Predictive characteristics of male fertility in alpacas with special reference to seminal NGF

Recent studies document the LH-releasing pathway of nerve growth factor (NGF) in male camelids and that the LH response to seminal NGF is associated with elevated plasma testosterone concentration. Results provide rationale for the hypothesis that NGF in semen is associated with male fertility. In Experiment 1, the association between the amount of NGF in the ejaculate and characteristics of the male reproductive system was examined in alpacas. The concentration of NGF was measured by radioimmunoassay in semen samples collected from male alpacas (n = 47) and correlated with sperm morphology and motility, and measurements of the male reproductive anatomy. Most ejaculates had NGF concentrations that, based on previous studies, triggered ovulation in female camelids, however, we only found a positive correlation between NGF concentration with sperm concentration, thread formation and total NGF, and a negative correlation with pH. In Experiment 2, a retrospective analysis was carried out to determine if breeding performance during the previous season was related to recent concentrations of seminal NGF in male alpacas (n = 22). Birth rates tended to be correlated with sperm concentration and total amount of NGF in the ejaculate (P = 0.09). Experiment 3 was a prospective study to determine the relationship between seminal NGF (n = 8 male alpacas) and ovulation and pregnancy rates in a breeding trial. No association was detected between seminal NGF concentration and ovulation rate, pregnancy rate, or LH response in the female. We conclude that among the breeding males used in our study, the abundance of seminal NGF was correlated with sperm concentration and thread formation, however, it was not predictive of male fertility in alpacas. Examination of males not previously selected as breeding stock may be expected to include a broader range of seminal NGF and provide a more comprehensive understanding of the relationship between seminal NGF and male fertility.

Development and Biodistribution of a Nerve Growth Factor Radioactive Conjugate for PET Imaging

PURPOSE

The purpose of these studies was to develop a nerve growth factor (NGF) radiometal-chelator conjugate to determine the biodistribution and brain uptake of NGF by positron emission tomography/computerized tomography (PET-CT).

PROCEDURES

Purified NGF from llama seminal plasma was conjugated with FITC, and the chelator NOTA or DFO. NGF conjugates were evaluated for bioactivity. NOTA- and DFO-conjugated NGF were radiolabeled with gallium-68 or zirconium-89 ([68 Ga]GaCl3, half-life = 68 min; [89Zr]Zr(oxalate)4, half-life = 3.3 days). [89Zr]Zr-NGF was evaluated for biodistribution (0.5, 1, or 24 h), PET imaging (60 min), and brain autoradiography in mice.

RESULTS

Cell-based in vitro assays confirmed that the NGF conjugates maintained NGF receptor-binding and biological activity. Zirconium-89 and gallium-68 radiolabeling showed a high efficiency; however, only[89Zr]Zr-NGF was stable in vitro. Biodistribution studies showed that, as with most small proteins < 70 kDa, [89Zr]Zr-NGF uptake was predominantly in the kidney and was cleared rapidly with almost complete elimination of NGF at 24 h. Dynamic PET imaging from 0-60 min showed a similar pattern to ex vivo biodistribution with some transient liver uptake. Interestingly, although absolute brain uptake was very low, at 24 h after treatment, cerebral cortex uptake was higher than any other brain area examined and blood.

CONCLUSIONS

We conclude that conjugation of DFO to NGF through a thiourea linkage allows effective radiolabeling with zirconium-89 while maintaining NGF bioactivity. Following intravenous administration, the radiolabeled NGF targets non-neuronal tissues (e.g., kidney, liver), and although absolute brain uptake was very low, the brain uptake that was observed was restricted to the cortex.

Predictors of the ovarian superstimulatory response and oocyte collection in prepubertal heifers

The objectives were to investigate the relationships between antral follicle counts and plasma AMH and FSH at the time of follicular wave emergence in prepubertal calves, and to determine the effects of age and duration of gonadotropin treatment on the ovarian superstimulatory response in pre- and post-pubertal heifers. Hereford crossbred prepubertal (Replicate 1 and 2, n = 20) and post-pubertal heifers (Replicates 1, n = 8; Replicate 2, n = 8) were assigned randomly to 2 treatment groups and given FSH for either 4 or 7 d (25 mg pFSH im at 12-h intervals). Prepubertal heifers were first treated at 4 mo and again at 7 mo of age. Blood samples were collected immediately before the first FSH administration, that was initiated 36 h after follicular ablation. An LH treatment (12.5 mg im) was given 12 h after the last FSH injection. Follicular fluid and cumulus-oocyte complexes (COC) were collected 24 h after LH treatment. At wave emergence, the number of follicles ≥1 mm (AFC, 31.1 ± 4.0 vs 16.2 ± 1.8; P < 0.001) and the plasma concentrations of AMH (606.4 ± 90.5 vs 279.6 ± 28.3 pg/mL; P = 0.001) were higher at 4 than at 7 mo of age, while plasma FSH concentrations did not differ between ages. At oocyte collection, a higher number of follicles ≥6 mm were observed in prepubertal calves at 4 mo of age and post-pubertal heifers than in calves at 7 mo of age (32.4 ± 5.4 and 22.0 ± 2.3 vs 14.9 ± 2.0, respectively; P = 0.003). Intrafollicular concentrations of estradiol were lower (23.7 ± 4.5 vs 144.0 ± 29.5 ng/mL; P < 0.0001) and of progesterone tended to be higher (217.5 ± 29.3 vs 157.0 ± 33.9 ng/mL; P = 0.07) in the 7- than in the 4-d groups. A greater number of COC was collected from calves at 4 mo of age and heifers than the 7-mo-old calves (13.4 ± 2.6 and 6.0 ± 1.0 vs 5.8 ± 1.1, respectively; P = 0.008). Overall, the 7-d FSH treatment tended to result in a greater proportion of expanded COC than the 4-d treatment in calves (50.1 ± 7.7 vs 31.9 ± 6.8%; P = 0.07). In summary, there was a positive relationship between AFC and plasma AMH concentrations at the time of wave emergence. A higher AFC was observed in calves at 4- than 7-mo of age, which resulted in greater ovarian response to gonadotropin treatment. Following an exogenous LH stimulus, COC maturation rates were greater in the 7-d than in the 4-d FSH treatment groups, resulting in collection of a higher proportion of fully expanded COC.

118 A comparison of intravaginal progesterone devices for fixed-time artificial insemination in beef cattle

Intravaginal progesterone (P4) devices used for ovarian synchronization before fixed-time AI (FTAI) differ in drug release, which may influence fertility outcome. A 2×2 study was designed to determine the effects of different intravaginal devices (PRID Delta, 1.55g of P4 vs. CIDR, 1.38g of P4) and parity (heifers vs. cows) on follicular dynamics, expression of oestrus, and pregnancy per AI (P/AI). At random stages of the oestrous cycle, nulliparous beef heifers and lactating cows were given 100µg of gonadorelin (gonadotrophin-releasing hormone, GnRH) intramuscularly (IM) and assigned randomly to either the PRID (n=76 heifers, 76 multiparous, 27 primiparous) or CIDR (n=76 heifers, 73 multiparous, 32 primiparous) group. Devices were removed 5 days later, an oestrus-detection patch was applied just cranial to the tail head, and 500µg of cloprostenol was given IM at the time of device removal and again 24h later. At 72h after device removal, cattle were inseminated and given 100µg of GnRH IM. Transrectal ultrasonography was used to determine the diameter of the largest follicle on the day of device removal and at FTAI, ovulation time, and pregnancy status 30 days after FTAI. A colour change of ≥50% of the oestrus-detection patch at FTAI was taken as expression of oestrus. Data were compared among groups by 2-way ANOVA using MIXED and GLIMMIX procedures. There were no interactions between P4 device and parity for any endpoint. The diameter of the largest follicle (mean±s.e.m.) was not different between PRID and CIDR groups on either the day of device removal (10.6±0.1 vs. 10.9±0.1mm) or the day of FTAI (13.7±0.1 vs. 13.9±0.1mm). The proportion displaying oestrus did not differ between P4 device groups, but was greater in heifers than in cows [121/152 (79.6%) vs. 135/207 (65.2%); P&lt;0.01], and the interval from FTAI to ovulation was shorter in heifers than in cows (27.8±1.2 vs. 32.0±1.1 h; P=0.01). The P/AI was not different between P4 device groups or parity groups (overall 67.0%, 238/355). However, among lactating cows, the P/AI tended to be greater in the PRID vs. CIDR group [75/102 (73.5%) vs. 64/105 (61.0%); P=0.10], and was greater in multiparous vs. primiparous cows [106/148 (71.6%) vs. 33/59 (55.9%); P=0.04]. Among cattle that displayed oestrus, the P/AI tended to be greater in the PRID vs. CIDR group [92/123 (74.8%) vs. 85/131 (64.9%); P=0.09]. Among lactating cows that displayed oestrus, the P/AI was greater in multiparous vs. primiparous cows [74/94 (78.2%) vs. 24/42 (57.1%); P&lt;0.01]. In summary, follicular dynamics and expression of oestrus did not differ between PRID and CIDR groups, but the P/AI tended to be greater in PRID-treated lactating cows and in cattle that displayed oestrus. This research was supported by CEVA Animal Health, Saskatchewan ADF, Agriculture and Agri-Foods Canada, and Rockway Inc.

27 Cryopreservation of bovine semen using cell-permeating antioxidant and protein-free extender

Effective semen extenders are those with defined composition that promote sperm longevity. Generation of reactive oxygen species during semen cryopreservation results in sperm membrane lipid peroxidation and reduced longevity. Recent studies demonstrated that small cell permeating dimethyl tyrosine conjugated peptides, such as SS-31, translocate to the mitochondria and scavenge excess reactive oxygen species. The present study was conducted to test the hypothesis that the addition of SS-31 improves the post-thaw quality and fertility potential of bovine semen. The effect of SS-31 was tested in combination with two extenders: (1) conventional tris-egg yolk-glycerol (TEYG, control) and (2) cholesterol-cyclodextrin+tris-glycerol (CC+TG, a defined protein-free extender). Fifteen ejaculates were collected from 5 Black Angus bulls. Ejaculates were diluted to 400×106 spermmL−1 with tris-citric acid buffer, and treated with 0, 50, or 100 µmolmL−1 SS-31 for 15min at 32°C. Semen aliquots were diluted further with TEYG, 0.5mgmL−1 CC+TG, or 1mgmL−1 CC+TG extender to a final concentration of 50×106 spermmL−1. Semen was then cooled to 4°C and frozen in a programmable freezer. Post-thaw sperm motion parameters were evaluated at 0, 2, 4, 6 and 24h with CASA. Semen fertility was determined by fixed-time AI using Hereford-cross cows (n=100). Synchronized cows were inseminated once with semen extended in TEYG, 1mgmL−1 CC+TG, or 1mgmL−1 CC+TG + 100 µmolmL−1 SS-31. Pregnancy was diagnosed by ultrasonography at 27 days post-insemination. Post-thaw sperm motion parameters were compared by ANOVA for repeated-measures, and pregnancy rates were compared using binomial linear mixed-model ANOVA. No differences in sperm motion parameters were detected among SS-31 treatments within extenders. Semen extended in TEYG or 1mgmL−1 CC+TG had greater total and progressive motilities at 0 and 2h post-thaw than semen extended in 0.5mgmL−1 CC+TG (P&lt;0.05). Pregnancy rates after fixed-time insemination did not differ among semen extender groups [TEYG: 15/25 (60%), 1mgmL−1 CC+TG: 19/34 (56%), 100 µmolmL−1 SS-31+1mgmL−1 CC+TG: 21/37 (57%)]. Addition of the cell permeating antioxidant SS-31 did not improve post-thaw semen quality or fertility. The CC+TG extender was as robust as conventional egg yolk extender in protecting bovine sperm during cryopreservation. This research was supported by NSERC Canada, the Government of Saskatchewan, and Agriculture and Agri-Food Canada.

89 Does progesterone block the nerve growth factor–induced luteinizing hormone surge in llamas?

The central inhibitory effects of progesterone on gonadotrophin secretion have been well documented in several species, including camelids. Nerve growth factor (NGF) in seminal plasma triggers ovulation in camelids and is thought to act at the level of the hypothalamus. The objective of the study was to determine the effect of progesterone on NGF-induced LH release in llamas. In Experiment 1, llamas were assigned to a low, medium, or high progesterone group (n=4 per group). The low progesterone group consisted of non-mated (non-ovulatory) llamas, the medium progesterone group consisted of mated llamas (luteal phase; 3–4 weeks pregnant), and the high progesterone group consisted of non-mated llamas given a single intramuscular (IM) dose of progesterone (300mg IM, Progesterone BioRelease LA). A jugular catheter was placed, and the following day llamas were given an intravenous dose of 1mg of NGF isolated from seminal plasma. Blood samples were taken every 30min from 1h before to 5.5h after NGF treatment. In Experiment 2, the pituitary LH response to gonadotrophin-releasing hormone (GnRH) was compared between llamas treated with either Progesterone BioRelease LA or saline (n=4 per group). Sixteen hours later, llamas in both groups were given 50µg of gonadorelin (GnRH) IV, and blood samples were collected by jugular puncture at 0.5h before and 0, 1, 2, and 4h after GnRH. Blood samples were centrifuged, and plasma was stored frozen until radioimmunoassay for LH and progesterone. Data are presented as mean±s.e.m. Data were analysed by one-way ANOVA for single-point and repeated-measures, and independent or paired t-tests. In Experiment 1, plasma progesterone concentrations in the low, medium, and high progesterone groups were 0.6±0.3, 8.2±0.4, and 14.9±1.2ng mL−1, respectively, at the time of NGF treatment (P&lt;0.05). Circulating concentrations of LH did not differ among progesterone groups (treatment, P=0.49; time, P&lt;0.01; treatment×time interaction, P=0.65). In all groups, LH concentrations were elevated within 30min of NGF administration, reached a peak by 2h, and remained elevated beyond the sampling period. Comparison of samples collected during the pretreatment period (i.e. −60, −30, and 0min), however, revealed that plasma LH concentrations in the high progesterone group were half that of the low and medium progesterone groups (P&lt;0.03). In Experiment 2, plasma progesterone concentrations in the progesterone- and saline-treated groups were 12.7±2.2 and 1.3±0.3ngmL−1, respectively (P&lt;0.01). Despite the difference in circulating progesterone concentrations, the LH response to GnRH treatment was not different between groups (treatment group, P=0.43; time, P&lt;0.01; treatment×time interaction, P=0.84). Results demonstrate a suppressive effect of progesterone on basal LH release in llamas, but no suppressive effect on NGF- or GnRH-induced surge release from the pituitary gland. Results are consistent with the hypothesis that the site of action of NGF is downstream of the hypothalamic site of action of progesterone. This research was supported by NSERC Canada.

