velocity (VSL, μm/s) and straightness (%) of spermatozoa. Results from the glycan analysis indicated that both proteases did not affect the N-linked glycan content of the entire sperm surface, whereas the treatment with proteases induced little change in N-acetylgalactosamine and fucose terminating glycans in the tail region of the sperm. Functional studies are needed to evaluate the sperm fertility rates of bromelain- and papain-treated semen for application in camel assisted reproductive technologies.

The use of some assisted reproductive technologies in old world camelids

The use of camels for racing, milking and as show animals is growing in popularity, thus there is increased enthusiasm to breed more of the genetically superior animals. This review highlights recent developments in assisted reproductive techniques in camels, such as embryo transfer and artificial insemination, to ensure more rapid genetic progress. This paper discusses the difficulties involved in handling the semen due to its high viscosity and ways to reduce it. It also examines methods for short term liquid storage of fresh semen with and without the use of antioxidants to reduce oxidative stress. The widespread use of AI in camels is hindered by the lack of a reliable method for deep freezing and long term storage but various freezing protocols, cryoprotectants and freezing and thawing methods are discussed as well as different insemination techniques. Embryo transfer requires the donor to be superovulated and the recipients synchronized. This review discusses different protocols used for superovulation of donor animals and the problems involved. It also examines various methods to synchronize recipients, or how to make best use of non-synchronized or non ovulated recipients. Cryopreservation of embryos would greatly improve the wider use of ET and spread of genetics worldwide so methods for slow cooling and new methods of vitrification with promising results are discussed.

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.

Physical and kinematic properties of cryopreserved camel sperm after elimination of semen viscosity by different techniques

This investigation aimed to determine the influence of using different techniques for liquefaction of semen on post-thaw physical and dynamic characteristics of camel spermatozoa. A total of 144 ejaculates were collected from 3 adult camels, Camelus dromedarius, twice-weekly over 3 consecutive breeding seasons. A raw aliquot of each ejaculate was evaluated for physical and morphological properties, whereas the remaining portion was diluted (1:3) with glycerolated Tris lactose egg yolk extender, and was further subjected to one of the following liquefaction treatments: control (untreated), 5μl/ml α-amylase, 0.1mg/ml papain, 5u/ml bromelain, or 40-kHz nominal ultrasound frequency. The post-thaw objective assessment of cryopreserved spermatozoa, in all groups, was performed by a computer-assisted sperm analysis (CASA) system. The results revealed that all liquefaction treatments improved (P<0.05) post-thaw motility, viability and sperm motion criteria. However, an adverse effect (P<0.05) was observed in acrosome integrity, sperm cell membrane integrity and percent of normal sperm in all enzymatically-treated specimens compared to both control and ultrasound-treated semen. These results elucidate the efficiency of utilizing ultrasound technology for viscosity elimination of camel semen. In addition, developing enzymatic semen liquefaction techniques is imperious to benefit from when applying assisted reproductive technologies, particularly AI and IVF, in camels.

The influence of caffeine supplementation and concerted utilization of enzymatic and mechanical semen liquefaction on freezability of dromedary camel spermatozoa

