Effects of different doses of estradiol benzoate used in a cervical relaxation protocol on the success of non-surgical embryo recovery and luteal function in superovulated ewes

This study investigated the effectiveness of different doses of estradiol benzoate (EB) to promote cervical relaxation and their effects on luteal function and outcomes of non-surgical embryo recovery (NSER) in sheep. Multiparous (MULT) and nulliparous (NULL) crossbred Lacaune X Santa Inês ewes were superovulated and naturally bred. Seven days after progesterone withdrawal, females were randomly assigned to one of three distinct cervical relaxation protocols, consisting of i.m. treatment with 37.5 µg d-cloprostenol and different doses of EB: 0.0 mg (0.0EB group; n = 3 NULL and 14 MULT); 0.5 mg (0.5EB group; n = 4 NULL and 12 MULT) or 1.0 mg (1.0EB group, n = 6 NULL and 11 MULT) 16 h before NSER. All ewes received 50 IU of oxytocin 20 min before NSER (D17). Blood samples were collected and ultrasound exams (B-mode and color Doppler) were performed at two timepoints: immediately before d-cloprostenol and EB treatments and prior to NSER. Estrous behavior, corpora lutea count and NSER success outcomes were not affected by EB treatments nor parity (P > 0.05). Embryo recovery rate was greater for ewes in the 0.5EB group and in the NULL ewes (P < 0.05). Ovarian biometrics differed between the two evaluation timepoints in all groups (P < 0.05). Plasma estradiol increased over time, reaching a significant greater level in 1.0EB ewes compared to controls on D17 (P < 0.05), whereas progesterone concentrations decreased over time in all groups (P > 0.05). In conclusion, treatments did not affect NSER success but they did affect luteal function by altering P4 and E2 concentrations. Therefore, the NSER technique can be successfully performed in ewes with or without prior treatment with EB.

121 Anti-Müllerian hormone cutoff values for the selection of oocyte donors in the Gir (Bos indicus) breed

Anti-Müllerian hormone (AMH) has a well-known association with antral follicle count (AFC) and the number of oocytes recovered by OPU in cattle. However, to be used as a criterion to select candidate donors for ART, AMH reference values must be established for each breed. The aim of this study was to estimate AMH cutoff values for selecting oocyte donors in Gir (Bos indicus) cattle. A blood sample was collected at a random day of oestrous cycle from Gir heifers (n=120) at 23.3±0.5 months of age, and the plasma was stored for further AMH analysis by ELISA, using a commercial kit (AL114, AnshLabs) in a private laboratory (LEAC, Sao Paulo, Brazil). Data from 506 ovum pickup-invitro embryo production (OPU-IVEP) sessions (4.2±0.2 per donor) performed in these heifers from 2017 to 2019, starting 120 days after blood sampling, were then analysed. Donors were ranked in quartiles according to the number of total oocytes recovered, viable oocytes recovered, and embryos produced. Those classified in the first quartile for each endpoint were considered poor responders. The AMH values were then analysed using the receiver operating characteristic (ROC) curve, and cutoff values for each endpoint were estimated based on best values for sensitivity and specificity. A second analysis was performed to check which cutoff value would result in a significant increase in average for each endpoint. The OPU-IVEP data were ranked according to corresponding AMH values (smaller to greater), and the average of the selected group of donors was compared with the original group by ANOVA, using the PROC GLM of SAS (SAS Institute Inc.), after successive exclusion of donors with lower AMH concentrations. Results are shown as mean±s.e.m. On average, heifers presented AMH concentrations of 932.9±48.4pgmL−1 (ranging from 112.7 to 2044.8pgmL−1) and produced 32.3±1.5 total oocytes, 25.9±1.4 viable oocytes, and 5.3±0.4 embryos per OPU-IVEP session. The heifers ranked in the third and last quartiles yielded more total oocytes, viable oocytes, and blastocysts than those ranked in the first quartile (P&lt;0.05). Based on the total number of oocytes recovered (59.2±3.1), heifers of the last quartile had an estimated AFC &gt;60. The area under the ROC curve (AUC) for total oocytes, viable oocytes, and embryos produced were 0.77 (P&lt;0.0001), 0.75 (P&lt;0.0001), and 0.72 (P=0.0003), and the estimated cutoffs for AMH concentration were 761.4, 622.5, and 681.5pgmL−1, respectively. After successive exclusions of donors with lower AMH values, averages were greater (P&lt;0.05) at a cutoff value of 632.4pgmL−1 for total oocytes (36.9±1.6 vs. 32.3±1.5; +15.3%), 672.3pgmL−1 for viable oocytes (30.3±1.4 vs. 25.9±1.4; +19.4%), and 776.8pgmL−1 for embryos produced (6.6±0.3 vs. 5.3±0.4; +23.4%). However, the use of these cutoff values to increase the averages would result in the exclusion of 32.8, 37.9, and 50.0% of the potential donors for each endpoint, respectively. In summary, these results demonstrated that an AMH concentration of approximately 700pgmL−1 can be used to select donors with higher oocyte yield and thus to increase IVEP outcomes in Gir heifers. This research was supported by Fazendas do Basa, Fapemig CVZ APQ 03430-17.

Short communication: Does previous superovulation affect fertility in dairy heifers?