22 Strategies for oocyte collection procedures in free-roaming bison herds

The study was conducted to test the feasibility of protocols for field collection of cumulus–oocyte complexes (COC) for invitro embryo production (IVP) in wild bison. The study was done with captive wood bison during the late anovulatory season (July). In Experiment 1, bison were assigned randomly to 2 groups (n=8/group) in which transvaginal ultrasound-guided COC collection was done in a chute without sedation or in lateral recumbency after chemical immobilization using a dart gun to compare collection efficiencies. In Experiment 2, a 2×2 design was used to examine the effects of superstimulation treatments [single-dose equine chorionic gonadotrophin (eCG) vs. multiple-dose FSH] and methods of drug administration (manual injection vs. field darting) on COC collection and IVP. Initial COC collection was done to serve as a non-superstimulated random start and to synchronize follicular wave emergence on the following day (Day 0; n=16). Half of the bison were given a single dose of 5000IU of eCG intramuscularly (IM) on Day −1. The other half were given 200mg of FSH IM on Day 0 and Day 2, followed by 2000IU human chorionic gonadotrophin IM on Day 4. Superstimulatory treatments were given by manual injection (chute restrained) to half of the bison in each group and by field darting in the other half. The COC were collected on Day 4 in the eCG group and Day 5 in the FSH group. Recovered COC were matured invitro for 25 to 28h at 38.8°C, fertilized (2×106 sperm mL−1) and co-incubated at 38.8°C in 5% O2, 5% CO2, and 90% N2 for 18h. Presumptive zygotes were denuded and cultured at 38.8°C in 5% O2, 5% CO2, and 90% N2. A commercially available IVF media set was utilised (IVF Bioscience). Data were compared by ANOVA and GLIMMIX. In Experiment 1, no difference was detected between chute-restrained vs. chemically immobilized groups in the time required to complete COC collection (6.9±1.0 vs. 8.9±1.0 min; P=0.2), the number of follicles aspirated (11.5±1.9 vs. 9.3±1.8; P=0.4), or the COC recovery rate [COC recovered/follicle aspirated; 58/92 (63%) vs. 44/69 (64%); P=0.9]. In Experiment 2, no differences were detected between superstimulation treatments (eCG vs. FSH) or method of drug administration (manual injection vs. field darting) for any endpoint. The number of medium (4.5–7.5 mm; 9.5±1.0 vs. 2.5±0.6; P&lt;0.0001) and large (&gt;8 mm; 8.6±0.8 vs. 3.4±1.5; P=0.004) follicles available was greater after superstimulation (groups combined) than without superstimulation (random start). Although there was no difference in the number of recovered compact COC between the superstimulated and non-superstimulated bison (8.9±1.3 vs. 6.2±1.7; P=0.2), the embryo production rate (number of embryos produced/number of COC matured) was greater after superstimulation than without superstimulation [54/189 (39%) vs. 19/108 (18%); P&lt;0.05]. We conclude that COC collection in a field setting is feasible and minimum-handling superstimulation with a single dose of eCG is as effective as a multiple-dose FSH protocol for the invitro production of embryos in bison. This research was supported by NSERC and Vetoquinol.

156 Oestrus response, corpus luteum function, and pregnancy rates following aromatase inhibitor treatment in beef heifers

In a previous study involving the use of the aromatase inhibitor letrozole to synchronise ovulation, incomplete luteolysis appeared to confound the synchronising effect in letrozole-treated heifers. Experiments were done to determine whether letrozole treatment interferes with luteolysis and affects the timing of oestrus (Experiment 1) and whether pregnancy rate is affected by the stage of the oestrous cycle during which letrozole treatment is initiated (Experiment 2). In Experiment 1, Hereford heifers were fitted with a HeatWatch sensor and given prostaglandin F2α (PGF2α). Ovulation (Day 0) was determined by daily ultrasonography, and on Day 3 heifers were given an intravaginal letrozole-releasing device or a sham device for 4 days (n=16 per group). Half of the heifers in each group were given PGF2α on Day 7 (PGF 1×) or on Day 7 and 7.5 (PGF 2×). Ultrasonography and blood sampling were done daily from device insertion to removal, every 12h for 72h following PGF2α and daily for 14 days following ovulation. In Experiment 2, heifers were randomly assigned to three groups (n=10-11 per group) in which a 4-day letrozole-releasing device treatment was initiated during metoestrus (Days 0-2), diestrus (Days 7-9), or pro-oestrus (Days 15-17). Prostaglandin F2α was given at device removal and again 12h later. Heifers were inseminated with frozen-thawed semen and given gonadotrophin-releasing hormone 66h after device removal. Ultrasonography and blood sampling were done twice daily from device removal until ovulation. End points examined included dominant follicle and corpus luteum (CL) diameters, onset of oestrus, and plasma concentrations of oestradiol determined by radioimmunoassay. Nominal data were compared using GENMOD, analysis of variance, or mixed model for repeated-measures and were expressed as means±s.e.m. Proportional data were analysed using chi-square. In Experiment 1, no main effects or interactions were detected between device or PGF treatment for onset of oestrus following PGF2α (overall 60.0±2.5h) or CL diameter profiles during luteolysis. Residual variation was reduced in the timing of the first PGF to ovulation in the PGF 2× group versus the PGF 1× group (5.6±2.2h vs. 15.2±3.2 h; P&lt;0.01). The CL diameter following ovulation was greater in the PGF 2× group compared with the PGF 1× group (P=0.03). Circulating plasma oestradiol during treatment was greater (P=0.04) in both the PGF 1× and sham groups. In Experiment 2, a greater proportion of heifers in the pro-oestrus group ovulated ≤24h after device withdrawal compared with the metoestrus and diestrus groups combined (6/11 vs. 0/22, respectively; P&lt;0.05). Pregnancy rate tended to be greater in the metoestrus group than in the diestrus group (10/11 vs. 6/10; P=0.08), and pregnancy rate in both groups was greater than that in the pro-oestrus group (0/11; P&lt;0.05). In conclusion, letrozole treatment did not interfere with luteolysis, and PGF2α given 2× at a 12-h interval on Day 7 after ovulation decreased variance in the timing to ovulation. Treatment initiated during metoestrus and diestrus yielded greater pregnancy rates than that started during pro-oestrus and warrants efficacy testing in a large fixed-time AI field trial. This research was supported by Alberta Agriculture and Forestry and by Dechra.

133 Test of minimum-intervention protocols for optimizing in vitro embryo production in bison

The study was done to determine whether minimal handling protocols for ovarian synchronization and ovarian superstimulation may be used to increase in vitro embryo production in bison. Ultrasound-guided cumulus-oocyte complex (COC) collection was done in a group of bison (n=23; random start) during the anovulatory season to synchronize new follicular wave emergence. The COC were classified morphologically (compact-good and -regular, expanded, denuded, degenerate) but not processed further. At the time of COC collection (Day 0), bison were assigned randomly to 3 groups and given 5mL of saline IM (non-superstimulated controls; n=11), 10 Armour units of pFSH (Antrin R10, Kyoritsu Seiyaku Corp., Tokyo, Japan) in 5mL of saline IM once per day from Day 0 to 2 (regular FSH; n=5), or 30 armour units of a sustained-release form of pFSH (Antrin R10Al, Kyoritsu Seiyaku Corp.) in 5mL of saline SC on Day 0 (long-acting FSH; n=7). On Day 4, a second COC collection was performed. Only compact COC were processed. The COC were matured in vitro for 25 to 28h at 38.8°C, fertilized (2×106 sperm mL−1) and co-incubated at 38.8°C in 5% CO2 for 18h. Presumptive zygotes were denuded and cultured at 38.8°C in 5% O2, 5% CO2 and 90% N2. Nominal data were compared by t-test and analysis of variance. Binomial data were compared among groups by chi-squared. There was no difference between the first (random) COC collection (n=23) and second collection (n=11 non-superstimulated controls) in the total number of follicles detected, but the distribution among size categories (3-4, 4-8, and &gt;8mm) differed, i.e. fewer in the 3 to 4mm category at the time of the second COC collection (12.2±1.0v. 8.1±1.4; P&lt;0.05). In the nonstimulated control group, there were no differences between the first and second COC collections in the number of follicles aspirated (12.7±1.0v. 10.4±1.5), number of COC collected (7.7±0.9v. 5.3±1.3), or in the categorical distribution of COC. At the second COC collection, the number of follicles in the &gt;8mm category was greater in the regular FSH group than in the control or long-acting FSH groups (2.8±0.5v. 1.1±0.3, and 1.9±0.4, respectively; P&lt;0.05), but no differences were detected in the number of follicles aspirated, COC collected, or in the categorical distribution of COC. The cleavage rate (of total oocytes submitted to in vitro maturation), recorded 2 days after IVF, was higher in the control group than in either the regular FSH or long-acting FSH groups [25/35 (71.4%), 7/28 (25.0%), 8/35 (22.8%); P&lt;0.0001]. The freezable embryo production rate, recorded 7 days after IVF, was greater in the control group than in the regular FSH or long-acting FSH groups [19/35 (54.3%), 5/28 (17.9%), 5/35 (14.3%); P&lt;0.01]. In conclusion, minimal-handling interventions used in the present study to increase embryo production in bison were not effective, likely as a result of the timing, frequency, and duration of superstimulation. A random start resulted in greater COC collection than collection 4 days after ovarian synchronization, and embryo production rates were greater in non-superstimulated bison. This work was supported by Parks Canada and Saskatchewan ADF. Antrin products donated by Kyoritsu Seiyaku Corp., Japan.

4 Induction of ovulation by kisspeptin in llamas

After mating, female camelids ovulate in response to nerve growth factor (NGF) present in semen (formerly referred to as ovulation-inducing factor). The ovulatory effect appears to be induced by stimulation of hypothalamic gonadotropin-releasing hormone (GnRH) neuronal activity and LH secretion. Recent studies have identified kisspeptin as an important mediator of GnRH secretion in several species. In the present study, we tested the hypothesis that kisspeptin is involved in the ovulatory pathway in llamas and investigated the mechanism of this effect. In Experiment 1, ovarian function in non-pregnant, non-lactating adult female llamas was synchronized by intramuscular administration of a GnRH analogue (50µg of gonadorelin acetate; Fertiline, Vetoquinol, Quebec, QC, Canada). When a growing dominant follicle ≥8mm in diameter was detected, llamas were assigned randomly to 3 treatment groups and given an intravenous dose of purified seminal NGF (1mg, single dose; n=5), kisspeptin (0.1mg kg−1 of body weight, 2 doses 1h apart; n=5), or PBS (n=4). The bioactive 10 amino acid fragment of murine kisspeptin was used. Ovulation and corpus luteum development were assessed by transrectal ultrasonography every other day from the day of treatment (Day 0) to Day 8. In Experiment 2, ovarian function among female llamas was synchronized, as in Experiment 1. When a growing dominant follicle ≥8mm in diameter was detected, llamas were given kisspeptin (0.1mg kg−1 of body weight IV, 2 doses 1h apart) beginning 2h after pretreatment with either a GnRH receptor blocker (cetrorelix acetate, 1.5mg per llama IV; Sigma, Oakville, ON, Canada; n=6) or saline (n=6). Llamas were examined 48h later by transrectal ultrasonography to detect ovulation and 8 days later to determine the presence of a corpus luteum. Chi-square tests were used to compare ovulation rates, and ANOVA for repeated measures was used to compare diameter profiles of the corpus luteum. In Experiment 1, ovulation rate did not differ between the NGF and kisspeptin groups (5/5 in each; 100%) and was greater than in the control group (0/4; 0% P&lt;0.05). Corpus luteum diameter did not differ between llamas that ovulated in response to treatment with NGF or kisspeptin (13.2±0.8 and 14.0±1.2mm on Day 8, respectively). In Experiment 2, none of the llamas pretreated with cetrorelix ovulated in response to kisspeptin treatment (0/6; 0%), whereas all of the llamas pretreated with saline ovulated in response to kisspeptin treatment and had a corpus luteum at Day 8 (6/6; 100%; P&lt;0.05). Results supported the hypothesis that kisspeptin induces ovulation in llamas. Because a GnRH receptor antagonist blocked ovulation, our interpretation is that the site of action of kisspeptin is upstream of the pituitary gland and involves control of GnRH release from the hypothalamus. These findings raise the possibility that kisspeptin mediates the ovulation-inducing effect of NGF. Research was supported by the Natural Sciences and Engineering Research Council of Canada.

198 Superovulatory response in cows undergoing aromatase inhibitor treatment

The aromatase inhibitor letrozole has been used in the treatment of infertility in women by inducing mild ovarian superstimulation or augmenting the ovarian response to FSH treatment. The effect has been attributed to an apparent up-regulation of FSH receptors on granulosa cells as a result of increased androgens (Weil et al. 1999 J. Clin. Endocrinol. Metab. 84, 2951-2956). The objective of this study was to determine whether letrozole will augment the superstimulatory response in FSH-treated cattle. Mature, non-lactating Holstein cows (n=30) were given 2 luteolytic doses of PGF2α 12h apart and scanned daily by transrectal ultrasonography to detect ovulation. Transvaginal ultrasound-guided ablation of follicles ≥5mm was performed in all cows as a group, at 5 to 8 days after ovulation. On the day of ablation, cows were assigned randomly to 2 groups (n=15 per group) and given either an intravaginal letrozole-releasing device or a blank device for 5 days. Coinciding with expected wave emergence (Day 0), cows in both groups were given 8 doses of 50mg of pFSH (Folltropin; Vetoquinol, Lure, France) IM at 12-h intervals, and PGF2α on Days 3 and 3.5. At the time of the second PGF2α, vaginal devices were removed and paint was applied to the tailhead to facilitate detection of oestrus. On Day 5, cows were given gonadotropin-releasing hormone (100mg gonadorelin) IM and artificially inseminated 12 and 24h later. Ova/embryos were collected by transcervical uterine flush on Day 12. The ovaries were examined by ultrasonography on Day 0, 3.5, 5, 6.5, and 12 to record the follicular and luteal response. Nominal data were compared between groups by t-test and by ANOVA for repeated-measures and are expressed as mean±s.e.m. Binomial data were compared by chi-squared test. The number of follicles at wave emergence did not differ between letrozole and control groups (24.6±3.1 and 26.5±3.3 respectively; P=0.68). There was no treatment effect or treatment×day interaction in the number of follicles &gt;8mm on Day 3.5, 5, and 6.5. Letrozole-treated cows exhibited oestrus later than controls (50.3±1.1h v. 40.7±2.0h after first PGF2α; P&lt;0.001) and had less variance in interval to oestrus (residuals, 3.1±0.48h v. 6.7±0.87 h; P&lt;0.01). The number of CL on Day 6.5 was lower in the letrozole group than in the control group (9.1±1.1v. 12.3±1.1; P=0.05). The proportion of ovulations (number of CL on Day 12 over number of follicles ≥3mm on Day 0) was lower in the letrozole group than in the control group (0.65±0.05v. 0.82±0.08; P=0.02). The total number of ova/embryos collected per cow did not differ between letrozole and control groups (5.0±1.9v. 5.4±1.8; P=0.75), nor did the number of transferable embryos differ (3.0±1.2v. 4.3±1.5; P=0.56). In conclusion, treatment with a letrozole-releasing device during ovarian superstimulation did not improve the superovulatory response or embryo collection rate in mature Holstein cows, but letrozole treatment resulted in more synchronous oestrus, which may be used in the design of a fixed-time AI protocol following superstimulatory treatment in cattle. This research was supported by the Alberta Livestock and Meat Agency.

