Global transcriptomic response of bovine endometrium to blastocyst-stage embryos

The aims of this study were (i) to investigate changes in the global transcriptome of bovine endometrial explants induced by exposure to blastocysts, (ii) to investigate if male and female blastocysts elicit a differential response in the endometrial transcriptome in vitro and (iii) to determine whether bovine endometrium responds to the presence of murine embryos. In Experiment 1, endometrial explants from the same uterus were cultured for 6 h with or without 20 in vitro-produced bovine blastocysts. In Experiment 2, endometrial explants were cultured with male or female bovine blastocysts produced in vitro by IVF either using sex-sorted semen or conventional unsorted semen followed by embryo sexing based on a biopsy. In Experiment 3, endometrial explants were cultured alone or in the presence of bovine blastocysts (n = 25) or murine blastocysts (n = 25). Following culture, explants were snap frozen and stored at -80°C until RNA extraction, qPCR or RNA-Seq. Culture with bovine blastocysts increased endometrial expression of 40 transcripts, all of which were interferon-tau induced. Culture with male or female bovine blastocysts increased transcript abundance of five classic interferon-stimulated genes (MX1, MX2, ISG15, OASY1, RSAD2) in explants; however, there was no difference in abundance of transcripts previously reported to be related to embryonic sex (IFNAR1, IFNAR2, CTGF, ARTN, SLC2A1, SLC2A5). Exposure to murine blastocysts did not elicit any detectable change in transcript abundance. These findings, coupled with our previous data, indicate that very local, interferon-tau-induced changes in endometrial gene expression occur in response to blastocysts; whether such changes play any role in subsequent pregnancy recognition remains to be established.

Blastocyst-induced changes in the bovine endometrial transcriptome

The objectives of this study were (i) to determine whether blastocyst-induced responses in endometrial explants were detectable after 6- or 24-h co-culture in vitro; (ii) to test if direct contact is required between embryos and the endometrial surface in order to stimulate endometrial gene expression; (iii) to establish the number of blastocysts required to elicit a detectable endometrial response; (iv) to investigate if upregulation of five interferon-stimulated genes (ISGs) in the endometrium was specific to the blastocyst stage and (v) to test if alterations in endometrial gene expression can be induced by blastocyst-conditioned medium. Exposure of endometrial explants to Day 8 blastocysts in vitro for 6 or 24 h induced the expression of ISGs (MX1, MX2, OAS1, ISG15, RSAD2); expression of IFNAR1, IFNAR2, NFKB1, IL1B, STAT1, LGALS3BP, LGALS9, HPGD, PTGES, ITGB1, AKR1C4, AMD1 and AQP4 was not affected. Culture of explants in the presence of more than five blastocysts was sufficient to induce the effect, with maximum expression of ISGs occurring in the presence of 20 blastocysts. This effect was exclusive to blastocyst stage embryos; oocytes, 2-cell embryos or Day 5 morulae did not alter the relative abundance of any of the transcripts examined. Direct contact between blastocysts and the endometrial surface was not required in order to alter the abundance of these transcripts and blastocyst-conditioned medium alone was sufficient to stimulate a response. Results support the notion that local embryo-maternal interaction may occur as early as Day 8 of pregnancy in cattle.

Investigation of in vitro measurable sperm attributes and their influence on electroejaculated bull semen with a fixed-time artificial insemination protocol in Australian Bos indicus cattle

Increasing use of fixed-time artificial insemination (FTAI) in beef cattle production has presented an opportunity for the use of fresh or chilled semen as an alternative to standard cryopreserved semen. The objective of this study was to examine in vitro sperm function and pregnancy rate of electroejaculated semen, chilled and stored for 48 hr, compared to conventionally cryopreserved semen with an optimized FTAI protocol in Brahman cattle. Semen from three Brahman bulls was collected, and aliquots were extended in either chilled (at 5°C) or frozen (LN₂ ) in a Tris-egg yolk extender base with 2.4% or 7.0% glycerol, respectively. Semen samples were assessed 48 hr after collection or post-thaw and warming, for sperm motility, in vitro sperm function and fertilizing ability, and used in a FTAI programme. The overall pregnancy rates was significantly different (p < .01) after FTAI with frozen (n = 173; 53.2%) and chilled semen (n = 174; 31.6%). In contrast, the in vitro sperm assessment showed that the chilled semen had significantly faster motility (p < .05), a higher proportion of progressively motile spermatozoa (p < .05), with significantly higher proportions of acrosome intact, viable spermatozoa (p < .01). This study showed that reasonable pregnancy rates in Brahman cattle can be achieved using FTAI with chilled semen collected using electroejaculation and stored for up to 48 hr. However, improvements in semen extenders are required in consideration of semen collection method to improve the longevity of sperm fertilizing ability to significantly increase FTAI output using chilled storage of bull semen.