The aim of this study was to evaluate the potential negative effects of superovulation on subsequent fertility of dairy heifers. Holstein heifers (n = 1,783), 312 to 387 d of age, and 273 to 307 kg of body weight (BW) from 2 commercial farms were enrolled. These animals were first selected to be donors (446) or nondonors (CON, n = 1,327) according to their genomic values. Nondonor heifers (CON) were artificially inseminated (AI) according to standard procedures of each farm after reaching 320 kg of BW. Donor heifers were superovulated using a fixed FSH dose (180 mg NIH-FSH-P1; Folltropin-V, Vetoquinol Brasil, Mairiporã, SP, Brazil) and embryos were collected following standard procedures. Heifers that produced fewer than 8 viable embryos after first superovulation (SOV1, n = 337) were no longer used as donors, whereas the remaining heifers (SOV2, n = 109) were superovulated a second time within an interval of 48 to 54 d. Donor heifers (SOV1 and SOV2) were AI once they reached 320 kg of BW, at least 15 d after the last embryo collection. Data on age at first AI, at conception, and at parturition, as well as the number of services per conception, were analyzed by ANOVA, using the PROC MIXED procedure of SAS (SAS Institute Inc., Cary, NC) procedure. Binomial variables (pregnancy per AI, overall pregnancy rate, open heifers at 500 d age, and late pregnancy loss) were analyzed using the GLIMMIX procedure of SAS. The heifers selected to undergo superovulation twice (SOV2) yielded more total (12.6 ± 5.3 vs. 6.8 ± 4.6; respectively) and viable embryos (8.5 ± 3.8 vs. 3.9 ± 2.8; respectively) than those superovulated only once (SOV1). Age at first AI, conception, and at parturition was greater in SOV2, but not in SOV1 compared with nondonor controls. In addition, pregnancy per first AI, overall pregnancy rate, services per conception, open heifers at 500 d of age, and occurrence of pregnancy losses after 60 d of gestation were similar among CON, SOV1, and SOV2 heifers. In summary, a single superovulation performed before heifers reach a minimum weight for breeding did not affect age at conception, calving or other indicators of reproductive efficiency. On the other hand, heifers superovulated twice were first inseminated at a later age than their birth cohorts, but had similar reproductive performance.

83 Pregnancy losses after transfer of bovine embryos produced by assisted reproductive technologies

The aim of this study was to evaluate risk factors for pregnancy loss in embryo recipients. We evaluated data from 31,792 embryo transfers (ET), including 859 embryos derived in vivo (IVD), 28,814 produced in vitro (IVP), and 2,119 produced by somatic cell nuclear transfer (SCNT), recorded from 2008 to 2012 on a single commercial farm. Embryos were produced by different in vitro embryo production laboratories, but ET was performed by the same team and within the same herd. Recipients were checked for pregnancy (PR) by ultrasonography 23 days after ET and re-examined on Days 60, 90, and 120 of gestation to identify pregnancy losses (PL). Data were analysed for the main effect of embryo production technique upon PL. For IVD and IVP embryos only, additional risk factors were included in the statistical model, including cryopreservation, type of semen (conventional, sex-sorted, reverse sex-sorted), embryo developmental stage, recipient corpus luteum quality score, use of natural oestrus or synchronization protocol, embryo-recipient synchrony, embryo genetics (taurine v. zebu, dairy v. beef), season (summer v. winter), and fetal sex. Data were analysed using the GLIMMIX procedure of the SAS Software (v 9.3, SAS Institute Inc., Cary, NC, USA). Overall PR was 42.1% (13,395 of 31,792) and PL between days 30 and 60, 60 and 90, and &gt;90 were 8.7, 5.3, and 3.5%, respectively (cumulative PL=17.4%). The SCNT embryos had lower PR compared to IVP and IVD embryos (36.6, 42.5, and 44.2%, respectively; P&lt;0.001) as well as a greater PL in all periods (30-60=45.2, 6.4, and 8.2%; 60-90=3.5, 1.4, and 1.8%; and &gt;90=21.4, 6.3, and 7.1%, respectively; P&lt;0.0001). The PR was similar between fresh and frozen embryos, but lower for vitrified ones (42.9, 43.1, and 39.1%, respectively, P&lt;0.05). Slow freezing resulted in a greater total PL compared to fresh embryos (18.0v. 13.9%, respectively; P&lt;0.05). We observed an interaction between embryo genetics and season. The taurine dairy subgroup had the lowest PR during summer (37.7v. &gt;41.7% in all other groups; P&lt;0.01), but within this group PR increased during winter (37.7v. 44.6%, P&lt;0.05). The PL was greater for taurine than zebu during summer (17.8v. 14.0%; P&lt;0.001), but did not differ during winter (P&gt;0.05). The type of semen, embryo developmental stage, corpus luteum quality score, and embryo recipient synchrony affected pregnancy rates (P&lt;0.05) but not pregnancy losses (P&gt;0.05). Interestingly, the use of ovulation synchronization protocols resulted in similar pregnancy rates but greater pregnancy losses compared to natural oestrus (41.8v. 43.2%, P&gt;0.05; and 15.9v. 22.1%, P&lt;0.05, respectively). Pregnancy loss after 60 days was similar between female and male fetuses (5.0v. 4.9%, respectively; P&gt;0.05). In summary, the assisted technology used to produce and freeze embryos was the main cause of variation in pregnancy losses, which were also affected by the interplay of season by genetic background and by the use of synchronization protocols. Conversely, factors known to affect pregnancy rates, such as embryo developmental stage, corpus luteum quality, and embryo-recipient synchrony, had no effect upon pregnancy loss. Research was supported by Mineirembryo, CAPES, and FAPDF.