Transcriptome analysis of granulosa cells after conventional vs long FSH-induced superstimulation in cattle

BACKGROUND

Prolongation of superstimulatory treatment appears to be associated with a greater superovulatory response and with greater oocyte maturation in cattle. A genome-wide bovine oligo-microarray was used to compare the gene expression of granulosa cells collected from ovarian follicles after differing durations of the growing phase induced by exogenous FSH treatment. Cows were given a conventional (4-day) or long (7-day) superstimulatory treatment (25 mg FSH im at 12-h intervals; n = 6 per group), followed by prostaglandin treatment with last FSH and LH treatment 24 h later. Granulosa cells were harvested 24 h after LH treatment.

RESULTS

The expression of 416 genes was down-regulated and 615 genes was up-regulated in the long FSH group compared to the conventional FSH group. Quantification by RT-PCR of 7 genes (NTS, PTGS2, PTX3, RGS2, INHBA, CCND2 and LRP8) supported the microarrays data. Multigene bioinformatic analysis indicates that markers of fertility and follicle maturity were up-regulated in the long FSH group.

CONCLUSION

Using the large gene expression dataset generated by the genomic analysis and our previous associated with the growth phase and gene expression changes post LH, we can conclude that a prolonged FSH-induced growing phase is associated with transcriptomic characteristics of greater follicular maturity and may therefore be more appropriate for optimizing the superovulatory response and developmental competence of oocytes in cattle.

133 In Vitro Embryo Production from Oocytes Collected from Non-Supertimulated Wood Bison (Bison bison athabascae) Following Maturation In Vitro Using Portable Incubators

This study was done to determine the feasibility of in vitro embryo production in wood bison during the anovulatory season, without ovarian superstimulation or follicle wave synchronization, to simulate collection conditions in a wild or field setting. The experiment provided the opportunity to compare embryo development using 2 different maturation media and incubator systems. The cumulus-oocyte complexes (COC) were collected by transvaginal ultrasound-guided follicle aspiration during May from non-superstimulated bison. Compact COC were allocated to 2 groups and matured in standard maturation medium using a portable gassed incubator, or in commercial medium using a portable non-gassed incubator. In the former (Standard), the COC were placed in a round-bottomed tube containing TCM-199 medium with 5% calf serum, 5 μg mL−1 LH, 0.5 μg mL−1 FSH, and 0.05 μg mL−1 gentamicin, and the tube was placed in a portable incubator with 5% CO2. In the latter (Commercial), COC were placed in a round-bottom tube containing the commercial medium (Boviteq, Saint-Hyacinthe, QC, Canada), and placed in a portable incubator without CO2. After 24 h of maturation, oocytes were fertilized in vitro (Day 0) in Brackett-Oliphant medium at 38.5°C in a conventional incubator with 5% CO2 humidified atmosphere. Presumptive zygotes were cultured in CR1aa plus 5% calf serum, at 38.5°C and in 5% CO2, 5% O2, and 90% N2 and high humidity. Cleavage was recorded on Day 3 and embryo development was recorded on Day 7. Cleavage and transferable embryo rates (calculated from the total number of oocytes submitted to IVF) were compared between groups by chi-squared test. No difference in cleavage rates was observed between Standard and Commercial treatment groups [68.1 (32/47) v. 79.2% (57/72), respectively; P = 0.25], nor in morula plus blastocyst rates on Day 7 (36.2 v. 45.8%, respectively; P = 0.39). However, the rate of transferable embryos (grade 1 and grade 2) on Day 7 was higher in the Commercial group (38.9 v. 12.8%; P < 0.01). Of the COC in the Commercial group, a higher number of morula plus blastocyst were observed to be compact good COC (>3 layers of cumulus cells) than compact regular COC (1-3 layers of cumulus cells) (66.7 v. 31.0% respectively; P < 0.05), along with a higher number of transferable embryos on Day 7 (60.0 v. 23.8%, respectively; P < 0.05). In conclusion, wood bison oocytes collected during the anovulatory season from non-superstimulated, non-synchronized bison and matured in vitro using portable incubators were competent to develop to the morula and blastocyst stages following IVF and culture. These results are important for future plans that require transporting oocytes from remote collection sites to the IVF laboratory, particularly with respect to the effectiveness of commercial maturation media which does not require CO2 supplementation. Research was supported by the Natural Sciences and Engineering Research Council of Canada.

12 Ovulation Timing Following an Aromatase Inhibitor-Based Synchronization Protocol in Beef Heifers and Cows

The study was conducted to determine the effects of parity/lactation and the timing of gonadotropin-releasing hormone (GnRH) treatment on the efficacy of a non-steroidal aromatase inhibitor-based synchronization protocol in cattle. Results from previous studies confirmed drug-release from a new letrozole-impregnated intravaginal silicone device, which was used in the present study. Hereford-cross cows with suckling calves (41 to 65 days postpartum; n = 30) and sexually mature heifers (n = 30), at random stages of the oestrous cycle, were given a letrozole intravaginal device for 4 days followed by a luteolytic dose of prostaglandin F2α (PGF2α). Following PGF2α treatment, animals were assigned randomly to 3 groups and given GnRH (100 μg of gonadorelin) intramuscularly at 48 or 60 h, or no GnRH (n = 10 cows and 10 heifers per group). Ovaries were examined by transrectal ultrasonography every 8 h starting at the time of PGF2α treatment to record follicle diameter and ovulation. After ovulation, ultrasonography was done every 24 h until Day 10 (Day 0 = ovulation) to assess the corpus luteum (CL) diameter profile. The timing of ovulation, diameter of the preovulatory follicle, synchrony of ovulation, and Day-7 CL diameter were compared using two-way ANOVA, and CL diameter profiles were compared by two-way ANOVA for repeated measures. There was no treatment × parity/lactation status interaction for any endpoint. The ovulation rate within 96 h of PGF2α treatment was not different between heifers and cows (24/30 v. 27/30; P = 0.14) or treatment group (18/20, 18/20, and 15/20 in the 48 h, 60 h, and no GnRH groups, respectively; P = 0.18). The interval from PGF2α treatment to ovulation was not influenced by parity/lactation (83.1 ± 2.4 h) but was shortest in the GnRH 48 h group (mean ± SEM; 74.2 ± 2.7 h, 85.6 ± 4.8 and 89.2 ± 4.1, respectively; P < 0.05). Similarly, the variation in the interval to ovulation (mean ± s.e.M of residuals) was not influenced by parity/lactation (16.0 ± 2.0 h), but was lower in the GnRH groups than the no-GnRH group (P < 0.01), and tended to be lower (P = 0.1) in the GnRH 48-h v. 60-h group (10.0 ± 2.8, 14.2 ± 3.5, and 24.1 ± 3.1 h, respectively). The maximum diameter of the ovulatory follicle was larger for cows than heifers (17.0 ± 0.4 v. 15.1 ± 0.5; P < 0.01), and was smaller in the GnRH groups than the no-GnRH group (15.3 ± 0.3, 15.4 ± 0.7 and 17.3 ± 0.5 mm, respectively; P < 0.01). The diameter of the CL on Day 7 was larger for cows than heifers (22.3 ± 0.8 v. 20.2 ± 0.6 mm; P < 0.05) and was influenced by treatment (21.9 ± 0.5, 19.5 ± 0.7, 22.3 ± 1.1 mm, respectively; P = 0.05). A tendency for a treatment effect on CL diameter profile (P = 0.1) was attributed to a smaller profile in the GnRH 60-h group. In conclusion, GnRH treatment 48 h after PGF2α treatment increased synchrony of ovulation without adverse effects on ovulating follicle diameter or resulting CL growth, and may be incorporated into a novel steroid-free oestrous synchronization protocol for use in beef heifers and lactating cows. Research was supported by the Alberta Livestock and Meat Agency and Vencofarma, Brazil.

3 Animal Protein-Free Semen Extender for Fixed-Time Insemination of Beef Cows

Current semen cryopreservation protocols include the use of animal products, such as egg yolk, in semen extenders, which raises important biosecurity concerns related to the transmission of infectious agents. Therefore, there is a need for alternatives to animal proteins in semen extenders. Cholesterol-cyclodextrin (CC) has been used as an adjunct in semen extenders to facilitate the delivery of exogenous cholesterol into sperm plasma membranes. The purpose of this study was to determine the fertility potential of semen extended with cholesterol of plant origin (PhytoChol, Wilshire Technologies, NJ, USA) in a fixed-time insemination program for beef cows. Semen was collected by electroejaculation from mature Simmentals bulls (n = 4 bulls, 4 replicates/bull) and analysed using computer-assisted semen analysis (CASA). Ejaculates from different bulls with ≥200 × 106 sperm mL−1 and ≥60% total motility were pooled. The pooled ejaculates were distributed into 3 treatments and diluted to 50 × 106 mL−1 in Tris-citric-acid base extenders containing either egg yolk (20% vol/vol egg yolk, control), 0.5 mg of CC per mL of semen, or 1.0 mg of CC per mL of semen. Glycerol (7% vol/vol) was added to each extender. Extended semen was loaded into 0.5-mL straws and frozen to –196°C. Post-thaw sperm motility was analysed using CASA. Ovulation was synchronized among multiparous beef cows using 1 of 3 protocols: (1) 5-day intravaginal progesterone-releasing device (PRID) and prostaglandin F2α PGF2α) treatment on the day of PRID removal (n = 37 on random days of cycle); (2) oestradiol + progesterone treatment and 7-day PRID followed by PGF2α on the day of PRID removal (n = 37 on random days of cycle); or (3) PGF2α alone (n = 19 on Day 7 to 9 from ovulation). Cows were treated with gonadotropin-releasing hormone (GnRH) and assigned randomly to be inseminated with 1 of the 3 semen treatments 72 h after PGF2α treatment. Ovulations were confirmed and pregnancies were diagnosed 28 to 35 days after insemination by ultrasonography. Post-thaw sperm motility was compared among extenders by analysis of variance. Pregnancy rates were compared among groups by generalized linear mixed model. Total motility (52 ± 3%, 59 ± 3%, and 62 ± 7%) and progressive motility (47 ± 3%, 54 ± 3%, and 58 ± 6%) did not differ among the egg yolk, 0.5 mg CC, and 1.0 mg CC extenders, respectively. There were no differences in pregnancy rates among synchronization groups; therefore, data were combined to compare the effects of semen extender. Four cows were excluded due to improper synchronization treatment. Pregnancy rates of cows inseminated with egg yolk (n = 31), 0.5 mg CC (n = 31), and 1.0 mg CC (n = 27) semen were 32, 74, and 52%, respectively (P < 0.05). Fertility in cattle inseminated using semen extended with cholesterol of plant origin has not been previously reported. We conclude that plant cholesterol may be used to replace animal proteins (egg yolk or milk origin) in bovine semen cryopreservation. Research supported by grants from the Saskatchewan Agricultural Development Fund, Agriculture and Agri-Food Canada, and Alberta Livestock and Meat Agency.

105 P75 Neuronal Cells and Fibers in the Bovine Ovary

Neurotrophins are molecules involved in the development and survival of neurons and its cellular projections. Results of recent studies have implicated the local role of the high affinity neurotropin receptor, trkA, in bovine ovarian follicle selection and early luteogenesis (Carrasco et al. 2016 Reprod. Biol. Endocrinol. 14, 47), but innervation and neuropeptide control remains an unexplored aspect of ovarian function. P75 is the low-affinity receptor for all neurotrophins and is expressed in ovarian tissue. The objective of this study was to explore the distribution of P75 neurons and fibres within the ovary and to examine the relationship of these components with follicular development. The ovaries of cows (n = 5) were collected at the time of slaughter, 36 h after induced luteolysis (i.e. proestrus). The ovaries were fixed in 4% paraformaldehyde for 48 h, and samples from the ovarian hilus, medulla, and cortex (3 blocks per ovary) were cryo-sectioned (20–50 µm). Tissue sections were incubated for 48 h with a rabbit antibody against rat P75 or a mouse monoclonal antibody against neurofilament. Immunodetection was visualised by an amplification procedure with horseradish peroxidase using nickel DAB as a chromogen. Sections were counterstained with nuclear fast red for follicle identification. Immunoreactive cell bodies were counted in 10 to 20 fields (40×) per section, and data were expressed based on ovarian areas (cortex, medulla, or hilus) as an average count per 40× field per animal. Data among ovarian regions were compared by ANOVA; differences were considered significant when P < 0.05. Antral follicles ≤5 mm displayed strong immunoreactivity in the theca layer, without reaction in the granulosa cells. In contrast, preovulatory follicles were devoid of P75 immuno-reactivity in the theca layer. Oval P75 immunoreactive neuron-like cells were present in all ovarian areas studied. The neuronal nature of the P75 immunoreactive cells was confirmed by the presence of a similar pattern when adjacent sections were stained for neurofilaments, a protein characteristic of neurons. In the stroma of the ovarian cortex and medulla, neurons were present individually (scattered) rather than grouped; however, a dense network of neurons and fibres was detected immediately beneath the ovarian surface epithelium. No differences between the cortex, medulla, and hilus were found in the mean number of immunoreactive cells (10.6 ± 2.8, 14.4 ± 3.6 and 13.9 ± 2.0 cells/40× field, respectively). Immunoreactive neuron-like cells and fibres were in close proximity to blood vessels in the ovarian medulla. Corpora lutea were devoid of P75 immunoreactivity. In conclusion, results document the existence of a neuronal network in the bovine ovary, displaying an association with follicles at different stages of development. The abundance of neuronal components (i.e. neuron cell bodies and axons) in the ovarian stromal and surface epithelium implies a role of innervation (either extrinsic or intrinsic) in the control of ovarian follicular development and function. Research was supported by the Natural Sciences and Engineering Research Council of Canada.

