Reproductive Physiology and Development of Artificial Insemination Technology in Killer Whales (Orcinus orca)1

Semen collection, characterisation and artificial insemination in the beluga (Delphinapterus leucas) using liquid-stored spermatozoa

Ejaculates were collected from a beluga (Delphinapterus leucas) to gain an understanding of sperm biology and develop a short-term sperm preservation method for use in artificial insemination (AI). Ejaculate parameters and biochemistry, semen production and serum testosterone concentrations of an adult male were characterised for 21 months. Sperm viability, acrosome integrity and morphology did not change (P > 0.05) but ejaculate volume, sperm concentration and total spermatozoa per ejaculate were higher (P < 0.05) from January to June than from July to December. Peak testosterone concentrations (P < 0.05) were observed from October to April (8.0 ± 1.6 ng mL–1). The effects of hyaluronic acid (HA), antioxidants, storage temperature and time on in vitro sperm characteristics were examined. Motility parameters and viability were improved (P < 0.05) when semen was stored at 5°C compared with 21°C. During the first 24 h of storage sperm agglutination was absent only at 5°C in the presence of HA. A nulliparous 28-year-old female was inseminated endoscopically with liquid-stored semen. A pregnancy and birth of a calf was achieved following AI for the first time in this species, thereby validating both the AI technique and the fertility of beluga spermatozoa after chilled storage in a specialised diluent.

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.

Characterization of male killer whale (Orcinus orca) sexual maturation and reproductive seasonality

Longitudinal serum testosterone concentrations (n=10 males) and semen production (n=2 males) in killer whales were evaluated to: (1) characterize fluctuations in serum testosterone concentrations with respect to reproductive maturity and season; (2) compare morphologic changes to estimated age of sexual maturity, based on changes in serum testosterone concentrations; and (3) evaluate seasonal changes in sperm production. Classification of reproductive status and age class was based on differences (P < 0.05) in serum testosterone concentrations according to age; juvenile males ranged from 1 to 7 years (mean+/-S.D. testosterone, 0.13+/-0.20 ng/mL), pubertal males from 8 to 12 years (2.88+/-3.20 ng/mL), and sexually mature animals were 13 years and older (5.57+/-2.90 ng/mL). For captive-born males, serum testosterone concentrations, total body length and height to width ratio of the dorsal fin were 0.7+/-0.7 ng/mL, 495.6+/-17.5 cm and 1.14+/-0.13c m, respectively, at puberty; at sexual maturity, these end points were 6.0+/-3.3 ng/mL, 548+/-20 cm and 1.36+/-0.1cm. Serum testosterone concentrations were higher (P<0.05) from March to June than from December to February in pubertal animals (4.2+/-3.4 ng/mL versus 1.4+/-2.6 ng/mL) and than from September to December in sexually mature animals (7.2+/-3.3 ng/mL versus 4.0+/-2.0 ng/mL). Ejaculates (n = 90) collected from two males had similar (P > 0.05) sperm concentrations across all months. These data represent the first comprehensive study on male testosterone concentrations during and after sexual maturation, and on reproductive seasonality in the killer whale.

Development of sperm sexing and associated assisted reproductive technology for sex preselection of captive bottlenose dolphins (Tursiops truncatus)

Research was conducted to develop sperm sorting and novel sperm preservation methodologies for sex predetermination in the bottlenose dolphin (Tursiops truncatus) using artificial insemination. In Study 1, the effect of seminal plasma (SP), sperm concentration and freezing rate (FR) on in vitro sperm quality of liquid-stored, non-sorted spermatozoa was examined. There was no effect (P > 0.05) of prefreeze SP addition on post-thaw quality (progressive motility, kinetic rating, sperm motility index (SMI), viability and acrosome integrity). Post-thaw motility parameters and viability were higher (P < 0.05) for slow FR than fast FR samples. In Study 2 investigating the effects of liquid storage and sorting on sperm quality, motility and SMI after sorting and centrifugation were lower (P < 0.05) than those of the initial ejaculate. The sort rate for enrichment (91 ± 4% purity) of X- and Y-bearing spermatozoa was 3400 ± 850 spermatozoa sex−1 s−1. In Study 3, compared with a modified straw method, directional freezing resulted in enhanced in vitro quality of sorted and non-sorted spermatozoa derived from liquid-stored semen (P < 0.05). In Study 4, endoscopic insemination of three dolphins with sorted, frozen–thawed X-bearing spermatozoa resulted in one conception and the birth of a female calf. High-purity sorting of dolphin spermatozoa, derived from liquid-stored semen, can be achieved with minimal loss of in vitro sperm quality and samples are functional in vivo.