Differential expression of LHCGR and its isoforms is associated to the variability in superovulation responses of Gir cattle

The aim of this study was to evaluate the pattern of expression of LHCGR isoforms in Gir heifers characterized as good (10.3 ± 1.2 ova/embryos per flush, n = 5) or poor responders (1.1 ± 0.3 ova/embryos per flush, n = 5) to superovulation protocols. In both groups, an adapted ultrasound-guided follicular aspiration system was used to collect granulosa cells from 8 mm follicles formed either during a synchronized, non-stimulated follicular wave (no stimulation control, NS) or on the fourth day of a superovulation protocol (SOV) induced with 200 IU of pFSH. The recovered follicular fluid was centrifuged and granulosa cells were washed with NaCl 0.9% and kept in RNAlater^®. RNA extraction was performed using a commercial RNeasy Micro Kit and eluted samples were quantified and reverse transcribed using the commercial Superscript III kit. cDNA samples were amplified by real-time PCR using a primer to target LH/hCG receptor gene - not selective for LHCGR isoforms (total LHCGR) - and four sets of isoforms selective primers (S1, S10, S10 + 11, and S11). Analyses were performed using the REST software and expression levels are shown as mean ± SEM. Under physiological conditions (NS), poor responders had a higher expression of total LHCGR (4.9 ± 1.7 fold-change, P < 0.01) as well as isoforms S10, S11 and S10 + 11, compared to good responders. In both phenotypes, superovulation down-regulated total LHCGR expression (-0.5 ± 0.2 and -0.9 ± 0.0 for good and poor responders, respectively; P < 0.05). However, in poor responders the exogenous FSH treatment up-regulated the S10 (2.4 ± 2.0; P < 0.05), S10 + 11 (3.8 ± 3.2; P < 0.01), and S1 isoforms (1.8 ± 1.3; P < 0.05), compared to good responders We conclude that down-regulation of total LHCGR, associated to up-regulation of their inactive isoforms, may have compromised follicle development and thus contributed to the low efficiency of superovulation in heifers with a poor responder phenotype.

101 Effects of Active Immunization Against GnRH in Oocyte Donors with Cystic Ovarian Disease

Cows intensively used as oocyte donors for in vitro embryo production (IVEP) are usually kept nonpregnant for prolonged intervals, exposed to successive hormonal treatments, and frequently become overweight. These are all risk factors for the development of endocrine unbalance and, consequently, cystic ovarian disease (COD). The aim of this study was to evaluate the effect of active immunization against gonadotropin-releasing hormone (GnRH) on (1) ovarian follicular population, and (2) development potential of oocytes used for IVEP. Nelore (Bos indicus) cows (n = 14), previously diagnosed with chronic COD (Faria et al. 2017 Anim. Reprod., in press), weighing 620.0 ± 12.8 kg and with body condition score of 4.1 ± 0.2, were assigned to control (n = 6) or treatment (n = 8) group. Cows in the treatment group received 2 SC injections of 1.0 mL of anti-GnRH vaccine (Bopriva, Zoetis, Brazil), 28 days apart (weeks 0 and 4), whereas cows in the control group received placebo on the same schedule. Transrectal ultrasonography was performed weekly from week 0 to evaluate the number and distribution of follicles among size classes, endometrial thickness, and clinical presence of mucometra. Immunization was considered effective (E-IM) when no follicles ≥5.0 mm were observed on the ovaries during a given examination. Cows having E-IM were then used as oocyte donors for IVEP. Cumulus-oocyte complexes (COC) were collected in 5 consecutive ovum pick-up weekly sessions. As a control for IVEP, oocytes from a slaughterhouse were used, with similar procedures performed on the same days and using the same semen batch. The MIXED procedure of SAS (SAS Institute Inc., Cary, NC, USA) with repeated-measures statement was used to evaluate the effects of treatment, time, and interactions on ovarian endpoints; and the GLM procedure was used to analyse embryo production data. Results are shown as mean ± SEM. There were time and time × treatment effects on ovarian parameters. Treated cows had a decrease (P < 0.05) in the average diameter of the largest follicle and in the number of follicles ≥8 mm, and an increase (P < 0.05) in follicular population after week 6. Nonetheless, individual response to treatment was variable: only 50% of the cows (4 of 8) were E-IM at week 8, whereas 25% (2 of 8) still had COD (largest follicle ≥18.0 mm) at this timepoint. Overall, a negative correlation was detected between follicular population and the diameter of the largest follicle (r = –0.60, P < 0.0001) or the number of follicles ≥8 mm (r = –0.47, P < 0.0001). There was no effect (P > 0.05) of treatment on endometrial thickness or mucometra score. Cows with E-IM produced 22.2 ± 3.6 total and 12.9 ± 2.3 viable COC. Cleavage rate did not differ between E-IM and control (slaughterhouse) oocytes (70.8 ± 7.0 v. 75.1 ± 3.0%, respectively; P > 0.05); however, blastocyst rate was greater in the E-IM group compared with controls (39.7 ± 5.5 v. 20.5 ± 4.7%, respectively; P < 0.02). In summary, our results suggest that active immunization against GnRH leads to variable results in the distribution of the follicular population in cows with COD, but it does not negatively affect IVEP efficiency. This research was supported by Zoetis, CNPq, and CAPES.