4 Relationship Between Ovarian Vascularity, Cumulus–Oocyte Morphology and Luteal Development in Four-Month-Old Calves After FSH Stimulation

The objectives of this study were to determine the effect of LH on the blood flow to the ovaries of 4-month-old calves after 2 FSH stimulation protocols, and to examine the relationship between ovarian vascularity after superstimulation to the morphology of the cumulus–oocyte complexes (COC) and luteal function. We hypothesise that ovarian vascularity (detected by 3-dimensional (3D) analysis of Doppler ultrasound cineloops) will increase in response to LH, and the magnitude of change in vascularity would be predictive of (1) a greater proportion of expanded COC, (2) greater development of luteal tissue volume and vascularity at 3 and 7 days after follicle aspiration, and (3) higher levels of plasma progesterone. Ovarian superstimulation was initiated at the beginning of an induced follicular wave in 4-month-old beef calves (n = 16), and beef cattle >16 months of age (control group, adults; n = 8) using either a traditional 4-day or an extended 7-day FSH protocol (n = 8 calves and n = 4 controls per group). Power Doppler ultrasound cineloops were recorded immediately before (i.e. 12 h after the last FSH treatment) and 24 h after LH treatment (before ultrasound-guided follicular aspiration for oocyte collection) to assess ovarian vascularity, and 3 and 7 days after follicular aspiration to assess luteal tissue volume and vascularity. Video segments were analysed in Fiji and Imaris software to obtain the 3D ovarian vascularity index (ratio of blood flow volume to tissue volume). The ovarian vascularity index tended to increase >1.7-fold in response to exogenous LH in both prepubertal calves (pre-LH 1.5 ± 0.4% v. post-LH 2.6 ± 0.7%; P = 0.08) and adult cattle (pre-LH 2.2 ± 0.6% v. post-LH 4.7 ± 0.9%; P = 0.07). Calves with a recovery of >75% of expanded COC had a higher ovarian vascularity index (10.7 ± 2.6% v. 4.8 ± 1.6%; P = 0.06) and luteal vascularity index (15.7 ± 4.5% v. 5.7 ± 2.1%; P < 0.05) 7 days after aspiration than those with <75% expanded COC. Calves in the 7-day FSH protocol had >10-fold higher concentration of plasma progesterone on Day 3 (12.7 ± 7.3 ng mL−1 v. 1.2 ± 0.4 ng mL−1; P < 0.05) and Day 5 (50.6 ± 28.0 ng mL−1 v. 4.5 ± 1.0 ng mL−1; P < 0.05), and ~2-fold higher luteal vascularity index at 7 days after follicle aspiration (13.7 ± 4.6% v. 7.7 ± 2.8%; P < 0.05) than calves in the 4-day FSH protocol, whereas no difference (P > 0.05) was found in control (adult) animals. In conclusion, there was an increase in ovarian vascularity resulting from LH treatment in prepubertal calves and adult cattle. A greater proportion of expansion of COC at 24 h after LH treatment (an indicator of follicular maturation) was related to higher ovarian and luteal vascularity on Day 7 after collection in prepubertal calves, but not in adults. Luteal vascularity on Day 3 was reflective of plasma progesterone concentration, and prepubertal calves in the 7-day FSH protocol had greater plasma progesterone than calves in the 4-day FSH protocol. The use of FSH in calves allows a greater number of follicles for oocyte collection as it does in adult cattle. Research was supported by an NSERC grant.

104 Distribution of Gonadotropin-Releasing Hormone and Kisspeptin Neurons in the Preoptic Area and Hypothalamus During the Estrous Cycle in Cows

Gonadal steroids hormones indirectly regulate gonadotropin-rleasing hormone (GnRH) secretion. Kisspeptin (Kp) co-expresses steroid receptors and modulates GnRH release. The objective of the study was to characterise the number and proportion of GnRH and Kp immunoreactive cells and their association in the preoptic area (POA) and hypothalamus during different phases of the oestrous cycle in cows. Daily ovarian ultrasonography was performed to detect follicle development and ovulation (Day 0) after prostaglandin treatment. On Day 5, cows were assigned randomly to the following groups: proestrus (n = 2), metestrus (n = 2) or diestrus (n = 3). Cows in the diestrus group were killed on Day 8. Cows in the proestrus and metestrus groups were given luteolytic dose of prostaglandin on Day 5.5 and Day 6 and were killed on Day 7 and 24 h after the ensuing ovulation, respectively. Cow heads were perfused with 4% paraformaldehyde via the carotid arteries to fix the brain in situ. The brain-stem (rostral portion of the POA to the mamillary body) was isolated by dissection and placed in 4% paraformaldehyde for 48 h. Following cryoprotection, the tissue block containing the POA and hypothalamus was frozen at –80°C and sectioned serially at a thickness of 50 mm using a cryostat microtome. Every 20th free-floating section was processed for double labelling using 2 sequential immuno-peroxidase reactions and ABC staining; Kp was immuno-labelled with Nickel-DAB at a dilution of 1:10,000 rabbit anti-kisspeptin (AC566, INRA, France), and GnRH was stained with DAB using 1:40,000 rabbit anti-GnRH (LR-5, Dr Benoit). The numbers of neuron cell bodies and fibres were recorded in different areas of the POA and the hypothalamus by brightfield microscopy using 10× and 40× objective lenses. Data were compared among groups by ANOVA. Major aggregations of Kp cells were localised in the mPOA, OVLT, and ARC. Overall, the number of Kp cells was higher in the metestrus v. diestrus group (719 ± 94 v. 378 ± 8; P = 0.01), but was similar to the proestrus group (558 ± 9). The number of Kp cells in the POA (mPOA, OVLT) tended to be higher in the metestrus v. diestrus group (395 ± 56 v. 147 ± 44; P = 0.06), and was intermediate in the proestrus group (206 ± 6). The number of Kp cells in the ARC did not differ among groups (metestrus 310 ± 26, diestrus 206 ± 53, proestrus 321 ± 99; P = 0.4). The number of GnRH cells bodies was not different among groups (metestrus 40 ± 3, diestrus 50 ± 9, proestrus 43 ± 8; combined; P = 0.8), and the distribution was higher in the POA (metestrus 25 ± 2, diestrus 30 ± 3, proestrus 33 ± 2) than hypothalamus. The proportion of GnRH cells in apposition to Kp fibres tended to be highest in the proestrus v. metestrus and diestrus groups (50.5 ± 1% v. 34.1 ± 9% and 31.4 ± 3%; P = 0.09). In conclusion, the number of Kp immunoreactive cells, but not GnRH cells, present in the POA and hypothalamus changed among different phases of the oestrous cycle due primarily to an increase in number of Kp cells in POA during metestrus. The proestrous phase was associated with an increase in apposition between Kp fibres and GnRH cells.

62 Will Gonadotropin-Releasing Hormone Treatment Hasten the Onset of Puberty in Peripubertal Heifers?

Treatment with gonadotropin-releasing hormone (GnRH) has been used to induce ovulation in prepubertal heifers. The objective of this study was to evaluate whether peripubertal heifers will continue to ovulate at regular intervals (i.e. attain puberty) after GnRH treatment. Prepubertal crossbred Hereford heifers, 11.0 ± 0.5 months of age, 344 ± 26 kg of body weight, and at random stages of ovarian follicular wave status, were assigned to 2 groups (age- and weight-matched) and given GnRH (n = 24) or no treatment (Control, n = 22) on Day 0. Ovarian ultrasonography was performed every second day from Day 0 to 44 to record the size of 2 largest follicles and the corpus luteum (CL). Thereafter, examinations were done every 4 days until the third ovulation or Day 100, whichever came first. The first and second interovulatory intervals (IOI) were categorized as short (<12 days), normal (16-24 days), or long (>24 days), and the onset of the puberty was defined by the occurrence of 2 consecutive short or normal IOI (i.e. 3 uninterrupted ovulations). Proportional data were compared among groups by chi-squared test. Single-point measurements were compared by analysis of variance and multiple comparisons were made using Tukey’s test. Two heifers (one in each group) failed to ovulate during the experiment. The diameter of the largest follicle on Day 0 did not differ (P = 0.31) between the GnRH and Control groups (12.6 ± 0.37 mm and 13.1 ± 0.29 mm, respectively). The proportion of heifers that ovulated by Day 4 after treatment was higher in the GnRH than in the Control group (9/24 v. 1/22; P < 0.01). However, the proportion of heifers in the GnRH v. Control groups that ovulated twice (19/24 v. 18/22; P = 0.60) or 3 times (9/24 v. 9/22; P = 0.81) did not differ. The age at first ovulation tended to be younger in the GnRH group than in the Control (12 ± 0.97 v. 13 ± 0.90 months; P = 0.07), but the effect was attributed only to those heifers that ovulated in response to GnRH treatment (n = 9). The age at first ovulation was 11.2 ± 0.50, 12.7 ± 0.73, and 12.6 ± 0.90 months in GnRH-responders, non-responders, and the control group, respectively (P < 0.0001). One heifer that ovulated in response to GnRH treatment failed to ovulate again during the study period (Day 100). In 87.5% (7/8) of the heifers that responded to GnRH treatment and ovulated at least twice, the first IOI was long (55.5 ± 8.3 days). When data were combined between the GnRH non-responders and the control group (n = 35), the first IOI was short (8.9 ± 0.4 days) in 77% of the heifers, and the second IOI was of normal length (18.8 ± 0.9 days) in 93% of heifers. The age at the second ovulation in GnRH responders (12.7 ± 0.3 months) was similar (P = 0.82) to the age at first ovulation in GnRH non-responders (12.9 ± 0.1 months) and the control group (12.7 ± 0.2 months), indicating that GnRH treatment did not hasten the onset of continuous cyclicity. In conclusion, although GnRH treatment induced first ovulation in some peripubertal heifers, treatment did not hasten the onset of puberty. Research was supported by the Natural Sciences and Engineering Research Council of Canada.

Nerve growth factor from seminal plasma origin (spβ-NGF) increases CL vascularization and level of mRNA expression of steroidogenic enzymes during the early stage of Corpus Luteum development in llamas

The objectives of the study were to determine the effect of seminal plasma β-NGF on Corpus Luteum morphology and function and level of mRNA expression of steroidogenic enzymes. Llamas were assigned (n = 12/per group) to receive an intramuscular dose of: (a) 1 ml phosphate buffered saline (PBS), (b) 5 μg gonadorelin acetate (GnRH), or (c) 1.0 mg of purified llama spβ-NGF. Ovaries were examined by transrectal B-mode ultrasonography from treatment to ovulation (Day 0 = treatment). B mode/Power Doppler ultrasonography and blood samples collection were performed at Days 4, 8 and 10 (n = 3 llamas per treatment group/per time point) to determine CL diameter, vascularization and plasma progesterone concentration respectively. Plasma progesterone concentration was analyzed in all llamas at Day 0. Then females were submitted to ovariectomy at Days 4, 8 and 10 (n = 3 llamas/treatment/time), CL was removed to determine vascular area, proportion of luteal cells and CYP11A1/P450scc and STAR expression by RT-PCR. Ovulation was similar between llamas treated with GnRH or spβ-NGF and CL diameter did not differ between GnRH or spβ-NGF groups by Day 4, 8 or 10. Vascularization area of the CL was higher (P < 0.01) in llamas from the spβ-NGF than GnRH-treated group by Day 4 and 8. Plasma progesterone concentration was higher (P < 0.05) in llamas from the spβ-NGF compared to females of GnRH group by Day 4 and 8. The proportion of small and large luteal cells did not differ between GnRH or spβ-NGF groups by Day 8. CYP11A1/P450scc was upregulated 3 folds at day 4 and 10 by spβ-NGF compared to GnRH. STAR transcription was 3 folds higher at day 4 in females treated with spβ-NGF. In conclusion, the luteotrophic effect of spβ-NGF could be related to an increase of vascularization and up regulation of CYP11A1/P450scc and STAR transcripts enhancing progesterone secretion.

39 FERTILITY POTENTIAL OF FROZEN-THAWED WOOD BISON SEMEN USING EXTENDER WITHOUT EXOGENOUS PROTEIN

Cryopreservation of semen free of infectious agents is critical for the recovery and preservation of genetic diversity in Canada’s threatened wood bison populations. Egg yolk is a common constituent of conventional semen extenders, but it raises biosafety concerns related to transmission of infectious agents. The purpose of this experiment was to determine the fertility potential, both in vitro and in vivo, of semen frozen without the use of exogenous protein but with addition of cholesterol loaded cyclodextrin (CLC). Semen was collected by electro ejaculation from 4 wood bison bulls. Fresh sperm total motility and concentration were analysed using a computer-assisted sperm analyzer. Ejaculates with total sperm motility of >60% and a concentration of >200 × 106 sperm mL–1 were selected and pooled among bulls. For the control group, pooled semen was diluted to 50 × 106 sperm mL–1 with conventional extender containing 20% egg yolk and 7% glycerol. For the test group, pooled semen was diluted to 100 × 106 sperm mL–1 in Tris-citric acid buffer and incubated with 2 mg mL–1 CLC for 15 min before 1 : 1 dilution with 14% glycerol extender. Extended semen was placed in 0.5-mL straws, cooled, and frozen. Post-thaw motility analysis was conducted using a computer-assisted sperm analyzer, and the 2 collections with highest post-thaw motility were selected for fertility testing. Heterologous IVF was conducted using bovine oocytes obtained from an abattoir. After 20 to 22 h of in vitro maturation, the cumulus-oocyte complexes were placed into drops with either control or test semen. After 18 h, potential zygotes were denuded and moved to culture media. Cleavage and blastocyst rates were assessed on Day 4 and 8, respectively, from oocyte collection. The fertility potential of the semen was also tested in vivo using synchronized wood bison cows. At 24 h after hCG treatment, bison cows were assigned randomly to 2 groups and inseminated twice, 12 h apart, with frozen-thawed control semen (n = 23) or test semen (n = 23). Pregnancy was assessed 34 to 36 days after insemination by transrectal ultrasonography. Total sperm motility (mean ± standard error of the mean) of fresh semen was 80.2 ± 3.3%. The post-thaw motility was 41.7 ± 2.9% and 44.6 ± 3.3% for control and test semen, respectively. The cleavage rates of bovine oocytes fertilized in vitro with bison semen from the control group (n = 278) and test group (n = 299) were 49.9 ± 2.1% and 41.3 ± 4.5%, respectively, and the blastocyst rates were 17.7 ± 1.7% and 17.3 ± 2.5%, respectively. Pregnancy rates of wood bison artificially inseminated with control and test semen were 39 and 0%, respectively. In conclusion, wood bison semen frozen with CLC (without exogenous protein) resulted in post-thaw motility and in vitro fertility potential comparable to that of conventional egg yolk extender. However, CLC semen failed to fertilize in vivo, perhaps because of disruption of the processes of capacitation. The dichotomy between in vivo and in vitro results was surprising. It may be necessary to exercise caution when using IVF as a tool to assess fertility in vivo.