Effects of Bovine Serum Albumin and Trehalose in Semen Diluents for Improvement of Frozen-Thawed Ram Spermatozoa

In this study, two following experiments were performed to improve post-thaw motility and viability of frozen-thawed ram spermatozoa. We examined i) the effects of different concentrations of bovine serum albumin (0, 0.3, 1, 5, 10 and 15% BSA) in semen diluents lacking egg yolk and ii) the effects of four semen diluents, fructose (F: control) and trehalose (T) in semen diluents containing egg yolk, 15% BSA in semen diluents without egg yolk (BSA), and modified phosphate buffered saline (m-PBS). Frozen-thawed spermatozoa were examined for progressive sperm motility, viability, morphological abnormality, sperm tail swelling test, and sperm acrosome integrity. In Experiment 1, the rates of sperm motility immediately after thawing (0 h) were significantly (P<0.05) higher in the 10 and 15% BSA groups (55.0 +/- 2.9 and 58.3 +/- 6.7%, respectively) than in the positive control (F) group (41.7 +/- 4.4%). The rate of sperm viability in the negative control (0% BSA) group (80.2 +/- 3.3%) was significantly (P<0.05) lower than in the positive control (F) group (89.8 +/- 1.5%), but when compared with the F group, no significant differences were found among the 0.3, 1, 5, 10 and 15% BSA groups at 0 h. The rates of sperm morphological abnormality of the 10 and 15% BSA groups (6.5 +/- 1.3 and 6.3 +/- 1.1%, respectively) were significantly (P<0.05) lower at 0 h than that in the 1% BSA group (16.3 +/- 5.2%). In Experiment 2, T addition improved (P<0.05) the post-thaw motility compared with the F and BSA groups. Furthermore, at 3 and 6 h, the post-thaw motility of the T group (36.3 +/- 2.4 and 25.0 +/- 2.0%, respectively) was significantly (P<0.05) higher than in the BSA (26.3 +/- 2.4 and 18.8 +/- 1.3%, respectively) and F (28.8 +/- 3.8 and 18.8 +/- 2.4%, respectively) groups. The post-thaw sperm motility and viability in the m-PBS group were significantly (P<0.05) lower than those of the control (F), T, and BSA groups throughout all observation points. These results indicate that 10 and 15% BSA can be substituted for egg-yolk for ram semen diluent and that the addition of trehalose enhances motility and viability of ram spermatozoa after freezing and thawing.

Estrous cycle characterisation and artificial insemination using frozen–thawed spermatozoa in the bottlenose dolphin (Tursiops truncatus)

The reproductive endocrinology of the bottlenose dolphin,Tursiops truncatus,was characterized to facilitate the development of artificial insemination using cryopreserved spermatozoa. Specific objectives were: (i) to determine the excretory dynamics of urinary luteinizing hormone (LH) and ovarian steroid metabolites during the estrous cycle; (ii) to evaluate the effect of an exogenously administered synthetic progesterone analog (altrenogest) on reproductive hormone excretion; (iii) to correlate follicular growth and ovulation (as determined by transabdominal ultrasound) to urinary LH and ovarian steroid metabolites; (iv) examine thein vivofertilisation capacity of cryopreserved semen, and (v) to develop an intrauterine insemination technique. Based on urinary endocrine monitoring of natural estrous cycles (2 consecutive cycles) and nine post altrenogest cycles in ten females, estrous cycles were found to be 36 days long and comprised of an 8 day and 19 day follicular and luteal phase, respectively. Peak estrogen conjugates (EC; 5.4 ± 3.8 ng/mg creatinine (Cr)) occurred 8 h prior to the LH surge (70.9 ± 115.7 ng/mg Cr). The time of ovulation, as determined by ultrasonography, occurred 32.1 ± 8.9 h and 24.3 ± 7.0 h after the onset of the LH surge and LH peak, respectively. Mean preovulatory follicular diameter and circumference were 2.1 ± 0.5 cm and 6.5 ± 1.5 cm, respectively. Of the 27 estrous synchronisation attempts, 13 resulted in an ovulatory cycle, with ovulation occurring 21 days post-altrenogest treatment. Intrauterine (4 of 5) and intracornual (1 of 3) inseminations conducted across eight estrous cycles resulted in five pregnancies (63%), one pregnancy resulted from the use of liquid stored semen, whereas four were achieved using cryopreserved semen. These data provide new information on female bottlenose dolphin reproductive physiology, and demonstrate that the combination of endocrine monitoring and serial ultrasonography contributed to successful AI using liquid-stored and cryopreserved semen.