134 Effects of Gas Tension During Culture upon Development of Bovine Embryos from Beef (Nellore) and Dairy (Girolando) Breeds

Culture of bovine embryos is a critical step during in vitro embryo production (IVEP) and, as such, has been the focus of numerous studies on cattle IVEP. Improvements of culture conditions to mimic the in vivo maternal microenvironment involves studying the optimal gas tension for pre-implantation embryonic development. In the commercial conditions, there is great variability in results, in part because of the difference between breeds and donors. The objective of this study was to evaluate the effects of culture in high or low oxygen tension upon the development of embryos from a crossbred dairy breed (Girolando F1; Gir × Holstein) and a beef Bos indicus breed, Nellore. We collected data from an IVEP commercial operation located in a tropical area of southeastern Brazil (Minas Gerais State) from February to May 2017. The study was designed in a 2 × 2 factorial arrangement of treatments: 2 O2 tensions during culture (5%, low O2 v. 20%, high O2) and 2 breeds (Nellore, beef v. Girolando F1, dairy). Thus, the following 4 groups were studied: Nellore-high O2 (n = 86 donors), Nellore-low O2 (n = 107 donors), Girolando F1-high O2 (n = 114 donors), and Girolando F1-low O2 (n = 110 donors). Outcome variables were the number of cleaved embryos 72 h post-insemination (hpi), cleavage rate relative to the total number cumulus–oocyte complexes (COC) put in culture, number and percentage of blastocysts 192 hpi relative to the structures kept in culture. Variables that were not normally distributed were transformed using the formula log(y + 0.05). Data were analysed using the GLM procedure of SAS (SAS Institute Inc., Cary, NC, USA) for the main effects of gas tension (low v. high O2) and breed (Girolando F1 v. Nelore). Results are shown as mean ± SEM. Gas tension affected the number of cleaved embryos (10.52 ± 0.92 v. 8.33 ± 0.72 for high and low O2, respectively; P < 0.01) and cleavage rates (40.58 ± 2.49 v. 44.41 ± 2.88 for high and low O2; P < 0.01 in Nellore), but did not affect these variables in Girolando F1 donors (13.23 ± 1.33 v. 10.76 ± 0.76 cleaved embryos, for high and low O2; P = 0.63; 58.01 ± 2.00 v. 60.19 ± 1.97 cleavage rate, for high and low O2; P = 0.80). Nonetheless, the number and percentage of blastocysts were not affected by gas tension in either breed. Results for Nellore were 4.99 ± 0.56 v. 3.51 ± 0.38 blastocysts in high and low O2, respectively (P = 0.051) and 41.92 ± 3.91% v. 39.81 ± 3.77% blastocysts, in high and low O2 (P = 0.11). For Girolando F1, numbers of blastocysts were 5.84 ± 0.66 v. 4.24 ± 0.39 in high and low O2 (P = 0.19) and percentage of blastocysts 49.14 ± 2.97% v. 49.11 ± 3.40% in high and low O2 (P = 0.46). These results suggest that oxygen tension during culture affects IVEP differently depending on breed. The initial period of culture, recognised as critical in IVEP, seemed more sensitive to high O2 tension, particularly in Nellore.

Intrafollicular oestradiol production, expression of the LH receptor (LHR) gene and its isoforms, and early follicular deviation in Bos indicus

The aim of the present study was to characterise the roles of intrafollicular oestradiol production and granulosa cell (GC) expression of the LH receptor (LHR) gene and its isoforms during follicular deviation in Bos indicus. Follicular wave emergence was synchronised in heifers from a Bos taurus dairy (Holstein; n = 10) and a B. indicus dairy breed (Gir; n = 10). Follicles were aspirated individually at sizes corresponding to the periods of predeviation, deviation and postdeviation. Intrafollicular oestradiol (IF-E2) and progesterone (IF-P4) concentrations were determined in the follicular fluid (FF) by radioimmunoassay, and relative expression of P450 aromatase (CYP19A1) and LHR forms was evaluated in GC using real-time quantitative–polymerase chain reaction. Despite differences in the size of the dominant follicle at deviation, changes in CYP19A1 expression and IF-E2 concentrations were similar in follicles of the same diameter in both breeds. A peak in total LHR expression occurred after follicular deviation in association with low expression of LHR isoforms. The results suggest that regulation of LHR function by sequential changes in the expression pattern of LHR isoforms may play a role in the early deviation of the dominant follicle, as observed in B. indicus breeds.

175 CONSEQUENCES OF IN VITRO PRODUCTION OF EMBRYOS WITH OR WITHOUT COLONY-STIMULATING FACTOR 2 IN CULTURE MEDIUM ON MORPHOMETRIC FEATURES OF THE BOVINE CONCEPTUS AT DAY 86 OF GESTATION

In vitro production (IVP) of embryos can disrupt fetal and placental development and increase risk of abnormal fetal growth. Maternal factors play a role in developmental programming of the early embryo. Colony-stimulating factor 2 (CSF2) is present in the oviduct and endometrium and has improved competence of the pre-implantation embryo to establish pregnancy in cattle. The objective was to determine whether CSF2 during embryo culture alters fetal development and alleviates abnormalities associated with IVP. Holstein oocytes were matured and fertilised in vitro with X-sorted semen from a Holstein bull. Putative zygotes were cultured in SOF-BE1 at 5% CO2 and 5% O2 for 5 days and then randomly assigned to receive vehicle (IVP-control) or 10 ng mL–1 CSF2 (IVP-CSF2). Grade I blastocysts were transferred on Day 7 to Holstein recipients that were previously randomised to receive an IVP-control or an IVP-CSF2 embryo. A third group of cows included in the randomization was assigned to be artificially inseminated on Day 0 using the same bull as for IVP (AI). Pregnancy was terminated on Day 85 or 86. Statistical analysis was performed by analysis of variance using the GLM procedure of SAS with contrasts for AI v. (IVP-control+IVP-CSF2) (contrast 1; C1) and IVP-control v. IVP-CSF2 (contrast 2; C2). Results are least squares means ± s.e.M. A total of 23 morphometric measurements of placenta and fetus were made on 9 AI, 12 IVP and 7 CSF2 female singletons. Conceptuses derived by IVP (IVP-control and IVP-CSF2) differed from those derived by AI for 4 characteristics including fetal bodyweight (142.9 ± 4.7, 157.2 ± 4.4, and 162.6 ± 6.1 g for AI, IVP-control and IVP-CSF2, respectively; C1, P = 0.0237), eviscerated weight (102.9 ± 3.4, 113.6 ± 3.2, and 112.2 ± 4.4 g; C1, P = 0.0602), crown-rump length (CRL) (13.7 ± 0.2, 14.0 ± 0.2, and 14.7 ± 0.3 g; C1, P = 0.0434; C2, P = 0.0631) and umbilical cord diameter (0.85 ± 0.08, 1.1 ± 0.08, and 0.91 ± 0.1 cm; P = 0.0519). Note that while IVP-CSF2 conceptuses were generally similar to those for IVP-control, CRL tended to be highest for IVP-CSF2. Also, umbilical cord diameter for IVP-CSF2 was similar to AI and lower than IVP-control. Data from 1 fetus in the IVP-CSF2 group was excluded from analysis because it had a phenotype consistent with large offspring syndrome. Bodyweight (354 g) was 2-fold larger than other fetuses (average = 155 g) and placental weight was 7-fold greater (1505 v. 211 g). In addition, organs were enlarged and severe ascites and hemorrhagic cotyledons were observed. In conclusion, IVP resulted in increased fetal size and umbilical cord diameter without other significant effects on placental morphometry. CSF2 did not alleviate adverse effects of culture on fetal growth, exacerbating effects on CRL, but did reduce effects of IVP on umbilical cord diameter. Gene expression analysis may be useful for further characterisation of effects and elucidation of mechanisms involved. This project was supported by USDA NIFA Grant 2011–67015–30688.