122 TIMED ARTIFICIAL INSEMINATION IN WOOD BISON USING FROZEN-THAWED SEMEN

Recent progress with methods to control ovulation and semen cryopreservation in Wood Bison was the impetus to test the feasibility of timed AI to facilitate reclamation of this threatened species. A 2 × 2 design was used to compare the efficacy of 2 ovulation synchronization techniques and 2 semen cryopreservation protocols. Female Wood Bison were assigned randomly to 2 groups (n = 24/group) in which ovarian synchronization was induced by ultrasound-guided ablation of follicles >5 mm or intramuscular treatment with 2.5 mg of estradiol 17B + 50 mg of progesterone (E+P) in canola oil. A progesterone-releasing intravaginal device (PRID) was placed at the time of follicle ablation (for 5 days) or E+P treatment (for 8 days) in the respective groups. A luteolytic dose of prostaglandin was given at the time of PRID removal, and 2500 IU of hCG was given IM 3 days later. Bison were inseminated 24 and 36 h after hCG treatment using frozen-thawed semen. The semen was collected by electro-ejaculation from 4 Wood Bison bulls, pooled, and divided into aliquots diluted in either egg-yolk extender (EY) or cholesterol-loaded cyclodextrin extender (CLC). Half the bison in each synchronization group were inseminated with either EY- or CLC-extended semen. Bison were examined by ultrasonography every 12 h beginning on the day of hCG treatment for 3 days or until ovulation was detected, whichever occurred first. Pregnancy diagnosis was made by ultrasonography 34–36 days after insemination. Two bison were excluded during the experiment because of handling difficulty; therefore, the total number of bison used was 46. Ovulation rate and interval to ovulation were compared between synchronization groups by chi-square and t-test, respectively. Pregnancy rates were compared among groups by 2-way ANOVA after transforming data to arcsin. The ovulation rate was not different between synchronization groups [combined mean, 37/46 (80%)], nor was the degree of synchrony, as assessed by the residuals (variation from the mean) in the respective groups. However, the diameter (mean ± standard error of the mean) of the dominant follicle at the time of hCG treatment was smaller in the follicle ablation group than in the E+P group (10.5 ± 0.6 v. 13.9 ± 0.6; P < 0.04), and the interval from hCG treatment to ovulation tended to be longer (35.3 ± 1.6 v. 31.8 ± 1.3 h; P ≤ 0.10). Pregnancy rate was not affected by synchronization procedure, but pregnancy was detected only in the EY-inseminated group (9/23 v. 0/23; P < 0.01). Despite that post-thaw sperm motility was similar for EY and CLC semen (41.7 ± 2.9 and 44.6 ± 3.3%; respectively), CLC-treated semen failed to impregnate bison in vivo. We concluded that synchronization and timed insemination with frozen-thawed semen is feasible in Wood Bison. Of the 23 bison inseminated with EY-extended semen, 21 ovulated (91%), and of those that ovulated 9 became pregnant (43%). Both synchronization schemes were effective, but the ablation protocol may be improved by an additional day between ablation and hCG treatment. We thank Vetoquinol Canada and Merck Animal Health for providing hormone treatments.

183 IN VITRO EMBRYO PRODUCTION: A TOOL TO PRESERVE THE THREATENED WOOD BISON (BISON BISON ATHABASCAE)

In vitro embryo production is being developed as a tool to restore genetic diversity and eliminate endemic disease in wood bison. In a recent study in wood bison, we found that more oocytes reached maturity after 30 h v. 24 h of in vivo maturation following hCG treatment (Cervantes et al. 2014 Reprod. Fertil. Dev. 26, 199). An additional 4 h of in vitro maturation after an in vivo maturation period of 30 h also had a positive effect on developmental competence. The present study was designed to test the hypothesis that extending the in vivo maturation time (i.e. extending the interval between hCG treatment and cumulus-oocyte complex (COC) collection) from 30 to 34 h will improve in vitro embryo production in wood bison. Follicular wave development was synchronised among female wood bison (n = 28, 6 to 10 years old) by transvaginal follicular ablation. The study was done in 4 replicates (n = 7 bison per replicate). Bison were given FSH 1 day (300 mg) and 3 days (100 mg) after ablation for ovarian superstimulation, and hCG (2500 IU) 5 days after ablation to induce COC maturation in vivo. Bison were divided randomly into 2 groups (n = 14/group) in which COC were collected transvaginally at either 30 h or 34 h after hCG treatment. Expanded COC from the 30 h group were fertilised after 4 h of in vitro maturation, while expanded COC from the 34 h group were fertilised immediately. Oocytes and sperm were co-incubated (Day 0 = day of fertilization) for 18 h at 38.5°C in 5% CO2 in air and high humidity. Presumptive zygotes were cultured in 4-well dishes containing 500 μL well–1 of CR1aa medium at 38.5°C, 5% CO2, 5% O2, 90% N2 and high humidity, and assessed on Days 3, 7, and 8 (Day 0 = day of fertilization). Data were compared between groups by Chi-squared analysis. No effect of replicate was found. Compared to the 30 h group, the 34 h group had a greater cleavage rate [55/74 (74%) v. 49/86 (57%); (P < 0.05)], and a greater blastocyst rate on Day 7 [25/74 (34%) v. 9/86 (10%); (P < 0.05)] and Day 8 [(40/74 (54.1%) v. 32/86 (37.2%); (P < 0.05)]. We concluded that an extended period of in vivo maturation is beneficial for embryo production after in vitro fertilization in wood bison. We thank Vetoquinol Canada for providing FSH (Folltropin-V) and hyaluronan (MAP-5) and thank Merck Animal Health for hCG (Chorulon).

135 SHORT-TERM OVARIAN EFFECTS OF UNILATERAL OVARIECTOMY IN COWS

Classical studies established that the removal of one of the paired organs produces a compensatory effect on the remaining organ. In the bovine ovary this aspect has not been examined in detail. We took advantage of follicular and luteal profiles from a previous study to retrospectively examine the effects of ovariectomy before and after ovulation on follicular dynamics of the remaining ovary in cattle. To characterise the prevalence and distribution of tyrosine kinase receptor A in the bovine ovary, the original design involved unilateral ovariectomy of cows at different stages of the periovulatory period. For the purposes of the present study, we combined data into 2 groups, a preovulatory group (n = 6 cows) and a post-ovulatory group (n = 5 cows), to provide sufficient data for statistical interpretation. The cows were examined daily by transrectal ultrasonography to determine the ovarian status. For the preovulatory group, a luteolytic dose of prostaglandin was administered when the dominant follicle of the second follicular wave reached ≥10 mm, and the ovary containing the dominant follicle was removed within 48 h. For the post-ovulatory group, ovariectomy was performed on the ovary containing the newly formed corpus luteum between Days 2 to 6 (Day 0 = ovulation). Unilateral ovariectomy was performed by colpotomy under caudal epidural anaesthesia using a chain ecraseur. After ovariectomy, cows were examined daily by ultrasonography from ovariectomy to the completion of an interovulatory interval (period between 2 ovulations). Single-point data were compared between groups by t-test, and binomial data were compared between groups by Fisher’s exact test. Double ovulations were detected in 3/6 ovariectomized in the preovulatory period and 2/5 ovariectomized in the post-ovulatory period. The first ovulation after ovariectomy tended to occur earlier in the preovulatory group than in the post-ovulatory group (P = 0.08), which was attributed primarily to the development of oversized persistent dominant follicles (~20 mm in diameter for ≥7 days in absence of a corpora lutea) in 2 of 5 cows in the post-ovulatory ovariectomy group. The interovulatory interval after ovariectomy was shorter in the post-ovulatory group than in the preovulatory group (14.6 ± 0.3 v. 20.3 ± 0.6 days; P = 0.01). No distinct patterns were detected in follicular and luteal dynamics between the pre- and post-ovulatory ovariectomy groups. The number of follicles ≥3 mm detected by ultrasonography was greater in the post-ovulatory ovariectomy group than in the preovulatory group on Days 6, 7, 8, and 16 of the first interovulatory interval after ovariectomy. In conclusion, results of this retrospective study support the concept that follicular and luteal effects of removal of one ovary are influenced by the timing of ovariectomy relative to ovulation. A prospective study involving a comparison of ovarian dynamics of the same cows before and after unilateral ovariectomy will provide a better understanding of the disruption that take place and the mechanisms controlling it. Research was supported by the Natural Sciences and Engineering Research Council of Canada.

Organelle reorganization in bovine oocytes during dominant follicle growth and regression

BACKGROUND

We tested the hypothesis that organelles in bovine oocytes undergo changes in number and spatial distribution in a manner specific for phase of follicle development.

METHODS

Cumulus-oocyte-complexes were collected from Hereford heifers by ultrasound-guided follicle aspiration from dominant follicles in the growing phase (n = 5; Day 0 = ovulation), static phase (n = 5), regressing phase (n = 7) of Wave 1 and from preovulatory follicles (n = 5). Oocytes were processed and transmission electron micrographs of ooplasm representing peripheral, perinuclear and central regions were evaluated using standard stereological methods.

RESULTS

The number of mitochondria and volume occupied by lipid droplets was higher (P < 0.03) in oocytes from regressing follicles (193.0 ± 10.4/1000 μm(3) and 3.5 ± 0.7 %) than growing and preovulatory stages (118.7 ± 14.4/1000 μm(3) and 1.1 ± 0.3 %; 150.5 ± 28.7/1000 μm(3) and 1.6 ± 0.2 %, respectively). Oocytes from growing, static and preovulatory follicles had >70 % mitochondria in the peripheral regions whereas oocytes from regressing follicles had an even distribution. Oocytes from growing follicles had more lipid droplets in peripheral region than in central region (86.9 vs. 13.1 %). Percent surface area of mitochondria in contact with lipid droplets increased from growing (2.3 %) to static, regressing or preovulatory follicle stage (8.9, 6.1 and 6.2 %). The amount, size and distribution of other organelles did not differ among phases (P > 0.11).

CONCLUSIONS

Our hypothesis was supported in that mitochondrial number increased and translocation occurred from a peripheral to an even distribution as follicles entered the regressing phase. In addition, lipid droplets underwent spatial reorganization from a peripheral to an even distribution during the growing phase and mitochondria-lipid contact area increased with follicle maturation.

363 EXTENDING THE IN VIVO MATURATION TIME TO PERMIT FLEXIBLE TIMING OF OOCYTE COLLECTION IN SUPERSTIMULATED WOOD BISON (BISON BISON ATHABASCAE)

Wood bison are a species threatened by endemic brucellosis and tuberculosis. Reproductive technologies are being developed in an effort to ensure the genetic diversity of wild wood bison, and to prevent disease transmission to healthy bison, livestock, and humans. For the purposes of IVF, recent results revealed that cumulus cell expansion was more extensive in in vivo- v. in vitro-matured cumulus-oocyte complexes (COC), and more oocytes reached maturity after 30 v. 24 h of in vivo maturation following hCG treatment (Cervantes et al. 2013 Reprod. Fert. Develop. 25, 283). An experiment was designed to determine the effects of an additional 4 h of in vivo maturation on follicle development, unwanted ovulation, and COC collection efficiency. Wood bison cows (n = 28) underwent transvaginal ultrasound-guided follicle ablation to induce emergence of a new follicular wave (Day 0 = day of wave emergence, 1 day after ablation) during the non-breeding season. Bison were given FSH diluted in hyaluronan IM on Days 0 (300 mg) and 2 (100 mg), and 2500 IU hCG IM on Day 4. Bison were then assigned randomly to 2 groups (n = 14 per group) in which transvaginal oocyte collection was done at either 30 or 34 h after hCG treatment. The number and size of follicles available for aspiration (i.e. = 5 mm) was compared between groups by Student's t-test. Binomial data (COC collection rate and ovulation rate) were compared by chi-square, and the proportion of cows that ovulated was compared using a Fisher's exact test. Ovulation was defined as the sudden disappearance of follicles ≥10 mm from the hCG treatment to the time of COC collection. The numbers of follicles ≥5 mm and ≥10 mm at the time of COC collection were not different between the 30 and 34 h groups (19.0 ± 1.4 v. 17.4 ± 2.4, and 9.5 ± 1.2 v. 7.7 ± 1.8), nor was the average size of follicles = 5 mm (9.9 ± 0.2 v. 9.8 ± 0.2 mm). The number of follicles aspirated was similar between the 30 and 34 h groups (16.4 ± 1.4 v. 13.4 ± 2.1), but the pre-collection ovulation rate was lower in the 30 h group (12/89 [13.5%] v. 47/147, [32.0%]; P = 0.003), as was the proportion of bison that ovulated (3/14 v. 10/14, P = 0.02). The COC collection rate was lower in the 30 v. 34 h group (64.3% v. 78.2%; P = 0.003), but the total number of COC collected per bison was similar (10.6 ± 1.7 v. 10.5 ± 1.5). Although waiting for 34 h before COC collection resulted in a larger proportion of unwanted ovulations, a greater collection efficiency in the 34 h group resulted in a similar number of COC collected per bison. We conclude that the 30 to 34 h in vivo maturation window provides flexibility for the purposes of oocyte collection and immediate in vitro fertilization in wood bison.We thank Bioniche Animal Health for providing FSH (Folltropin-V) and hyaluronan (MAP-5), and Merck Animal Health for hCG (Chorulon).

171 EXPRESSION OF THE OVULATION-INDUCING FACTOR/NERVE GROWTH FACTOR HIGH AFFINITY RECEPTOR IN THE OVARIES OF COWS DURING THE PERIOVULATORY PERIOD

Ovulation-inducing factor/nerve growth factor (OIF/NGF) influences ovulation and corpus luteum (CL) size and function in camelids and, remarkably, cows. The ovulation effect in induced ovulators is mediated at the hypothalamo-pituitary-axis, but the site and mechanism of action of the luteotrophic effect is unknown. This mechanism may be an important aspect of OIF/NGF in spontaneous-ovulators. The objective of this experiment was to detect changes in expression of the high affinity OIF/NGF receptor (TrkA) in the ovary during the periovulatory period in cattle. Cows (n = 14) were examined daily by transrectal ultrasonography to determine the day of ovulation (Day 0), and were assigned randomly to be unilaterally ovariectomized on Day 2, 4, 6, or in the preovulatory period before or after the LH surge. Cows assigned to preovulatory groups were given a luteolytic dose of prostaglandin when the dominant follicle of the second follicular wave was ≥10 mm and growing. Cows assigned to the pre-LH group were ovariectomized 24 h after prostaglandin treatment. Cows assigned to the post-LH group were given LH 24 h after prostaglandin treatment and were ovariectomized 18–20 h later. Cows were allowed to rest for one complete interovulatory interval and re-assigned to a different day-group on which the remaining ovary was removed (n = 4 to 5 ovaries/day-group). Ovaries were fixed in paraformaldehyde, and 5-μm sections of ovarian tissue representing the dominant follicle, largest subordinate follicle, and the CL were treated for enzymatic antigen retrieval and blocked in 1% BSA for 1 h. Slides were incubated overnight with the primary antibody (rabbit anti-human TrkA) and for 2 h with the secondary antibody (goat anti-rabbit IgG). Slides were evaluated by fluorescence microscopy. Images of 3 arbitrarily chosen fields (40×) were captured for each structure for each day-group, and the average proportion of immunoreactive cells in the theca layer and luteal tissue was estimated using ImageJ software (National Institutes of Health, Bethesda, MD, USA). The intensity of individual cell immunofluorescence was also scored as no reaction (0), faint (1), weak to moderate (2), or strong (3). Data were compared among groups by two-way ANOVA. The proportion of immunoreactive cells was higher in the dominant follicle than in the subordinate follicle or the CL (P < 0.001); no effect of day-group or interaction was detected. The intensity score increased from faint on Day 2 to strong on Day 6, and remained strong in the pre- and post-LH groups. A discernible pattern of change in intensity score was not evident for the subordinate follicle or the CL. The greater proportion of TrkA positive cells and greater immunoreactive intensity in the maturing dominant follicle support the hypothesis that the luteotrophic effect of OIF/NGF in cattle is a result of a local increase in the expression of TrkA in the theca layer of the dominant follicle. Research was supported by the Natural Sciences and Engineering Research Council of Canada.