Development of a GnRH-PGF2α-progesterone-based synchronization protocol with eCG for inducing single and double ovulations in beef cattle

Experiments were designed to investigate the effect of different doses and timing of an eCG treatment given during GnRH-based synchronization protocols on follicular dynamics and fertility in cattle. In Exp. 1, Angus heifers (n = 50) received a 7-d Ovsynch + progesterone protocol (on d 0, GnRH and progesterone insert were administered; on d 7, progesterone insert was removed and PGF2α was injected; and on d 9.5, GnRH was injected 56 h after progesterone removal) with eCG (0, 300, 500, 700, or 1,000 IU) administered on d 7. In Exp. 2, Angus cows (n = 27) received the same protocol as Exp. 1 and were assigned randomly to receive 0 or 400 IU eCG i.m. on d 2 or 7. In Exp. 3, Angus cows (n = 18) received a 6-d Ovsynch + progesterone protocol and were randomly assigned to receive 0 or 800 IU eCG on d 3 of the protocol (Exp. 3a). A pilot field trial was also performed using the same treatments in suckled Angus-cross cows (n = 72; Exp. 3b). In Exp. 4, beef heifers (n = 200) were assigned randomly to the same treatments as in Exp. 3, but the second GnRH was not given, with Holstein bulls introduced on d 6. In Exp. 5, Angus cows (n = 12) received the same treatment as in Exp. 3, but were not inseminated. Progesterone concentrations were assessed in plasma collected during the estrous cycle following synchronization. Ultrasonography was used to monitor ovarian dynamics and to diagnose pregnancy. In Exp. 1, the mean number of ovulations was affected (P < 0.02) by the dose of eCG and the stage of follicular development when administered. Treatment with eCG on d 2 tended (P < 0.08) to extend the interval from PGF2α to ovulation, but was not successful in inducing double ovulations. In contrast, eCG on d 3 increased (P < 0.01) the number of cows with double ovulation when administered i.m. and increased (P < 0.04) pregnancy rate in single ovulating heifers after bull breeding (68.0 vs. 53.1%). This treatment also elevated progesterone concentrations during the estrous cycle following synchronization. Thus, the mechanism by which administration of eCG on d 3 of the synchronization increased pregnancy rates may be through supporting development of a healthy follicle and subsequent corpus luteum capable of secreting increased concentrations of progesterone during early pregnancy. In conclusion, strategic administration of eCG during a synchronization protocol can be used to improve reproductive performance through increased pregnancy rates in single ovulating animals as well as the induction of twin ovulations for twinning.

Intravaginal progesterone devices in synchronization protocols for artificial insemination in beef heifers

Two experiments were designed to investigate the administration of intravaginal progesterone in protocols for oestrus and ovulation synchronization in beef heifers. In Experiment 1, cyclic Black Angus heifers (n = 20) received an Ovsynch protocol and were randomly assigned to receive (CIDR-Ovsynch) or not (Ovsynch) a progesterone device between Days 0 and 7. Treatment with a controlled internal drug release (CIDR) device significantly increased the size of the dominant follicle prior to ovulation (12.8 ± 0.4 CIDR-Ovsynch vs 11.4 ± 0.4 Ovsynch) (p < 0.02). Plasma progesterone concentrations throughout the experiment were affected by the interaction between group and day effects (p < 0.004). In Experiment 2, cyclic Polled Hereford heifers (n = 382) were randomly assigned to one of the six treatment groups (3 × 2 factorial design) to receive a CIDR, a used bovine intravaginal device (DIB), or a medroxiprogesterone acetate (MAP) sponge and GnRH analogues (lecirelin or buserelin). All heifers received oestradiol benzoate plus one of the devices on Day 0 and PGF on Day 7 pm (device withdrawal). Heifers were detected in oestrus 36 h after PGF and inseminated 8-12 h later, while the remainder received GnRH 48 h after PGF and were inseminated on Day 10 (60 h). The number of heifers detected in oestrus on Day 8 and conception rate to AI on Day 9 were higher (p < 0.01) in the used-DIB than in the CIDR or MAP groups, while the opposite occurred with the pregnancy rate to FTAI on Day 10 (p < 0.01). There was no effect of progesterone source, GnRH analogue or their interaction on overall pregnancy rates (64.9%). Progesterone treatment of heifers during an Ovsynch protocol resulted in a larger pre-ovulatory follicle in beef heifers. Progesterone content of intravaginal devices in synchronization protocols is important for the timing of AI, as the use of low-progesterone devices can shorten the interval to oestrus.