9 TIMED ARTIFICIAL INSEMINATION IN BLOCKS: A NEW ALTERNATIVE TO IMPROVE FERTILITY IN BEEF COWS

The objective of this study was to evaluate whether timed artificial insemination (TAI) according to the diameter of the dominant preovulatory follicle (POF) would improve pregnancy rates in beef cows. In Experiment 1, a retrospective meta-analysis of 5 oestradiol- or gonadotropin-releasing hormone-based TAI experiments from 2011 to 2014 was performed to evaluate the interval from luteolysis to ovulation. In these experiments, crossbred cows (Gyr × Holstein; n = 60) were examined by ultrasonography at 12-h intervals from progesterone-releasing device (CIDR) removal to ovulation. A linear regression model was used to predict the effect of POF diameter on the time of ovulation. Cows with a larger POF at the time of AI ovulated earlier than cows with smaller POF (y = –8.25x + 115.22; R2 = 0.93; P < 0.0001). In Experiment 2, lactating Nelore cows (Bos indicus; n = 59) on random days of the oestrous cycle were given 2 mg of oestradiol benzoate IM and a CIDR device (Day 0) to synchronize follicular waves. The CIDR were removed, and cows were given 500 μg of d-Cloprostenol (prostaglandin F2α) IM, 1 mg of oestradiol cypionate IM, and 300 IU of eCG IM on Day 8. On the morning of Day 10 (07:00 a.m.), the diameter of the POF was assessed by ultrasonography, and cows were randomised into Control (n = 29) and Block (n = 30) groups. 1) Control-group cows were TAI 48 h after CIDR removal (08:00 a.m. on Day 10), and Block-group cows were inseminated at 4 time points according to the diameter of the POF: B0 (POF ≥15 mm, TAI at 08:00 a.m. on Day 10, n = 6), B1 (POF 13 to 14 mm, TAI at 02:00 p.m. on Day 10, n = 8), B2 (POF 11 to 12 mm, TAI at 08:00 a.m. on Day 11, n = 11), and B3 (POF ≤ 10 mm, TAI at 02:00 p.m. on Day 11, n = 5). Pregnancy status was assessed 30 days post-AI by ultrasonography. No differences were detected in the diameter of the POF 48 h after CIDR removal (P = 0.77) or ovulation rate (P = 0.65; combined ovulation rate 52/59, 88%) between Control and Block groups. Block group had a higher pregnancy rate than Control (22/30, 73% v. 13/29, 45%, respectively; P = 0.02). In conclusion, our results document that interval from luteolysis to ovulation depends on the size of preovulatory follicle, timing of AI in relation to ovulation time is critical, and AI time according to the diameter of the POF can be an effective tool to improve fertility of cows in TAI protocols.