140 EFFECTIVENESS OF WASHING PROCEDURES FOR REMOVING BRUCELLA ABORTUS FROM IN VIVO-DERIVED WOOD BISON EMBRYOS

Endemic brucellosis threatens wild herds of wood bison (Bison bison athabascae) in and around Wood Buffalo National Park, the largest genetic reserve of wood bison in the world. The overall goal of our project was to produce and preserve disease-free embryos for the purpose of conserving the genetic diversity of this species. The aim of the present experiment was to determine the effectiveness of washing procedures for removing Brucella bacteria from in vivo-derived wood bison embryos exposed in vitro to the pathogen. Wood bison cows were given 300 mg im of Folltropin diluted in 0.5% hyaluronan on the day of follicle wave emergence (Day 0) and 100 mg im of hyaluronan on Day 2, and then given 2500 IU im of hCG on Day 5 and inseminated 12 and 24 h later. Embryos were collected on Day 13. The experiment was done in 6 replicates (n = 4 bison/replicate) and an average of 9 embryos/replicate were collected. Zona pellucida-intact embryos were kept in holding medium (PBS + 2% fetal calf serum) and transported to a Biosafety Level 3 laboratory at the International Vaccine Centre, University of Saskatchewan. Embryos were transferred through 5 aliquots of holding medium to remove any contaminant before exposure to Brucella. Embryos were divided equally into 2 Petri dishes (representing later wash groups with v. without antibiotics) containing 2.7 mL of holding medium (n = 2 to 7 embryos per dish/replicate). In a Class II biosafety cabinet, Brucella abortus biovar 1 (1 × 107 to 1 × 109 CFU mL–1 in 0.3 mL) was added to each Petri dish and incubated for 2 h at 37°C in 8% CO2. A sample of holding medium was taken before exposure and after incubation for culture as negative and positive controls, respectively. After incubation, embryos in each Petri dish were subjected to a 10-step washing procedure (according to the IETS Manual, 2010) using wash medium (PBS + 0.4% BSA) without antibiotics or with antibiotics (100 IU mL–1 of penicillin + 100 μg mL–1 of streptomycin). The embryo wash medium was cultured at wash steps 1, 3, 6, and 9. After the tenth wash, the zona pellucida of each embryo was ruptured mechanically using a glass pipette and embryos were cultured individually. Culturing of samples was done on sheep blood agar and specific identification of Brucella organisms was done by PCR. Brucella abortus was detected in 3 embryos from the group washed in medium without antibiotics (3/27), whereas all embryos washed in medium with antibiotics were culture negative (0/27). Brucella abortus was not detected in wash media after the third wash in either group (with or without antibiotics). In summary, Brucella abortus was removed from 89% of in vitro-exposed wood bison embryos using the washing procedure without antibiotics, and from 100% using the washing procedure with antibiotics. Results validate the embryo washing technique for producing Brucella-free wood bison embryos. Thanks to the Canadian Food Inspection Agency for the field strain of Brucella abortus, Bioniche AH for Folltropin and embryo collection supplies, Merck AH for hCG (Chorulon), and Intervac/VIDO for technical and logistical support.

248 IN VITRO EMBRYO PRODUCTION USING IN VIVO-MATURED OOCYTES COLLECTED TRANSVAGINALLY FROM WOOD BISON (BISON BISON ATHABASCAE)

Reproductive technologies are being developed to help conserve the genetic diversity of wood bison, a threatened species. To date, the efficiency of in vitro embryo production in bison is very low and appears to be related to inadequate in vitro conditions for oocyte maturation. Recently, we have attempted to circumvent the problem by inducing oocyte maturation in vivo and found that more than one-third of superstimulated oocytes collected 30 h after administration of hCG were at metaphase II (Cervantes et al. 2013 Reprod. Fertil. Dev. 25, 283; Cervantes et al. 2014 Reprod. Fertil. Dev. 26, 199). We hypothesise that additional maturation time in vitro, after in vivo maturation, will allow the remaining oocytes to reach the MII stage, and thus improve in vitro embryo production in wood bison. The objective of this study was to determine the effect of an additional 4 h of in vitro maturation on the developmental competence of oocytes collected 30 h after hCG treatment. Wood bison cows (n = 24) were superstimulated by the administration of 300 mg of FSH (Folltropin-V) diluted in 0.05% hyaluronan on the day of follicular wave emergence and 100 mg of FSH in hyaluronan 2 days later. Bison were administered 2500 IU of hCG (Chorulon) IM 2 days after the last dose of FSH. Transvaginal ultrasound-guided follicle aspiration was performed 30 h after hCG treatment to collect cumulus-oocyte complexes (COC). Expanded COC (with no evidence of degeneration) were selected and assigned randomly to 2 groups (n = 38 COC/group) in which IVF was done immediately, or after 4 h of in vitro maturation in TCM 199 with 5% calf serum, 5 μg mL–1 pLH, 0.5 μg mL–1 pFSH, and 0.05 μg mL–1 gentamicin, at 38.5°C, 5% CO2 and high humidity. In vitro fertilization (Day 0) was done with frozen-thawed wood bison semen (dose 5 × 106 sperm mL–1) in Brackett-Oliphant medium at 38.5°C, 5% CO2, and high humidity. Presumptive zygotes were cultured in CR1aa plus 5% calf serum, at 38.5°C and in 5% CO2, 5% O2, and 90% N2 and high humidity. Cleavage was recorded on Day 3, and blastocyst formation was recorded on Days 7 and 8. Cleavage and blastocyst rates (calculated from the total number of oocytes submitted to IVF) were compared between groups by chi-square analysis. No difference was detected between groups (immediate fertilization v. after an additional 4 h in vitro) in cleavage rate on Day 3 (55.3 v. 60.5%, respectively, P = 0.82), or blastocyst rate on Day 7 (13.2 v. 23.7%, respectively, P = 0.37). However, the blastocyst rate on Day 8 was higher in the COC group exposed to an additional 4 h of in vitro maturation (18.4 v. 44.7%, respectively, P = 0.03). Results support the hypothesis that an additional short period of in vitro maturation improves the developmental competence of oocytes collected after 30 h of in vivo maturation.We thank Bioniche Animal Health for providing FSH (Folltropin-V) and hyaluronan (MAP-5), and Merck Animal Health for hCG (Chorulon).

194 EFFECT OF MATERNAL AGE ON THE GRANULOSA CELL TRANSCRIPTOME OF PREOVULATORY FOLLICLES IN CATTLE

The objective was to determine how maternal age influences the transcriptome of the dominant follicle during the preovulatory period. We tested the hypotheses that delayed ovulation in aged cows is associated with 1) altered gene expression of granulosa cells of the preovulatory follicle and 2) decreased synthesis of progesterone by granulosa cells of the preovulatory follicle. Granulosa cells of preovulatory follicles were obtained 24 h after LH treatment from aged Hereford cows (17.0 ± 2.5 years; n = 6) and their daughters (9.0 ± 0.6 years; n = 6), and compared using bovine specific microarrays (EMBV3, EmbryoGENE, Québec, QC, Canada). Results were confirmed by RT-qPCR. A total of 1340 genes or gene isoforms were expressed differentially (≥2-fold change; P ≤ 0.05) in aged cows v. their younger daughters. Differentially expressed up- and down-regulated genes were related to 1) LH response (↑RGS2, ↑SERPINE2, ↑PTGS2), 2) cellular differentiation and luteinization (↑TNFAIP6, ↑GADD45B, ↓VNN1), and 3) progesterone synthesis (↑STAR, ↑HSD3B2, ↑NR5A2, ↑NR4A1). Intra-follicular concentration of progesterone was lower (P < 0.05) in aged v. young cows. Pathway analysis of the dataset revealed that mechanisms of delayed ovulation in aged cows may involve 1) post-receptor desensitization of G-coupled protein receptors, 2) inactivation of tissue plasminogen activator, and 3) delayed production of prostaglandin E2. In conclusion, transcriptome analysis of granulosa cells from aged cows revealed a delayed or suboptimal response to the preovulatory LH stimulus, represented by delayed cellular differentiation, luteinization, and progesterone synthesis. This study was supported by grants from the National Science and Engineering Research Council of Canada, and the EmbryoGene Network, Canada. M.I.R. Khan was supported by graduate assistant scholarship from the Higher Education Commission of Pakistan.

Bioactivity of ovulation inducing factor (or nerve growth factor) in bovine seminal plasma and its effects on ovarian function in cattle

To understand the role of ovulation-inducing factor (or nerve growth factor) (OIF [NGF]) in bovine seminal plasma, we (1) used an in vivo llama bioassay to test the hypothesis that bovine seminal plasma induces ovulation and CL development in llamas similar to that of llama seminal plasma when the dose of seminal plasma is adjusted to ovulation-inducing factor content (experiment 1) and (2) determined the effect of bovine seminal plasma on the interval to ovulation and luteal development in heifers (experiment 2). Within species, seminal plasma was pooled (n = 160 bulls, n = 4 llamas), and the volume of seminal plasma used for treatment was adjusted to a total dose of 250 μg of ovulation-inducing factor. In experiment 1, mature female llamas were assigned randomly to four groups and treated intramuscularly with either 10 mL of PBS (negative control, n = 5), 50-μg GnRH (positive control, n = 5), 6-mL of llama seminal plasma (n = 6), or 12 mL of bull seminal plasma (n = 6). Ovulation and CL development were monitored by transrectal ultrasonography. In experiment 2, beef heifers were given a luteolytic dose of prostaglandin followed by 25-mg porcine LH (pLH) 12 hours later to induce ovulation. Heifers were assigned randomly to three groups and given 12 mL bovine seminal plasma intramuscularly 12 hours after pLH treatment (n = 10), within 4 hours after ovulation (n = 9), or no treatment (control, n = 10). Ovulation was monitored by ultrasonography every 4 hours, and the CL development was monitored daily until the next ovulation. In experiment 1, ovulation was detected in 0/5, 4/5, 4/6, 4/6 llamas in the PBS, GnRH, llama seminal plasma, and bovine seminal plasma groups, respectively (P < 0.05). Luteal development was not different among groups. In experiment 2, the interval to ovulation was more synchronous (range: 4 vs. 22 hours; P < 0.0001) in heifers treated with seminal plasma before ovulation compared with the other groups. Luteal development was not different among groups; however, plasma progesterone concentrations tended to be greater in the postovulation treatment group compared with other groups. In summary, results confirmed the presence of bioactive ovulation-inducing factor in bull seminal plasma and supported the hypothesis that bovine and llama seminal plasma have similar ovulatory effects, using a llama bioassay. Treatment with bovine seminal plasma resulted in greater synchrony of ovulation in heifers pretreated with pLH. Plasma progesterone concentration tended to be higher in heifers given bovine seminal plasma within 4 hours after ovulation, suggesting that bovine ovulation-inducing factor is luteotrophic.

In vivo imaging in the rabbit as a model for the study of ovulation-inducing factors

The study of factors responsible for eliciting ovulation in rabbits has been hampered by the lack of a suitable method of monitoring the ovaries in vivo. Ovarian imaging by ultrasound biomicroscopy was used in two experiments designed to determine the effects of seminal plasma on the ovulatory response in rabbits. In Experiment 1, female rabbits were group-housed and treated intramuscularly with saline, gonadotropin releasing hormone (GnRH), or seminal plasma of llamas or rabbits ( n = 4 to 6 per group). Rabbits were euthanized eight days later to evaluate the ovarian response by ultrasound biomicroscopy ex situ. No differences among groups were detected in the proportion of rabbits that ovulated or in the number and size of corpora lutea. The high incidence of ovulation in the negative control group was unexpected, and confounded determination of an ovulation-inducing effect of seminal plasma. In Experiment 2, female rabbits were caged individually, and treated as in Experiment 1 ( n = 5 to 7 per group). The ovarian response was evaluated in vivo by transcutaneous ultrasound biomicroscopy. Ovulation and formation of corpora lutea were detected only in rabbits given GnRH. A preovulatory surge in plasma luteinizing hormone concentration and a post-ovulatory rise in plasma progesterone concentration were detected only in rabbits treated with GnRH. Surgical translocation of the ovaries to a subcutaneous position enabled longitudinal assessment of the ovulatory response by ultrasound biomicroscopy. Results clearly documented the effect of physical/social interaction on ovulation in rabbits, and did not support the hypothesis that seminal plasma elicits ovulation in rabbits.

Granulosa cell function and oocyte competence: Super-follicles, super-moms and super-stimulation in cattle

The review presents an overview of studies that examined the effects of follicular aging and maternal aging in the bovine model. The first of three main sections is a discussion of the developmental competence of oocytes from (1) the ovulatory follicle of 2-wave and 3-wave estrous cycles, (2) dominant follicles that develop under high or low LH pulse frequency, and (3) natural versus FSH-stimulated ovulatory follicles. The second section highlights the effects of maternal aging. Maternal aging in cattle is associated with (1) elevated circulating FSH concentrations, (2) reduced response to superstimulatory treatment, and (3) markedly decreased early embryonic development in cows >12 year of age. The third and final section on superstimulation protocols addresses the effects of the duration of FSH stimulation and withdrawal (i.e., FSH "starvation" or "coasting") on oocyte competence. Ovarian superstimulation for 4 days altered the expression of genes related to angiogenesis, and activated oxidative stress-response genes. Extending the duration of FSH stimulation from 4 to 7 days resulted in a greater and more synchronous ovulatory response and optimal oocyte maturation. The highest rates of blastocyst development in vitro were obtained when FSH support was discontinued for 44 to 68h and granulosa cell SMAD7 mRNA was predictive of this period. Longer periods of FSH starvation resulted in a loss of oocyte competence or ovulatory capability. By extending the bovine model to the transcriptome level, new approaches and treatments may be devised to resolve subfertility in women and animals.