Assisted reproductive technologies have been reported to improve reproductive efficiency and genetic potential in camelids. Two experiments were carried out to determine efficiency of centrifugation in the presence of a mucolytic agent for liquefaction of dromedary semen. In the first experiment, three groups, namely: I. Tris lactose (TL, control), II. Tris lactose supplemented with amylase (TL_A) and III. Tris lactose supplemented with amylase followed by seminal plasma removal via centrifugation (TL_A__Cent.) and re-suspension into enzyme free TL media. After equilibration, control group recorded 62.85 ± 4.28% motility and 1.3 ± 0.13 viscosity score, while TL_A group values were 72.88 ± 3.30% and 0.83 ± 0.07%, respectively. TL_A__Cent. group showed significant viscosity reduction (0.33 ± 0.05) and motility decline 47.85 ± 3.04% with increment in abnormalities and detached acrosome. The second experiment investigated the effect of caffeine addition to tolerate enzymatic and mechanical stress. Using 4 mM caffeine in amylase-treated semen (TL_AC) improved post-thaw motility 50.0 ± 1.29% and recovery rate 77.8 ± 3.83% compared to the control (40.17 ± 2.79% and 62.55 ± 8.39%), respectively. Caffeine supplemented centrifuged samples (TL_AC__Cent.) showed superiority (P < .05) in post-thaw motility and recovery rate (38.33 ± 6.41%, 62.76 ± 8.10%) compared to centrifuged samples TL_A__Cent. without caffeine addition (25.00 ± 2.88% and 40.47 ± 3.48%), respectively. Sperm kinetics showed that TL_A exhibited high (p < .05) values for mostly all sperm kinetics. Caffeine treatments showed superiority in velocity curved line (VCL, µm/s) 94.24 ± 8.44 for TL_AC and 104.25 ± 8.72 for the TL_AC__Cent. group compared to 86.8 ± 5.54 for TL_A, and 85.73 ± 5.99 for the TL_A__Cent. groups. In conclusion, preforming a combined enzymatic-mechanical protocol in the presence of an antioxidant may be crucial for refinement of camel semen cryopreservation.

Papain and its inhibitor E-64 reduce camelid semen viscosity without impairing sperm function and improve post-thaw motility rates

In camelids, the development of assisted reproductive technologies is impaired by the viscous nature of the semen. The protease papain has shown promise in reducing viscosity, although its effect on sperm integrity is unknown. The present study determined the optimal papain concentration and exposure time to reduce seminal plasma viscosity and investigated the effect of papain and its inhibitor E-64 on sperm function and cryopreservation in alpacas. Papain (0.1 mg mL–1, 20 min, 37°C) eliminated alpaca semen viscosity while maintaining sperm motility, viability, acrosome integrity and DNA integrity. Furthermore E-64 (10 µM at 37°C for 5 min after 20 min papain) inhibited the papain without impairing sperm function. Cryopreserved, papain-treated alpaca spermatozoa exhibited higher total motility rates after chilling and 0 and 1 h after thawing compared with control (untreated) samples. Papain treatment, followed by inhibition of papain with E-64, is effective in reducing alpaca seminal plasma viscosity without impairing sperm integrity and improves post-thaw motility rates of cryopreserved alpaca spermatozoa. The use of the combination of papain and E-64 to eliminate the viscous component of camelid semen may aid the development of assisted reproductive technologies in camelids.

Optimization of the cryopreservation of dromedary camel semen: Cryoprotectants and their concentration and equilibration times

Research into an optimal cryoprotectant, its concentration and equilibration time underlies the successful cryopreservation of dromedary camel spermatozoa. This study assessed the cryo-efficiency of different cryoprotectants, their concentration and equilibration time and any interactions. In experiment 1, semen samples (n = 4 males; 2 ejaculates/male) were frozen using Green Buffer containing one of four cryoprotectants (3% glycerol, ethylene glycol, methyl formamide, dimethyl sulfoxide) and using 4 equilibration times (10 min, 0.5, 1 and 2 h). Glycerol and ethylene glycol provided the best motility recovery rates and different equilibration times were not significant for any cryoprotectant nor were any interactions noted. However different equilibration times were pertinent for improved kinematic parameters BCF and VSL. In experiment 2, glycerol and ethylene glycol were evaluated at 4 concentrations (1.5, 3, 6, 9%) with 0.5 h equilibration (n = 4 males, 3 ejaculates/male). Sperm motility recoveries, kinematics and acrosome status were assessed. Higher values for LIN and STR were found with ethylene glycol. At 0 and 1 h post thaw 3 and 6% of either cryoprotectant resulted in better motility values than 1.5%. Acrosome integrity was compromised at 9% cryoprotectant. There were interactions between cryoprotectant and concentration in total motility at 0 and 1 h. For glycerol, total motility recoveries were best at 3-9%; for ethylene glycol 1.5-6% were best at 0 h and 3-6% at 1 h. In conclusion, 3-6% glycerol or ethylene glycol offered the best cryoprotection for camel sperm while different equilibration times were not critical.