117 INDUCTION OF OVULATION WITH ESTRADIOL BENZOATE AFFECTS THE PROGRESSION OF VASCULARIZATION IN PREOVULATORY FOLLICLES

Ovarian changes in blood supply have been related to follicle growth and ovulation in cattle. The aim of the present study was to characterise the vascularization pattern of the preovulatory follicle in cows induced to ovulate with a timed AI (TAI) protocol using oestradiol benzoate. Follicular wave was synchronized in 18 crossbred cows (Holstein × Gir) with the following protocol: Day 0 (D0), insertion of an intravaginal device of progesterone (1 g, P4) and IM injection of oestradiol benzoate (2 mg, EB); D9, intravaginal P4 device was removed and all the animals received IM injections of cloprostenol (0.53 mg) and eCG (300 IU); D10, animals were randomly allocate into 2 groups, which received 1 mL of saline (control group) or 1 mg of EB (EB group). The vascularization of the largest follicle present in the ovaries was evaluated by colour Doppler ultrasonography immediately before treatment (0 h–0 h) and every 6 h thereafter, up to 84 h or until ovulation was detected. The colour Doppler signals present in the follicular wall were subjectively scored on a 1-to-5 scale (1: no or very few blood flow; 5: intense blood flow detected in most of the follicular wall). The colour Doppler evaluations were performed retrospectively using videos recorded at each examination. The interval from treatment to ovulation was compared by Wilcoxon test. Differences in the vascularization score were compared considering the effects of treatment and time using the PROC MIXED procedure of SAS (SAS Institute Inc., Cary, NC, USA). As expected, in cows treated with EB, ovulations tended to occur earlier (48.0 ± 4.5 h v. 54.0 ± 7.1 h; P = 0.055) and were more synchronous (42–54 h, CV of 9.4% v. 42–66 h, CV of 13.3%) than in the control group. In both groups, follicular vascularization score progressively increased (P < 0.001) until ovulation. However, the vascularization score was lower (P < 0.05) in the EB group than in the control group during the 48-h period before ovulation (overall mean of 2.5 ± 0.7 and 3.0 ± 0.6, respectively); consequently, follicles of cows treated with EB ovulated with a lower vascularization score than did those in the control group (3.6 ± 0.5 v. 4.0 ± 0.5, respectively). Four cows (2 of each group) did not ovulate; follicle vascularization score in these cows remained below 2 during all the evaluation period. In conclusion, although an increase in blood flow is required for ovulation, EB-induced ovulations will occur and are associated with a reduced follicle vascularization. This difference may be related to the smaller interval from treatment to ovulation. Embrapa, CNPq, and Fapemig (CVZ PPM 0067/11) are acknowledged.

125 FOLLICULAR FLUID AND GRANULOSA CELL RECOVERY FROM BOVINE FOLLICLES OF DIFFERENT DIAMETERS USING AN ADAPTED TRANSVAGINAL-GUIDED FOLLICULAR ASPIRATION SYSTEM

Most studies of granulosa cell (GC) function have been performed in vitro, using follicular fluid (FF) and GC recovered from slaughterhouse ovaries. This approach does not consider the reproductive status and follicular developmental stage of the donor, limiting data interpretation and usefulness. The aim of this study was to evaluate the efficiency of an adapted ultrasound-guided transvaginal follicular aspiration (TVFA) procedure to recover FF and mural GC from live cows. A preliminary in vitro trial was performed to calculate fluid losses using a conventional TVFA circuit. A known volume of PBS, expected to be the volume of FF in follicles ranging from 4 to 12 mm in diameter, was aspirated using a 20 G needle connected to a Teflon circuit 80 cm long, with a 1.0-mm internal diameter, connected to a 1.5-mL tube. Losses of the expected volume of FF were 12.7 ± 1.1, 19.9 ± 2.5, 54.4 ± 4.0, 87.6 ± 4.3 and 100%, for follicles of 12, 10, 8, 6 and 4 mm in diameter (0.90, 0.52, 0.27, 0.11 and 0.03 mL, respectively). When an adapted system for small-volume recoveries was used, there was a decrease (P < 0.05) in fluid losses for follicles of 8, 6 and 4 mm. An experiment was performed in vivo, using the adapted system, to evaluate FF and GC recovery from follicles of 4 and 5 (n = 16), 6 (n = 19), 7 (n = 7), 8 (n = 13), 9 (n = 15), 10 (n = 24), 11 (n = 11), 12 (n = 15), 13 (n = 13), 14 (n = 6) and 16 (n = 9) mm in diameter. Follicular wave emergence was synchronized with 2 mg of oestradiol benzoate and an intravaginal progesterone device and follicles that reached the desired diameter were aspirated using an ultrasound machine equipped with a 7.5-MHz probe and disposable 20 G needle. The recovered FF volume was measured and centrifuged at 600 × g for 10 min. The GC pellet was vortexed with 0.1% hyaluronidase (5 min) and washed twice in PBS and the number of cells was determined using a Neubauer chamber. Ribonucleic acid was extracted using an RNAeasy Microkit and quantified in NanoDrop. The efficiency of FF recovery was estimated by the difference between the recovered and expected volumes for each follicle diameter (4/3πr3), which were compared by ANOVA. From all the follicles aspirated, the recovery of FF and GC was not successful in 2 (1.3%). Overall, FF recovery efficiency was 84.7%. The recovered volume ranged from 0.03 to 3.80 mL and increased with follicular diameter (y = 0.011x2 – 0.012x + 0.043; R2 = 0.99). Losses of FF were significant (P < 0.05) for follicles larger than 12 mm. The mean (±s.e.m.) number of mural GC recovered was 716,708 ± 68,536, providing 6.8 ± 0.7 samples of 100 000 cells with 14.8 ± 0.7 ng of RNA μL–1 for each punctured follicle. A high coefficient of variation (57.4%) was observed in cell recovery. There was no difference in the number of cells recovered from follicles of different diameters, but sample contamination with blood was more frequent (75%) in follicles larger than 10 mm. In conclusion, an adapted TVFA system can be used successfully on an individual basis and from follicles of different diameters for in vivo recovery of FF and GC for further endocrine and gene expression analyses. This research was supported by CNPq and Fapemig (CVZ APQ 02863/09).