Where there's smoke...carbon monoxide exposures in smoking and smoke-free workplaces

Comparisons of expired air carbon monoxide levels in non-smoking staff in six licensed clubs (a smoking workplace) were made with those of non-smoking staff of a large public hospital (a smoke-free workplace). There was a significant difference between clubs and hospital in levels of CO at end of work. The average concentration of club workers was 8.7 ppm (Hospital, 5.3 ppm). Approximately one third of these non-smokers in licensed clubs exceeded 10 ppm putting them in the 'light smoker' category according to the manufacturer of the monitoring equipment. Club workers increased their CO level during work time by four times the increase of Hospital staff. This study suggests that there are significant gains to be made in reduction of intake of harmful passive-smoking products by removing tobacco smoke from workplaces.

27 FOLLICULAR RESPONSE TO DIFFERENT eCG DOSES IN AN OVSYNCH + PROGESTERONE PROTOCOL IN BEEF HEIFERS

An experiment was designed to evaluate the effect of different doses of eCG on ovarian follicular dynamics in heifers treated with a Ovsynch plus progesterone protocol. Twenty-five cyclic yearling Black Angus heifers (373.0 ± 35.7 kg), in 2 replicates, received an injection of 100 μg of GnRH (Ovurelin, Bomac Laboratories Ltd., Auckland, New Zealand) i.m. and an intravaginal progesterone device (1.38 g of progesterone; Eazi-Breed CIDR, Pfizer Animal Health, New Zealand) on Day 0 (beginning of the experiment), followed by 500 μg of cloprostenol (PGF, Estrumate, Intervet/Schering-Plough Animal Health, Auckland, New Zealand) i.m. on Day 7, and a second 100 μg of GnRH injection given i.m. on Day 9 (56 h after PGF). At the time of PGF treatment, heifers were randomly assigned to 5 treatment groups to receive 0, 300, 500, 700, or 1000 IU of eCG (Folligon, Intervet/Schering-Plough Animal Health) i.m. Heifers were monitored by ultrasonography (Aloka 900-SSD equipped with a 7.5-MHz linear-array transducer; Aloka, Tokyo, Japan) daily from Day 0 to 9 (GnRH), and then every 12 h until ovulation. Data were analyzed by one-way ANOVA or Kruskall-Wallis test, and means or ranks were compared with LSD or Wilcoxon rank sum tests, respectively. Because a replicate effect was observed (P < 0.05) in the size of the dominant follicle at the second GnRH and prior to ovulation, replicate effect was included in the analysis. The luteal area at PGF treatment was significantly greater (P < 0.01) in heifers that ovulated (750.0 ± 97 mm2) in response to the first GnRH treatment than in those that did not (301.6 ± 42.7 mm2). The diameter of the dominant follicle at the time of PGF treatment was also greater (P < 0.05) in ovulating (11.2 ± 0.4 mm) than in nonovulating (9.7 ± 0.5 mm) heifers. The interval from the first GnRH treatment to the emergence of the next follicular wave was longer (P = 0.50) and more variable in heifers that did not ovulate (2.9 ± 0.4 d; n = 27) than in those that ovulated (1.9 ± 0.2 d; n = 23). There was no effect (P < 0.37) of eCG on the interval from PGF to ovulation (86 ± 1.9 h). The number of ovulations after the second GnRH was higher (P = 0.01) in the group of heifers treated with 1000 IU of eCG (1.8 ± 0.4) than in the other groups (1.0 ± 0.0; 1.1 ± 0.1; 1.2 ± 0.1; 1.0 ± 0.1). There was an effect of day of follicular wave emergence on the number of ovulations (P < 0.01). Heifers with a wave emerging 1 to 3 days after the first GnRH (n = 37), had one ovulation (1.0 ± 0.0), whereas heifers with a wave emerging on Day 4 (3 out of 4 heifers) and Days 5 to 7 (n = 9), ovulated 2 or more follicles. In summary, the multiple ovulation effect occurred when eCG was given to heifers with a follicular wave emerging on or after Day 4, and was potentiated when heifers received 1000 IU of eCG. Although the dose of eCG given at the time of PGF treatment in an Ovsynch program has a significant effect on follicular development, the time of emergence of the dominant follicle appeared to be more important in the ovulation of preovulatory follicle/s after the eCG and the second GnRH treatment.