171 IN VIVO AND IN VITRO MATURATION OF WOOD BISON (BISON BISON ATHABASCAE) CUMULUS–OOCYTE COMPLEXES DURING THE OVULATORY SEASON

Technologies are being developed to conserve the genetic diversity of wood bison. Knowledge of the characteristics of in vivo and in vitro maturation of the cumulus–oocyte complex (COC) are needed in wood bison to design efficient in vitro embryo production protocols. The objectives were to (1) determine the optimal interval after hCG treatment for in vivo maturation of COC in superstimulated wood bison, and (2) compare the characteristics of COC after in vitro and in vivo maturation. Ovarian synchronization was induced in 25 bison during October and November by giving a luteolytic dose of prostaglandin followed 8 days later by follicular ablation (Day –1). Ovarian superstimulation was induced with FSH (Folltropin-V) given i.m. on Day 0 (300 mg) and Day 2 (100 mg). A second luteolytic dose of prostaglandin was given on Day 3. Bison were assigned randomly to 5 groups (n = 5/group). The COC were collected by transvaginal follicle aspiration on Day 4 and were either assessed immediately (0 h, control), or matured in vitro for 24 or 30 h (in vitro maturation), or collected on Day 5 (in vivo maturation), 24 or 30 h after bison were given 2000 IU of hCG i.m. on Day 4. In vitro maturation was done in TCM-199 with 5% calf serum, 5 μg mL–1 LH, 0.5 μg mL–1 FSH, and 0.05 μg mL–1 gentamicin, at 38.5°C and in a 5% CO2 humidified atmosphere. Nuclear maturation was classified as germinal vesicle (GV), germinal vesicle breakdown (GVBD), metaphase I (MI), or metaphase II (MII) with anti-lamin AC/DAPI staining. Groups were compared by analysis of variance and Fisher's exact test (Table 1). A mean (±s.e.m.) of 7.3 ± 1.7 COC were collected per bison, with no difference among groups. The COC in the control (0 h) group were at the nonexpanded GV stage. Cumulus cells were more expanded after in vivo than in vitro maturation, and the percentage of fully expanded COC was the highest in the 30-h in vivo maturation group (87%; P < 0.05). The greatest number of oocytes reached MII stage after 24 h of in vitro maturation, and 30 h of in vivo maturation. In conclusion, nuclear maturation occurred more quickly in vitro compared with in vivo, but the degree and incidence of cumulus expansion was greater after in vivo maturation. The competence of oocytes to undergo fertilization and develop into embryos remains to be investigated. Table 1.Cumulus expansion and nuclear maturation of wood bison oocytes

Effect of vehicle and route of administration of letrozole on ovarian function in a bovine model

The objective of this study was to determine the effects of vehicle and route of administration of letrozole on ovarian function in sexually mature beef heifers. On Day 3 (Day 0 = ovulation), heifers were assigned randomly to four treatment groups and given 1 mg kg–1 letrozole intravenously (iv, n = 10) or intramuscularly (im, n = 10) or given a placebo iv (control iv, n = 5) or im (control im, n = 5). The interwave interval was longer in heifers treated with letrozole im than in im and iv controls (11.7 ± 0.30 vs 9.5 ± 0.50 and 10 ± 0.43, respectively; P < 0.05). Corpus luteum diameter profiles and plasma progesterone concentrations were greater (P < 0.03 and P < 0.05, respectively) in heifers treated with letrozole im compared with control im. Plasma oestradiol concentrations were lower in both letrozole-treated groups compared with controls (P ≤ 0.03). Plasma LH concentrations tended to be elevated at the time of wave emergence in heifers treated with letrozole im compared with other groups (group-by-day interaction, P = 0.06) and plasma FSH concentrations tended to be greater (P < 0.09) in heifers treated with letrozole by either route compared with a single control group. We conclude that intramuscular administration of letrozole in oil is a feasible route and vehicle for the development of a letrozole-based treatment protocol for herd synchronisation in cattle.

Ultrasound biomicroscopy: a non-invasive approach for in vivo evaluation of oocytes and small antral follicles in mammals

The use of ultrasonography has changed our understanding of the ovarian function in live animals. However, most of the studies that have used ultrasonography to image the ovary have provided data only of structures >1 mm in diameter. The recent availability of high-resolution ultrasound technology with high-frequency transducers (25–70 MHz), offers the potential to examine the developmental dynamics of small antral follicles and the cumulus–oocyte complex (COC) in vivo. In this review we provide data from a series of studies performed by Veterinary Biomedical Sciences Laboratory describing the advantages and disadvantages, as well as image characteristics, of ultrasound biomicroscopy (UBM) to study ovarian biology in mammals. Data and images of small ovarian structures in rabbits, cattle, mice and humans are shown. The UBM technique allowed visualisation of small antral follicles ranging in size from 300 to 700 μm in all species examined, as well as COC within follicles in rabbits, cattle and humans. Furthermore, UBM permitted clear distinction of the follicular wall from the surrounding ovarian stroma in cattle and humans. At present, the limited depth of penetration of UBM restricts the use of this technique to an experimental setting. In that regard, further studies using UBM will probably result in a greater understanding of the pattern and control of early antral folliculogenesis and oogenesis.

212 EFFECT OF A LOW DOSE OF eCG ON SUPEROVULATION AND EMBRYO COLLECTION IN WOOD BISON DURING THE BREEDING SEASON

In an effort to conserve a threatened Canadian species, Bison bison athabascae, we developed an embryo collection protocol subsequent to superovulatory treatment involving two doses of FSH diluted in hyaluronan given 48 h apart. The follicular response to superstimulatory treatment was satisfactory, but many follicles did not ovulate, thus limiting the number of embryos collected. Based on recent results in cattle, where replacement of the final doses of FSH with a low dose of eCG resulted in the recovery of a greater number of ova/embryos, the objective of the present study was to evaluate the effect of adding eCG to the superovulatory protocol to increase ovulation rate, embryo collection, and embryo quality in wood bison during the breeding season (September). Ovarian synchronization was induced in wood bison (n = 24) by treatment with a luteolytic dose of prostaglandin (500 mcg, Cloprostenol) followed 8 days later by transvaginal ultrasound-guided follicular ablation. Follicular wave emergence (Day 0) was defined as the day after follicle ablation. Bison were assigned randomly to two groups: FSH (n = 12) and FSH+eCG (n = 12). FSH was diluted in hyaluronan (5 mg mL–1, MAP-5, Bioniche Animal Health, Belleville, ON, Canada) and given intramuscularly on Day 0 (300 mg) and Day 2 (100 mg) in both groups. Bison in the FSH+eCG group received 450 IU eCG (Pregnecol, Bioniche Animal Health) intramuscularly on Day 3, and bison in both groups were administered a luteolytic dose of prostaglandin on Day 3. On Day 5, bison were given 2500 IU hCG (Chorulon, Merck Animal Health, Summit, NJ, USA) intramuscularly to induce ovulation. The bison were artificially inseminated with chilled semen 12 and 24 h after hCG treatment. Nonsurgical embryo collection was performed on Day 13. The ovaries were examined by transrectal ultrasonography on Days 5, 7, and 13 to record the follicular response, ovulation rate, and number of corpora lutea (CL), respectively. Results were compared between groups by t-test or chi-square test (Table 1). The number of ovulatory-sized follicles (≥9 mm), ovulation rate (number ovulations/ovulatory-sized follicles), number of CL, number of ova/embryos, and number of transferable embryos were not different between groups (P = 0.23, P = 0.19, P = 0.25, P = 0.18, P = 0.09, respectively). In conclusion, the superovulatory response and embryo collection rate in wood bison approached that observed in cattle, but were not improved by the addition of a low dose of eCG. Table 1.Response of wood bison (mean ± s.e.m.) to superovulatory treatment with or without eCG

Differential gene expression of granulosa cells after ovarian superstimulation in beef cattle

Microarray analysis was used to compare the gene expression of granulosa cells from dominant follicles with that of those after superstimulatory treatment. Cows were allocated randomly to two groups (superstimulation and control, n=6/group). A new follicular wave was induced by ablation of follicles ≥5 mm in diameter, and a progesterone-releasing device controlled internal drug release (CIDR) was placed in the vagina. The superstimulation group was given eight doses of 25 mg FSH at 12-h intervals starting from the day of wave emergence (day 0), whereas the control group was not given FSH treatment. Both groups were given prostaglandin F2α twice, 12 h apart, on day 3 and the CIDR was removed at the second injection; 25 mg porcine luteinizing hormone (pLH) was given 24 h after CIDR removal, and cows were ovariectomized 24 h later. Granulosa cells were collected for RNA extraction, amplification, and microarray hybridization. A total of 190 genes were downregulated and 280 genes were upregulated. To validate the microarray results, five genes were selected for real-time PCR (NTS, FOS, THBS1, FN1, and IGF2). Expression of four genes increased significantly in the three different animals tested (NTS, FOS, THBS1, and FN1). The upregulated genes are related to matrix remodeling (i.e. tissue proliferation), disturbance of angiogenesis, apoptosis, and oxidative stress response. We conclude that superstimulation treatment i) results in granulosa cells that lag behind in maturation and differentiation (most of the upregulated genes are markers of the follicular growth stage), ii) activates genes involved with the NFE2L2 oxidative stress response and endoplasmic reticulum stress response, and iii) disturbs angiogenesis.

Effect of duration of the growing phase of ovulatory follicles on oocyte competence in superstimulated cattle

In the present study, we tested the hypotheses that oocyte competence is compromised by a longer duration of follicular growth and that it is not affected by FSH starvation. Cows were allocated to short FSH (n=14), FSH starvation (n=13) and long FSH (n=13) groups. The first two groups were given eight doses of FSH, whereas the third group was given 14 doses of FSH, starting from the day of wave emergence (Day 0). A progesterone-releasing device (controlled internal drug release; CIDR) was placed intravaginally at the start of the experiment in all groups. The short FSH group was given prostaglandin (PG) F2α on Day 3, whereas the two other groups received PGF2α on Day 6. In all cows, the CIDR was removed at the time of PGF treatment; porcine (p) LH was given 24h after CIDR removal and cows were inseminated 24 and 36h later. Reproductive tracts were collected 4 days after insemination and ova and/or embryos were cultured for ≥6 days. The FSH starvation group had fewer ovulations (P=0.001), and ova and/or embryos (P&lt;0.05). No difference in embryo quality was detected between long and short FSH groups at 7, 9 or 10 days after artificial insemination. In conclusion, oocyte competence was not altered by the duration of the follicular growth phase in superstimulated cows, whereas FSH starvation substantially reduced the ability of superstimulated follicles to ovulate.

2 TRANSCRIPTOME ANALYSIS OF GRANULOSA CELLS FROM GROWING DOMINANT FOLLICLE REVEALS AGE-ASSOCIATED CHANGES AT THE TIME OF FOLLICLE SELECTION IN AGED BEEF CATTLE

Growing dominant follicles at the time of selection from aged (n = 3; 15 ± 1.5 years) and young (n = 3; 6 ± 1.1 years) Hereford cows were compared using bovine-specific microarrays containing 40 000 targets. The objective of the study was to determine age-associated changes in transcriptome of granulosa cells at the time of dominant follicle selection. Cows were given prostaglandin F2α to cause ovulation (Day 0) and granulosa cells from dominant follicles were collected on Day 3 either by ultrasound-guided follicle aspiration or after ovariectomy. The mRNA was extracted, analyzed for quality, converted into antisense RNA, amplified, labelled with red and green florescent dyes, and hybridized with microarrays. Feature intensities were measured using Array-Pro software (Media Cybernetics Inc., Rockville, MD), and differentially expressed genes were obtained using FlexArray 1.6. A total of 169 transcripts were differentially expressed with a fold change of ≥2 (P ≤ 0.05) in aged cows v. young cows. Ingenuity System Pathway (IPA; Ingenuity Systems Inc., Redwood City, CA) analysis of these transcripts revealed that granulosa cells of aged cows exhibit (1) reduced capability to regulate gonadotropins [↓follistatin (FST), ↓inhibin beta A (INHBA), ↓inhibin beta B (INHBB)] and reduced responsiveness to gonadotropin-induced changes in cytoskeleton [↑tropomyosin 2 (TPM2), ↑actin gamma 2 (ACTG2), ↓tubulin beta] and extracellular matrix [↓tumor necrosis factor alpha-induced protein 6 (TNFAIP6), ↓versican (VCAN)], (2) inefficiency in processing lipids [↓low-density lipoprotein receptor (LDLR), ↓stearoyl-coenzyme A desaturase (SCD), ↑cluster of differentiation 36 (CD36), ↓sterol-C4-methyl oxidase-like (SC4MOL)] and synthesizing steroids [↓cytochrome P450, family 19, subfamily A, polypeptide 1 (CYP19A1), ↓cytochrome P450, family 51, subfamily A, polypeptide 1 (CYP51A1)], (3) decreased proliferation [↓proliferating cell nuclear antigen (PCNA)] and control of cell cycle check points [↓checkpoint kinase 1 (CHEK1), ↓centromere-associated protein E (CENPE)] and have poor intercellular communication [↓gap junction protein alpha 1 (GJA1)], and (4) higher expression of oxidative stress responsive genes [↑vanin-1 (VNN1), ↑vanin-2 (VNN2), and ↑glutathione peroxidase 3 (GPX3)]. A total of 6 transcripts: CYP19A1 (aromatase; P ≤ 0.1), VNN1 (P ≤ 0.05), INHBA (P ≥ 0.1), PCNA (P ≤ 0.001), TPM2 (P ≤ 0.1), and GJA1 (P ≤ 0.05) were selected to validate the microarray results via quantitative real-time PCR. In conclusion, granulosa cells of growing dominant follicles exhibit age-related changes in the transcriptome at the time of selection relative to young cows; changes that may explain follicle-associated loss of oocyte competence in aged cows. Research was supported by the Natural Sciences and Engineering Research Council of Canada (Ottawa, ON, Canada).

310 DOES PROGESTERONE OR EQUINE CHORIONIC GONADOTROPIN IMPROVE THE SUPEROVULATORY RESPONSE AND EMBRYO QUALITY IN WOOD BISON DURING THE ANOVULATORY SEASON?