20 ALTERED GENE EXPRESSION IN BOVINE SOMATIC CELL NUCLEAR-TRANSFERRED EMBRYOS AFTER TRICHOSTATIN A TREATMENT

Trichostatin A is a histone deacetylase inhibitor that improves histone acetylation and chromatin remodeling of somatic cell nuclear-transferred embryos (Iager et al. 2008 Cloning Stem Cells 10, 371–379; Maalouf et al. 2009 BMC Dev. Biol. 9, 11). We have previously observed that it also improves quality of bovine cloned embryos, which may increase pregnancy rates. This study aimed to evaluate the effect of trichostatin A treatment of zygotes on relative abundance of 9 transcripts in bovine nuclear-transferred blastocysts. In vitro matured oocytes were enucleated, fused to somatic cells and activated with ionomycin (Camargo et al. 2011 Reprod. Fertil. Dev. 23, 122). After activation, putative zygotes were randomly separated into 2 groups: NT-TRICHO, zygotes were cultured for 4 h in 6-DMAP followed by 7 h in CR2 aa medium plus with 2.5% fetal calf serum (FCS; Nutricell, Campinas, Brazil), both supplemented with 50 nM trichostatin A (Sigma); NT-CONT, zygotes were cultured in the same described conditions without thichostatin A supplementation. In vitro-fertilized embryos (IVF group) were used as a calibrator for relative transcript quantification. Embryos from the 3 groups were cultured in CR2 aa supplemented with 2.5% FCS under 5% CO2, 5% O2 and 90% N2 at 38.5°C. At 168 h postactivation, the embryos were rapidly frozen in liquid nitrogen. Pools of 10 blastocysts for each group were subject to RNA extraction and reverse transcription, in which cDNA was amplified by real-time PCR using the β-actin and GAPDH genes as endogenous references. The transcripts analysed encode high mobility group N1 (HMGN1), peroxiredoxin 1 (PRDX1), octamer-binding protein 4 (OCT4), insulin-like growth factor 1 and 2 receptors (IGF1r and IGF2r), glucose transporter 1 and 5 (GLUT1 and GLUT5), histone acetyltransferase (HAT) and heat shock protein 70.1 (HSP70) genes. Results were analysed by a pair-wise fixed reallocation randomization test using the REST software v.2. Data from NT-TRICHO and NT-CONT were compared with the IVF group and between themselves. The relative abundance of HSP70, PRDX1, IGF2r and HMGN1 transcripts was higher (P < 0.05) in NT-TRICHO compared with the IVF group and no difference was detected for the other transcripts. In the NT-CONT group, the relative abundance of IGF2r and HAT was higher (P < 0.05), whereas IGF1r and OCT4 were lower (P < 0.05) compared with IVF embryos. When data from NT-TRICHO and NT-CONT were compared, a higher amount (P < 0.05) of stress-associated transcripts (HSP70 and PRDX1) were found in NT-TRICO blastocysts. These results suggest that although trichostatin A may improve chromatin remodeling, alterations on gene expression still persist in bovine somatic cell nuclear-transferred blastocysts in comparison with IVF embryos. Financial support: Embrapa Project 01.07.01.002, CNPq 403019/2008–7 and Fapemig.

169 THE RELATIONSHIP BETWEEN OOCYTE RECOVERY AND EMBRYO PRODUCTION IN BOS INDICUS

The ovarian follicular population has been used as a parameter to evaluate fertility and also the potential of donors undergoing assisted reproductive procedures in both human medicine and animal practice. There is a high correlation between follicular population and oocyte recovery by ovum pickup (OPU), but the relationship between oocyte recovery, embryo production and pregnancy rates may not be fully understood. The aim of the present study was to evaluate whether the conversion rate of oocytes to embryos and further pregnancies could be positively related to the number of cumulus–oocyte complexes (COC) recovered after OPU in cattle. For this purpose, records of 626 OPU sections from 251 nonlactating Gyr cows (dairy Zebu breed) were analysed. The animals had a good body condition score, were kept in a good feeding pasture (Brachiaria spp.) and were supplemented with corn silage and a mixture of corn, soybeans and vitamin and minerals, according to their nutritional requirements. For each ovarian aspiration, the ovarian follicular wave was previously synchronized with an auricular implant (Norgestomet-Crestar®), IM injections of 2 mg of oestradiol benzoate (Gonadiol®) and 0.25 mg of D-cloprostenol (Sincrocio®). The OPU procedures were performed using an ultrasound device (Aquila Vet, Esaote, São Paulo, Brazil) equipped with a vaginal sector 7.5-MHz probe, disposable 20 G needles and a vacuum pressure of 80 mmHg. The cows were ranked in quartiles regarding the total number of COC recovered. To reduce bias related to the eventual fluctuation of OPU results, for the present analysis the authors used only the recorded OPU session of each cow with the highest number of COC recovered. Viable COC were fertilized with sex-sorted (X) semen of Gyr bulls previously tested for in vitro embryo production. Conversion rates (%) of the total and viable oocytes to embryos, viable oocytes to pregnancy and embryo to pregnancy were evaluated for each quartile. Differences between the first and fourth quartiles were accessed by Fisher's exact test. In the 251 OPU, 4246 total and 3173 viable COC were recovered, resulting in the production of 1001 embryos (31.5%) and 453 pregnancies (45.3%). The cows ranked in the first, second, third and fourth quartiles produced >30 (41.6 ± 10.6), 21 to 30 (25.2 ± 3.0), 12 to 20 (15.9 ± 2.6) and <12 (6.7 ± 3.1) total oocytes. The average viable oocyte (29.1 ± 11.0, 18.1 ± 5.3, 11.1 ± 3.7 and 4.5 ± 2.7, respectively) and embryo production (8.6 ± 5.7, 5.2 ± 3.6, 3.8 ± 2.8 and 1.8 ± 1.8, respectively) were different (P < 0.0001) among all quartiles. Pregnancy rates, however, did not differ (46.0, 44.9, 43.9 and 45.6%, respectively; P > 0.05). Interestingly, the conversion rates (viable oocytes to embryos and viable oocytes to pregnancies) were higher (P < 0.0001 and 0.002) in cows from the last quartile (51.1 and 31.9%) compared with those from the first quartile (23.7 and 14.7%). In conclusion, the number of COC recovered by OPU (and consequently the ovarian follicular count) can further predict the total number of embryos and pregnancies produced, but it is not directly related to the oocyte development potential. Biotran and Fapemig Project CVZ APQ 01654/09 and BPD 0007/10.