Evaluation of cholesterol- treated dromedary camel sperm function by heterologous IVF and AI

Cholesterol (cholesterol-loaded cyclodextrins: CLC) treatment of dromedary camel sperm prior to freezing enhances cryosurvival. The present study first validated the efficacy of a heterologous zona-free goat oocyte assay (n=115 oocytes) to evaluate camel sperm function in vitro (Experiment 1: n=6 bulls), then examined the effects of CLC treatment (1.5mg/mL CLC; CLC+) versus no treatment (0 CLC) of fresh (Experiment 2: n=4 bulls) and frozen-thawed (Experiment 3: n=5 bulls) camel sperm to penetrate, de-condense and form pro-nuclei in in vitro-matured goat oocytes. Finally, the ability of fresh 0 CLC and CLC+ sperm to fertilize in vivo was studied by artificially inseminating super-ovulated females (n=7-9 per treatment) and examining embryo production (Experiment 4: n=4-5 bulls/treatment). Camel spermatozoa penetrated (60%) and formed pro-nuclei (33%) in goat oocytes demonstrating the utility of this heterologous system for assessing sperm function in vitro. For fresh spermatozoa, 0 CLC-treated sperm performed better than their CLC+ counterparts for all parameters measured (P<0.05). In contrast, cryopreservation resulted in a sharp decline in sperm-oocyte interaction in 0 CLC aliquots but remained unaltered in CLC+ aliquots demonstrating a protective effect of cholesterol treatment. There was no difference between treatments in the in vitro fertilizing ability of frozen-thawed sperm or in the numbers of embryos retrieved following AI with fresh 0 CLC or CLC+ sperm. We conclude that although CLC treatment of dromedary camel sperm improves sperm motility it fails to confer an advantage to them in terms of improved in vitro sperm-oocyte interaction or in vivo fertilization under the conditions tested.

Effect of α-Amylase, Papain, and Spermfluid treatments on viscosity and semen parameters of dromedary camel ejaculates

Ejaculates from five clinically healthy dromedary camels (Camelus dromedarius) were used to evaluate the effects of different enzymatic treatments (Amylase, Papain, Spermfluid) on liquefaction and seminal parameters. After collection, ejaculates were divided into 5 aliquots: (1) kept undiluted (control); or diluted 1:1 with: (2) Tris-Citrate-Fructose (TCF), (3) TCF containing Amylase, (4) TCF containing Papain or (5) Spermfluid containing Bromelain. At 120 min after dilution, each aliquot was evaluated, at 20-min intervals, for viscosity, motility, viability and agglutination. Only the aliquots diluted with TCF containing Papain underwent complete liquefaction. Sperm motility decreased significantly during the observation times, except for the samples diluted with Spermfluid (P=0.005). Diluted samples showed different levels of agglutination, with the lowest being observed in the control and the highest in the Papain-treated samples. The viscosity of dromedary camel ejaculates could be effectively reduced by using the proteolytic enzyme Papain.

Effects of varying doses of β-nerve growth factor on the timing of ovulation, plasma progesterone concentration and corpus luteum size in female alpacas (Vicugna pacos)