Superovulation protocols are being developed in wood bison (Bison bison athabascae), a threatened Canadian species. In initial studies, 2 doses of FSH diluted in hyaluronan given 48 h apart were successful for inducing ovarian superstimulation in wood bison, and ovulation rate was improved by final treatment with hCG instead of LH (Palomino et al. 2012 Reprod. Fertil. Dev. 24, 226). In that study, exogenous progesterone had no effect on the number of ovulations, but embryo quality could not be evaluated because of the low number of embryos collected. In beef cattle, replacement of the final doses of FSH with eCG has resulted in the recovery of a greater number of ova/embryos. The objective of the present study was to evaluate the effect of exogenous progesterone (PRID) on embryo quality and to determine if the addition of eCG increases the ovulation rate in superstimulated wood bison. Follicular ablation was done to synchronize follicular wave emergence in 26 wood bison cows during the anovulatory season (May). Cows were assigned randomly to 3 groups: PRID/no eCG (n = 8), PRID/eCG (n = 9), and no PRID/eCG (n = 9). A PRID was inserted on the day of follicular ablation (Day –1) in respective groups. In all bison, FSH diluted in hyaluronan (5 mg mL–1, MAP-5, Bioniche Animal Health Inc., Belleville, Ontario, Canada) was given intramuscularly on Day 0 (300 mg) and Day 2 (100 mg). On Day 3, a single dose of 450 IU of eCG (Pregnecol, Bioniche Animal Health Inc.) was given intramuscularly and the PRID were removed in the corresponding groups. On Day 5, all bison were given 2500 IU of hCG (Chorulon, Merck, Whitehouse Station, NJ, USA) intramuscularly to induce ovulation. Bison were inseminated with chilled semen 12 and 24 h later. Nonsurgical embryo collection was performed on Day 14. Transrectal ultrasonography was done to record the ovarian response, ovulation rate, and number of corpora lutea (CL). Results were compared by ANOVA and Chi-squared test (Table 1). The number of ovulatory-sized follicles (≥9 mm) on Day 5 did not differ among groups. Ovulation rate was lowest in bison treated with both a PRID and eCG (P < 0.05). There were no differences among groups in the number of CL on Day 14, the number of ova/embryos collected, or the number of transferable embryos. The superovulatory response and embryo collection rate in the present study were higher than in any previous reports in bison. The ovulation rate was not improved by the addition of eCG treatment, and exogenous progesterone had no effect on embryo quality. Table 1.Response of superstimulated wood bison (mean ± SEM) to treatment with exogenous progesterone (PRID) and/or eCG

313 EFFECT OF DURATION OF THE GROWING PHASE OF OVULATORY FOLLICLES IN SUPERSTIMULATED HEIFERS ON OOCYTE COMPETENCE AFTER IN VITRO FERTILIZATION

We tested the hypotheses that extending the duration of follicular growth by superstimulation increases oocyte competence, and that FSH starvation at the end of superstimulatory treatment decreases oocyte competence. Heifers were allocated randomly to short FSH duration (n = 8), FSH starvation (n = 8), or long FSH duration (n = 8) groups. Five to 8 days after ovulation, transvaginal ultrasound-guided follicle ablation was done to synchronize follicle wave emergence, and a progesterone-releasing device (CIDR; Pfizer Animal Health, New York, NY, USA) was placed intravaginally. Short FSH and FSH starvation groups were given 8 doses of FSH (Folltropin-V; Bioniche Animal Health Inc., Belleville, ON, Canada) IM, whereas the long FSH group was given 14 doses of FSH at 12-h intervals, starting from the day of wave emergence (Day 0). Prostaglandin F2α (PGF) was administered twice, 12 h apart, on Day 3 in the short FSH group and on Day 6 in the other 2 groups. In all heifers, the CIDR was removed at the time of the second PGF treatment; pLH (Lutropin-V; Bioniche Animal Health Inc.) was given IM 24 h after CIDR removal, and cumulus–oocyte complexes (COC) were collected 24 h after pLH treatment. The COC were matured in vitro (6 h) and fertilized (IVF), and the embryos were cultured for 10 days. At 12 h after pLH, the long FSH group had a greater number of ≥9 mm follicles than the FSH starvation and short FSH groups (25.4 ± 5.3 v. 11.0 ± 2.1 and 10.6 ± 2.3, respectively; P < 0.03). The long FSH group also had more expanded COC than the FSH starvation group (P < 0.001), but did not differ from the short FSH group (93, 54, and 74%, respectively). The FSH starvation group had a greater proportion (P < 0.0001) of partially expanded COC (32%) and poor quality oocytes (70%) than did the long (1 and 33%) and short (4 and 45%) FSH groups; oocyte quality did not differ between long and short FSH groups. At 48 h after IVF, the cleavage rate was lower in the FSH starvation group compared with the short and long FSH groups (35, 54, and 56%, respectively; P = 0.003). After 9 days in culture, embryo development (morula + blastocyst) in the FSH starvation group was lower than that in the long FSH group, (18 v. 37%; P = 0.04), but did not differ from that in the short FSH group (25%). After removal of the data of one heifer in the FSH starvation group that produced 52% of total embryos in that group (outlier), the Day 9 blastocyst rate was lower in the FSH starvation group than in the short and long FSH groups (2% v. 14 and 21%, respectively; P = 0.02). In conclusion, extending the standard superstimulation protocol by 3 days enhanced ovarian response to FSH treatment, but did not improve oocyte competence, whereas a period of FSH starvation after FSH treatment compromised oocyte quality and embryo development.

271 NUCLEAR MATURATION OF WOOD BISON (BISON BISON ATHABASCAE) CUMULUS - OOCYTE COMPLEXES

Methods of producing wood bison embryos in vivo and in vitro are being developed in an effort to preserve the genetic diversity of this threatened species. Previous data from our laboratory suggest that oocytes collected 24 h after LH treatment had not yet achieved nuclear maturation. The objectives of this study were (1) to determine the optimal interval of time after hCG treatment required for in vivo maturation of cumulus–oocyte complexes (COC) in wood bison, and (2) to compare the maturational characteristics of COC after in vitro v. in vivo maturation. Follicular wave emergence was synchronized among bison cows (n = 25) by follicular ablation (Day –1) from May to June. Ovarian superstimulation was induced with FSH IM diluted in 5 mg mL–1 of hyaluronan (MAP-5, Bioniche, Belleville, Ontario, Canada) given on Day 0 (300 mg) and Day 2 (100 mg). Superstimulated cows were assigned randomly to 5 groups (n = 5/group): COC collected on Day 4 with no maturation (control), or matured in vitro for 24 or 30 h, or collected 24 or 30 h after treatment with 2000 IU of hCG IM on Day 4. The COC were collected by transvaginal ultrasound-guided follicle aspiration. In vitro maturation was done in TCM-199 with 5% calf serum, 5 µg mL–1 of LH, 0.5 µg mL–1 of FSH, and 0.05 µg mL–1 of gentamicin, at 38.5°C and in 5% CO2. To assess nuclear maturation, oocytes were stained with anti-lamin AC/DAPI (4′,6-diamidino-2-phenylindole). Nuclear stages were classified as germinal vesicle (GV), GV breakdown (GVBD), metaphase I (MI), or metaphase II (MII). Comparisons among groups were made by ANOVA and Fisher’s exact test (Table 1). A mean (± SEM) of 7.6 ± 0.6 COC was collected per bison; no differences were observed among groups (P = 0.37). Cumulus cell expansion was more extensive after in vivo than in vitro maturation, and the percentage of fully expanded COC was highest in the in vivo 30-h group (97%; P < 0.05). No COC were expanded in the control (0 h) group, and none reached MI. Maximal nuclear maturation was achieved in vitro by 24 h; that is, there was no difference in the proportion of MII-stage COC at 24 versus 30 h. However, between 24 and 30 h of in vivo maturation, the percentage of nuclear stages GV + GVBD decreased from 54 to 24% (P < 0.05), whereas nuclear stages MI + MII increased from 39 to 74% (P < 0.05). In conclusion, nuclear maturation occurred earlier in vitro versus in vivo, but the consequences of this difference are unknown. Although more than one-third of oocytes matured in vivo for 30 h were mature enough to permit immediate IVF, whether additional in vivo maturation time would be beneficial to fertilization rates remains to be tested. Table 1.Nuclear status of wood bison oocytes after in vitro or in vivo maturation Thanks to Bioniche Canada.

182 EFFECT OF OVULATION-INDUCING FACTOR ON DEVELOPMENT AND VASCULAR PERFUSION OF THE OVULATORY FOLLICLE AND CORPUS LUTEUM IN LLAMAS

The aim of the study was to determine if purified ovulation-inducing factor (OIF) from llama seminal plasma evokes changes in tissue vascular area of the preovulatory follicle and CL. Mature non-lactating, non-pregnant, female llamas (n = 20) were monitored by transrectal ultrasonography using a 7.5-MHz linear-array transducer (MyLab 5, Canadian Veterinary Imaging) to determine ovarian follicular status. Llamas with a growing follicle (for 3 consecutive days) ≥8 mm were assigned randomly to 2 groups (n = 10/group) and given an i.m. dose of (1) 50 µg of gonadorelin acetate or (2) 1 mg of purified OIF from llama seminal plasma. Llamas were examined daily by transrectal ultrasonography using B-mode and power Doppler mode from Day 0 (day of treatment) to Day 16 to detect ovulation and CL development, and to calculate the area of blood-flow signal in the preovulatory follicle at 12 h after treatment and in the CL on Days 2, 4, 6, 8, 10, 12, 14, and 16. Power Doppler images were recorded, edited, and analysed using the ImageJ software (National Institutes of Health, Bethesda, MD, USA). Data were compared between groups by Student t-test, chi-square, and ANOVA for repeated measures. No differences were detected between GnRH and OIF groups, respectively, in the diameter of the preovulatory follicle at the time of treatment (9.7 ± 0.3 v. 9.9 ± 0.4 mm), ovulation rate (10/10 v. 10/10), interval from treatment to ovulation (32.0 ± 0.6 v. 30.4 ± 1.8 h), maximum CL diameter (13.05 ± 0.4 v. 13.5 ± 0.3 mm), or the day on which the CL reached the maximum diameter (8.7 ± 0.3 v. 8.2 ± 0.2). The preovulatory follicle from llamas treated with purified OIF had a greater (P ≤ 0.0001) blood-flow signal area after treatment than that of the GnRH group. Similarly, the luteal tissue of llamas treated with purified OIF had a greater (P ≤ 0.001) blood-flow signal area than that of the GnRH group on Days 4, 6, 12, and 16 after treatment. We conclude that OIF purified from llama seminal plasma increases the vascular perfusion of the preovulatory follicle and the subsequent CL, consistent with the hypothesis that OIF is luteotrophic. Research funded by Chilean National Science and Technology Research Council (Fondecyt Regular 1120518), the Natural Sciences and Engineering Research Council of Canada, and the Alpaca Research Foundation.

174 ULTRASOUND BIOMICROSCOPIC IMAGE ATTRIBUTES OF OVARIAN FOLLICLES IN HEIFERS

High-resolution ultrasound biomicroscopy (UBM) with high-frequency transducers (20 to 50 MHz) has enabled imaging of small antral follicles (<1 mm) and acoustic characterisation of the follicular antrum and wall. Quantitative echotextural analysis of the images generated by UBM provides detailed functional information about the granulosa and theca layers of follicle walls. The objectives of our study were to compare biomicroscope image echotextures between dominant and largest subordinate follicles during the first follicular wave and to characterise UBM attributes of the ovulatory follicle. Hereford crossbred heifers (14 to 16 months old, n = 12) were used. Ovarian examinations were performed transvaginally from Day –4 or –3 (Day 0 = ovulation) to Day 10 using a UBM imaging instrument (Vevo 660; Visual Sonics Inc., Toronto, Canada) equipped with a 25-MHz end-fire transducer. Echotextural assessment was performed by spot metrics of the follicle antrum and follicle wall by using a series of custom-developed computer algorithms optimized for ultrasonography (Synergyne©, Version 2.8, WHIRL, Saskatoon, SK, Canada). Although subordinate and dominant follicles development were tracked from Day –2 (around 1 mm in diameter) to Day 10, the ovulatory follicle was tracked only from Day –4 to ovulation. All data were analysed by analysis of variance for repeated measures using the Mixed procedure (Littell et al. 1998) in the Statistical Analysis System software package (SAS version 8.2 for MS Windows; SAS Institute Inc., Cary, NC, USA). No differences were detected between dominant and largest subordinate follicle in the mean pixel value (MPV) or pixel heterogeneity (PH) of the antrum. However, the MPV of the wall of dominant follicles was greater and PH tended to be greater than that of the largest subordinate follicles (P = 0.05 and P = 0.1, respectively). This result could be evidence that the dominant follicle would be healthier. The PH of the wall the ovulatory follicle decreased (P = 0.03) from Day –4 to Day –1; however, no changes in MPV were observed. Similarly, no changes were detected in MPV or PH of the follicular antrum. The loss of granulosa cells from the follicular wall can explain, at least in part, the decrease in mean pixel value and pixel heterogeneity of the follicular wall detected in ovulatory follicles. Moreover, morphologic changes indicative of atresia are typically represented by high values of number of pixel values. In conclusion, although no differences in antral characteristics of dominant v. subordinate follicles were detected, mean pixel value and pixel heterogeneity of the follicular wall were higher in dominant follicles, and pixel heterogeneity of follicular wall of ovulatory follicles decreased over days. Quantitative pixel analysis from follicular wall images using UBM could be applied to evaluate follicles in live animals. However, more studies using this technique are necessary. Research was supported by NSERC and CIHR. Luiz Pfeifer was supported by CAPES from Ministry of Education, Brazil.

107 DETECTION OF BIOTINYLATED-OVULATION-INDUCING FACTOR (OIF) IN CEREBROSPINAL FLUID AND ITS ABILITY TO INDUCE OVULATION

Ovulation-inducing factor (OIF) is a protein in the seminal plasma of llamas that induces a preovulatory LH surge by acting directly or indirectly on the hypothalamic GnRH neurons (Silva et al. 2011 Reprod. Biol. Endocr. 9, 74). We hypothesize that OIF crosses the blood–brain barrier and reaches the hypothalamus via secretion into the cerebro-spinal fluid (CSF) through the choroid plexus. Two experiments were designed to determine whether biotinylation of OIF (as a tracer) alters its bioactivity in a llama model (Experiment 1) and whether it crosses the blood–brain barrier in a rabbit model (Experiment 2). In Experiment 1, llamas with a follicle ≥8 mm in diameter that had grown for 3 consecutive days were assigned randomly to 5 groups (n = 2/group) and given an IV dose of 1) 800 µg of OIF, 2) 800 µg of OIF biotinylated at the amino end; 3) 1600 µg of OIF biotinylated at the amino end, 4) 800 µg of OIF biotinylated at the carboxyl end, or 5) phosphate buffered saline (control). The ovaries were examined daily by transrectal ultrasonography on Day 3 and 8 after treatment (Day 0 = treatment) to detect ovulation and corpus luteum formation. In Experiment 2, adult female rabbits were assigned randomly to 3 groups and given an IV dose of (1) 250 µg of OIF, (2) 250 µg of OIF biotinylated at the amino end, or (3) 250 µg of OIF biotinylated at the carboxyl end. A 50-µL sample of CSF was collected from the cisterna magna under general anesthesia before (0 min) and 10, 20, 30, and 45 min after treatment. The presence of biotinylated OIF in CSF samples was determined by dot blot, using streptavidin-peroxidase and diaminobenzidine. In Experiment 1, the diameter of the follicle at the time of the treatment did not differ among groups (9.7 ± 0.2, 9.4 ± 0.0, 10.5 ± 1.0, 10.1 ± 0.2, 10.3 ± 0.4). Ovulation was detected in all llamas except one llama treated with 800 µg OIF biotinylated at the carboxyl end and both llamas given PBS. The diameter of the corpus luteum did not differ among OIF-treated groups. In Experiment 2, OIF biotinylated at both amino and carboxyl ends was detected in CSF samples at 10, 20, 30, and 45 min after IV administration. No signal was recorded before IV administration (0 min) or in samples from rabbits that were given nonbiotinylated OIF. We conclude that the biotinylation process did not affect OIF bioactivity, and OIF crosses the blood–brain barrier and reaches the CSF in rabbits. Research supported by FONDECYT 1120518, the Natural Sciences and Engineering Research Council of Canada, and the Alpaca Research Foundation.