The annual reproductive cycle of the male snow leopard (Panthera uncia) was characterized by evaluating seminal and endocrine traits monthly. Testicular volume was greatest (P < 0.05) during the winter months when the quality of ejaculate was optimal. Ejaculate volume, total sperm concentration ml⁻¹, motile sperm concentration per ejaculate, sperm morphology and sperm motility index were lowest during the summer and autumn months compared with the winter and spring. Peripheral LH, FSH and testosterone concentrations were also lowest during the summer months, increasing during the autumn just before the increase in semen quality, and were maximal during the winter months. There was a direct relationship (P < 0.01) between: (1) testosterone and testicular volume, total sperm concentration ml⁻¹, motile sperm concentration per ejaculate and ejaculate volume, and (2) LH and testicular volume and motile sperm concentration per ejaculate. In summary, although spermatozoa were recovered throughout the year, optimal gamete quality was observed during the winter and spring. Although previous studies in felids have demonstrated seasonal effects on either seminal or endocrine traits, this is the first study to demonstrate a distinct effect of season on both pituitary and testicular function.

Summary. Frequent blood samples were collected to study hormonal responses to GnRH in male and female leopards and tigers. Animals were anaesthetized with ketamine–HCl and blood samples were collected every 5 min for 15 min before and 160 min after i.v. administration of GnRH (1 μg/kg body weight) or saline. No differences in serum cortisol concentrations were observed between sexes within species, but mean cortisol was 2-fold greater in leopards than tigers. GnRH induced a rapid rise in LH in all animals (18·3 ± 0·9 min to peak). Net LH peak height above pretreatment levels was 3-fold greater in males than conspecific females and was also greater in tigers than leopards. Serum FSH increased after GnRH, although the magnitude of response was less than that observed for LH. Basal LH and FSH and GnRH-stimulated FSH concentrations were not influenced by sex or species. Serum testosterone increased within 30–40 min after GnRH in 3/3 leopard and 1/3 tiger males. Basal testosterone was 3-fold greater in tiger than leopard males. LH pulses (1–2 pulses/3 h) were detected in 60% of saline-treated animals, suggesting pulsatile gonadotrophin secretion; however, in males concomitant testosterone pulses were not observed. These results indicate that there are marked sex and species differences in basal and GnRH-stimulated hormonal responses between felids of the genus Panthera which may be related to differences in adrenal activity.

Keywords: GnRH, leopard, tiger, LH, cortisol, testosterone

The ovarian response to equine chorionic gonadotrophin (eCG) and human chorionic gonadotrophin (hCG), the effect of timing of ovulation relative to hCG injection and the use of laparoscopic intrauterine artificial insemination (AI) were examined in two subspecies of tiger (Panthera tigris). Adult female tigers were subjected to the same eCG/hCG treatment followed by laparoscopy under xylazine/diazapam/ketamine HCl anaesthesia at 39–42 h (Group I, n = 9), 46–49 h (Group II, n = 5) or 51–55 h (Group III, n = 5) after hCG. Six of these females, observed to be postovulatory at the time of laparoscopy (Group II, n = 3; Group III, n = 3), were subjected to intrauterine AI. The number of preovulatory follicles observed on the ovaries of Group I females was twofold greater (P < 0.05) than the number observed on ovaries of females in Group II and III. Fewer (P < 0.05) corpora lutea were observed on ovaries of Group I females (1.3 ± 0.6) compared with the number of corpora lutea in Group II and III (combined average, 7.8 ± 0.8 corpora lutea per female). Only one of ten females in Groups II and III failed to ovulate by the time of laparoscopy. Four Group I females never ovulated, based on a laparoscopic re-evaluation 4 weeks later. One female inseminated 46 h after hCG (Group II) became pregnant and delivered a healthy cub after a normal gestation. There were no apparent differences between subspecies in response to the same ovulation induction protocol. Results demonstrate the importance of the relationship between exogenous gonadotrophin treatment and onset of anaesthesia for laparoscopic examination and AI in tigers. Data clearly indicate that anaesthesia/laparoscopy conducted too early (39–42 h after hCG) compromises the number of females and proportion of follicles ovulating. In contrast, ovulation success is high if anaesthesia/laparoscopy is performed after this time, and intrauterine insemination can result in healthy young.

Summary. Oestrous cycles of goats were synchronized hormonally. Immunoreactive oxytocin was undetectable (< 0·1 ng/mg protein) in media from granulosa cells isolated before the LH surge for small (1–2 mm), medium (3–5 mm) and large >5 mm diameter) follicles when cultured for 24 h without or with added hormones. Granulosa cells from large and medium, but not small, follicles isolated 6–12 h after spontaneous preovulatory LH surges secreted high concentrations of oxytocin (4–12 ng/mg protein). Addition of PGE-2 (1 μg/ml) caused a further significant (P < 0·05) increase in oxytocin secretion by cultured granulosa cells, whereas PGF-2α, FSH and LH were ineffective when added to culture media.