Ovulation in camelids is induced by the seminal plasma protein ovulation-inducing factor (OIF), recently identified as β-nerve growth factor (β-NGF). The present study measured the total protein concentration in alpaca seminal plasma using a bicinchoninic acid (BCA) protein quantification assay and found it to be 22.2 ± 2.0 mg mL–1. To measure the effects of varying doses of β-NGF on the incidence and timing of ovulation, corpus luteum (CL) size and plasma progesterone concentration, 24 female alpacas were synchronised and treated with either: (1) 1 mL 0.9% saline (n = 5); (2) 4 µg buserelin (n = 5); (3) 1 mg β-NGF protein (n = 5); (4) 0.1 mg β-NGF (n = 5); or (5) 0.01 mg β-NGF (n = 4). Females were examined by transrectal ultrasonography at 1–2-h intervals between 20 and 45 h after treatment or until ovulation occurred, as well as on Day 8 to observe the size of the CL, at which time blood was collected to measure plasma progesterone concentrations. Ovulation was detected in 0/5, 5/5, 5/5, 3/5 and 0/4 female alpacas treated with saline, buserelin, 1, 0.1 and 0.01 mg β-NGF, respectively. Mean ovulation interval (P = 0.76), CL diameter (P = 0.96) and plasma progesterone concentration (P = 0.96) did not differ between treatments. Mean ovulation interval overall was 26.2 ± 1.0 h. In conclusion, buserelin and 1 mg β-NGF are equally effective at inducing ovulation in female alpacas, but at doses ≤0.1 mg, β-NGF is not a reliable method for the induction of ovulation.

Artificial insemination in dromedary camels

Artificial insemination (AI) is an important technique in all domestic species to ensure rapid genetic progress. The use of AI has been reported in camelids although insemination trials are rare. This could be because of the difficulties involved in collecting as well as handling the semen due to the gelatinous nature of the seminal plasma. In addition, as all camelids are induced ovulators, the females need to be induced to ovulate before being inseminated. This paper discusses the different methods for collection of camel semen and describes how the semen concentration and morphology are analyzed. It also examines the use of different buffers for liquid storage of fresh and chilled semen, the ideal number of live sperm to inseminate and whether pregnancy rates are improved if the animal is inseminated at the tip of the uterine horn verses in the uterine body. Various methods to induce ovulation in the female camels are also described as well as the timing of insemination in relation to ovulation. Results show that collection of semen is best achieved using an artificial vagina, and the highest pregnancy rates are obtained if a minimum of 150×10(6) live spermatozoa (diluted in Green Buffer, lactose (11%), or I.N.R.A. 96) are inseminated into the body of the uterus 24h after the GnRH injection, given to the female camel to induce ovulation. Deep freezing of camel semen is proving to be a great challenge but the use of various freezing protocols, different diluents and different packaging methods (straws verses pellets) will be discussed. Preliminary results indicate that Green and Clear Buffer for Camel Semen is the best diluent to use for freezing dromedary semen and that freezing in pellets rather than straws result in higher post-thaw motility. Preservation of semen by deep-freezing is very important in camelids as it prevents the need to transport animals between farms and it extends the reproductive life span of the male, therefore further work needs to be carried out to improve the fertility of frozen/thawed camel spermatozoa.

Interspecies embryo transfer in camelids: the birth of the first Bactrian camel calves (Camelus bactrianus) from dromedary camels (Camelus dromedarius)

Interspecies embryo transfer is a possible approach that can be used to conserve endangered species. It could provide a useful technique to preserve the Iranian and wild Bactrian camels, both of which are threatened with extinction. In the present study, one Bactrian camel was superovulated using decreasing doses of FSH (60, 40, 30, 30, 20, 20 mg, b.i.d.; Folltropin-V; Bioniche, London, ON, Canada) for 6 days, followed by a single injection of FSH (20 mg, i.m.) on Day 7. Daily ovarian ultrasonography was performed until most of the growing follicles had reached a mature size of 13-17 mm, at which time the camel was mated twice, 24 h apart, with a fertile male Bactrian camel. At the time of first mating, female camels were given 20 microg, i.v., buserelin (Receptal; Intervet, Boxmeer, The Netherlands). One day after the donor camel had been mated, the dromedary recipients (n = 8) were injected with 25 mg, i.v., porcine LH (Lutropin-V; Bioniche) to induce ovulation. Embryos were recovered on Day 8.5 after the first mating and transferred non-surgically into recipients on Day 7.5 after LH injection. Pregnancy was diagnosed 25 days after embryo transfer. Healthy Bactrian camel calves (n = 4) were born without any particular complications at the time of parturition (e.g. dystocia and neonatal diseases). The present study is the first report of the birth of Bactrian camel calves from dromedary camels, as well as the first report of interspecies embryo transfer in old world camelids.