36 FOLLICULAR DYNAMICS IN PROLIFIC SHEEP: PGF-BASED ESTRUS SYNCHRONIZATION

A study was designed to compare the effect of a prostaglandin-based synchronization protocol on ovarian follicular dynamics in sheep with the FecB (Booroola) mutation. Forty dry Romney sheep (57.6 ± 7.3 kg; 6.1 ± 1.1 years) were randomly selected from both Invermay Booroola (BB; n = 20) and commercial (non-FecB carriers, ++; n = 20) flocks. All ewes had their estrous cycles synchronized with 2 i.m. injections of PGF (150 μg of cloprostenol, Estrumate, Schering-Plough Coopers Animal Health Ltd., New Zealand) administered 7 days apart. Ewes were monitored by transrectal ultrasonography (Aloka 900-SSD and a 7.5-MHz linear-array transducer, Aloka, Tokyo, Japan) daily from Day -2 to the day of ovulation. Data were analyzed by Student’s t-test or Wilcoxon Rank Sum test. Variances were compared with Barlett’s test. Paired t-test compared the number of preovulatory follicles in each genotype after PGF treatments and intervals from PGF to ovulation after PGF. Data are presented as mean (± SEM). The number of corpora lutea (CL) and total CL area at the time of the first and second PGF treatment were 4.4 ± 0.6; 5.7 ± 1.4 and 672.1 ± 133.5 mm2; 999.0 ± 145.9 mm2 in the BB and 2.1 ± 0.2; 2.1 ± 0.5 and 342.3 ± 60.7 mm2; 401.3 ± 68.6 mm2 in ++ ewes, respectively. These 2 variables were higher (P < 0.01) at both PGF injections in the BB than in the ++ ewes, except the CL area at the time of first PGF treatment (P = 0.15). The largest follicle diameter at the time of the first and second PGF treatments was smaller (P < 0.003) in BB (4.1 ± 0.3 mm; 3.5 ± 0.2 mm) than in ++ (5.3 ± 0.3 mm; 5.8 ± 0.1 mm) ewes. The median and mean number of follicles that ovulated after the first and second PGF treatment were higher (P < 0.0001) in BB (6 & 7; 5.7 ± 0.3; 6.9 ± 0.3; difference = 1.2 ± 0.4; P < 0.003) than in the ++ (2 & 2; 2.1 ± 0.1; 2.1 ± 0.1) sheep. The luteal area at the time of first and second PGF in both BB and ++ did not differ (P = 0.3). The intervals from the first and second PGF to the respective ovulations did not differ (P > 0.61) between BB (3.4 ± 0.2; 3.0 ± 0.3d) and ++ (3.5 ± 0.2d; 3.0 ± 0.1d) ewes. However, interval from the second PGF to ovulation was more variable (P = 0.002) in the BB than in the ++ ewes. Data of both groups were combined and a mean significant difference of 0.6 ± 0.2d (P < 0.003) was found between the first and second PGF-to-ovulation intervals. The interval from the first PGF to emergence of the next follicular wave was shorter (P < 0.02) and more variable (P < 0.03) in the BB (2.7 ± 0.4d) than in the ++ (3.5 ± 0.2 d) group. Preovulatory follicles were smaller in Booroola, but higher in number, than in ++ ewes, whereas the luteal area was similar. Within the BB ewes, the higher number of follicles that ovulated after the second PGF than after the first injection may be due to a higher follicular response to an elevated rebound in circulating FSH after the first PGF. A high number of growing follicles of the first follicular wave may also have contributed to this event. These findings warrant further research aimed at the study of the interaction between FSH and follicle dynamics in estrus synchronized sheep carrying the FecB mutation.

219. Prevalence of sperm chromatin instability amongst bulls in a subtropical environment: a preliminary investigation

During mammalian spermiogenesis nucleosomal histone proteins bound to DNA are replaced by protamines. The integrity and stability of the protamine-DNA association in sperm can be measured using the sperm chromatin structure assay (SCSA). The recent emergence of compelling information from assisted reproduction in humans of a relationship between sperm chromatin stability and the establishment and maintenance of pregnancy has led to considerable interest in production and recreational animals.1 The aim in the present study was to determine the incidence of sperm chromatin instability amongst bulls in a subtropical region of northern Australia, as a first step in evaluating whether sperm chromatin instability is a contributing factor to reproductive wastage in cattle. Semen was obtained from 565 Bos indicus and Bos indicus x taurus bulls from northern and central Queensland aged between 20months and 10years. Samples were subjected to standard semen evaluation2 and aliquots stored in liquid nitrogen until chromatin integrity was determined using the SCSA.3 Samples exposed to the SCSA for 0.5min revealed 4.9% of bulls had a DFI >27% and this increased to 11.5% of bulls with DFI >27% when samples were exposed to the SCSA for 5 min. DFI was significantly correlated with sperm density, mass activity, motility and morphology. Location appeared to have a greater influence on DFI than genotype. Preliminary data from a small sample of bulls would suggest that a relatively high DFI can be repeatable for individual bulls. These findings indicate that sperm chromatin instability occurs in bulls in northern Australia although the prevalence might be considered to be relatively low. The relationship of sperm chromatin instability to the contribution of bulls to embryonic mortality requires further study and likewise the impact on reproductive wastage remains to be determined. (1)Boe-Hansen GB et al. (2005). Theriogenology 63, 1789.(2)Fitzpatrick LA et al. (2002). Anim. Reprod. Sci. 71, 39.(3)Evenson D and Jost L (2000). Methods Cell Sci. 22, 169.