Ovarian venous blood and granulosa cells were collected at 0, 6, 12 or 18 h after GnRH injection in hormonally synchronized goats. Peripheral serum LH values were increased significantly in all but 2 of 22 goats within 2 h of GnRH injection. At the earliest sampling time after GnRH (6 h), ovarian venous levels of oxytocin were increased significantly from basal levels of 0·4 pg/ml to 2·4 pg/ml. Oxytocin concentrations in follicular fluid increased from a basal value of 67 pg/ml to 155 pg/ml by 6 h and to 372 pg/ml by 18 h after GnRH injection. Oxytocin secretion by cultured granulosa cells was not increased significantly by 6 h (0·1 ng/mg protein) but rose to 1·4 and 3·5 ng/mg protein at 12 and 18 h, respectively. Approximately parallel increases occurred in progesterone in ovarian venous blood and granulosa cell culture media over the same time period. Oestradiol secretion by granulosa cells cultured with androstenedione as an aromatizable substrate was essentially unchanged when obtained from 0 to 12 h after GnRH injection (31–37 ng/mg protein), but fell significantly to 7·4 ng/mg in cells obtained 18 h after GnRH injection, indicative of decreasing aromatase activity as luteinization progresses during the preovulatory period. It is concluded that granulosa cells, in response to the preovulatory LH surge, acquire the ability to synthesize and secrete oxytocin in parallel with the increased progesterone and decreased oestradiol secretion which occurs during luteinization.

Keywords: oxytocin; granulosa cells; goat; LH; luteinization

Summary. Electroejaculates from tigers were collected and half was used fresh to inseminate tiger eggs in vitro and domestic cat eggs stored in a hypertonic salt solution. The remainder was pelleted, frozen in a solution of 20% egg yolk, 11% lactose and 4% glycerol, thawed and cultured with tiger and domestic cat eggs. The motility index ((sperm % motility) + (status rating × 20))/2 for thawed spermatozoa was about 86% of that in fresh aliquots. Of the 49 tiger oocytes inseminated in vitro with fresh spermatozoa, 34 (69·4%) cleaved, compared with 33 of 47 oocytes (70·2%) cultured with thawed spermatozoa (P > 0·05). Embryos generated by either sperm treatment could develop in vitro to the 16-cell or morula stage. Fresh and thawed tiger spermatozoa were equally capable (P > 0·05) of binding and penetrating the outer and inner zona pellucida of domestic cat eggs. These results demonstrate the ability of frozen–thawed tiger spermatozoa to (i) penetrate homologous and heterologous eggs and (ii) result in conspecific, advanced development of preimplantation embryos in vitro.

Keywords: tiger; spermatozoa; cryopreservation; in vitro fertilization; embryo

Obesity is associated with a diverse set of metabolic disorders, and has reproductive consequences that are complex and not well understood. The adipose tissue-produced leptin has dominated the literature with regards to female fertility complications, but it is pertinent to explore the likely role of other adipokines – adiponectin and resistin – as our understanding of their biological functions emerge. Leptin influences the developing embryo, the functioning of the ovary and the endometrium, interacts with the release and activity of gonadotrophins and the hormones that control their synthesis. In this review such biological actions and potential roles of the adipokines leptin, adiponectin and resistin are explored in relation to female fertility and the complexity of the obese metabolic state.

Immune cells and their cytokine products have powerful local effects within body tissues. There has been great interest in the potential role of these cells, not only during destruction of the corpus luteum but also during its functional lifespan. In this study, lymphocytes, macrophages and major histocompatibility complex class II molecules were quantified using immunohistochemistry and the reverse transcription–polymerase chain reaction was used to detect mRNA for tumour necrosis factor α and interferon γ within corpora lutea from three groups of cows: (1) corpora lutea collected at an abattoir and assessed visually into four stages (stage I (days 1–5), stage II (days 6–12), stage III (days 13–18) and stage IV (days 19–21) of the oestrous cycle); (2) corpora lutea collected around natural luteolysis (days 14–20); and (3) corpora lutea collected 6, 12 and 24 h after prostaglandin F_2α-induced luteolysis. The numbers of T lymphocytes (CD5+ and CD8⁺) were significantly higher (P < 0.05) at stage IV and from day 16 onwards, before functional luteolysis. There were significantly higher numbers (P < 0.01) of macrophages at stages I, III and IV compared with stage II in visually staged tissue. Major histocompatibility complex class II molecules were increased (P < 0.05) at stages I and IV compared to stage II and at all times after induced luteolysis. Using reverse transcription–polymerase chain reaction, mRNA encoding tumour necrosis factor α and interferon γ was detected in all luteal tissue collected around natural luteolysis and after induced luteolysis. These findings, particularly the increase in T lymphocytes before functional luteolysis, provide further evidence of a significant role for the immune system in affecting reproductive function in cows.