323 EFFICIENCY OF CLOPROSTENOL-INDUCED LUTEOLYSIS IN SUPEROVULATED COWS

The induction of multiple ovulations is a key procedure for in vivo embryo production. Many corpora lutea (CL) are developed, resulting in abnormally high progesterone concentrations. Luteolysis induction by prostaglandin F2α and its analogues is well described in cows bearing one or few, but not multiple, CL, as occurs after superovulation. The objective of the first experiment was to compare the efficacy of a single prostaglandin F2α treatment on inducing luteolysis in embryo donors immediately after flushing (D7, N = 24) or 4 days later (D11, N = 22). Holstein cows were superovulated with 400 IU of FSH following standard procedures. Embryo flushing was performed 7 days after AI, and cows were randomly allocated into 2 groups to receive either a 0.5 mg of sodium cloprostenol IM treatment immediately after flushing (D7 group) or the same treatment 4 days later (D11 group). Occurrence of luteolysis was monitored by plasma progesterone concentrations (P4), measured by radioimmunoassay in blood samples taken at 4-h intervals. There was no difference in P4 before treatment between D7 and D11 groups (28.6 ± 5.2 v. 36.4 ± 7.4 ng mL–1, respectively; P > 0.05). Although cloprostenol caused a remarkable decline in P4 48 h after treatment in both groups (1.8 ± 0.3 and 1.6 ± 0.4 ng mL–1 for D7 and D11 groups, respectively; P < 0.05), P4 continued decreasing in D11 cows thereafter, remaining smaller than 1 ng mL–1 up to 196 h after treatment, whereas in D7 cows, there was no further reduction in P4. Luteolysis (P4 <1 ng mL–1) was observed in all D11 cows, but failed in 11 of 20 (55%) D7 cows, in which P4 increased after the initial cloprostenol-induced decrease. The second experiment compared luteolysis in superovulated v. nonsuperovulated cows. Non-superovulated (control group, CG, N = 8) and superovulated cows (SOV, N = 6) received a single dose of sodium cloprostenol IM (0.5 mg) on day 11 after oestrus. Morphological and functional luteolysis were monitored daily by ovarian ultrasonography and P4 analysis; also, plasma LH was measured in blood samples taken every 20 min for 1 h, during 5 days. Individual CL size was smaller (1.8 ± 0.1 v. 3.5 ± 0.4 cm2) but total luteal tissue was greater (29.8 ± 7.0 v. 3.5 ± 0.4 cm2; P < 0.05) in SOV than in CG. A considerable decrease in P4 occurred in both groups 24 h after treatment (from 51.1 ± 12.9 to 5.1 ± 0.9 ng mL–1 in SOV and from 5.9 ± 0.6 to 1.1 ± 0.1 ng mL–1 in CG); however, SOV cows did not reach P4 values similar to CG until 96 h after treatment (0.9 ± 0.3 v. 0.4 ± 0.2 ng mL–1, respectively; P > 0.05). There was no difference in initial LH values between SOV and CG (1.5 ± 0.1 and 1.5 ± 0.1 ng mL–1; P > 0.05), but the slower decrease in P4 in the SOV group prevented LH from increasing up to 96 h after luteolysis induction, whereas mean LH values increased (P < 0.05) in CG after 24 h. In conclusion, luteolysis failure may occur when cloprostenol is given at the day of flushing (7 days after AI) in superovulated cows. In addition, luteolysis induction on day 11 after SOV is efficient, but the initial high progesterone concentration results in a slower rate of P4 decrease to basal levels. The authors acknowledge CNPq and FAPEMIG Project CVZ AQP 01654/09.

Pregnancy rates and corpus luteum-related factors affecting pregnancy establishment in bovine recipients synchronized for fixed-time embryo transfer

The objective was to investigate the influence of corpora lutea physical and functional characteristics on pregnancy rates in bovine recipients synchronized for fixed-time embryo transfer (FTET). Crossbred (Bos taurus taurus x Bos taurus indicus) nonlactating cows and heifers (n=259) were treated with the following protocol: 2mg estradiol benzoate (EB) plus an intravaginal progesterone device (CIDR 1.9g progesterone; Day 0); 400 IU equine chorionic gonadotropin (eCG; Day 5); prostaglandin F(2alpha) (PGF(2alpha)) and CIDR withdrawal (Day 8); and 1mg EB (Day 9). Ovarian ultrasonography and blood sample collections were performed on Day 17. Of the 259 cattle initially treated, 197 (76.1%) were suitable recipients; they received a single, fresh, quality grade 1 or 2 in vivo-derived (n=90) or in vitro-produced (n=87) embryo on Day 17. Pregnancy rates (23 d after embryo transfer) were higher for in vivo-derived embryos than for in vitro-produced embryos (58.8% vs. 31.0%, respectively; P<0.001). Mean (+/-SD) plasma progesterone (P(4)) concentration was higher in cattle that became pregnant than that in nonpregnant cattle (5.2+/-5.0 vs. 3.8+/-2.4 ng/mL; P=0.02). Mean pixel values (71.8+/-1.3 vs. 71.2+/-1.1) and pixel heterogeneity (14.8+/-0.3 vs. 14.5+/-0.5) were similar between pregnant and nonpregnant recipients (P>0.10). No significant relationship was detected between pregnancy outcome and plasma P(4), corpus luteum area, or corpus luteum echotexture. Embryo type, however, affected the odds of pregnancy. In conclusion, corpus luteum-related traits were poor predictors of pregnancy in recipients. The type of embryo, however, was a major factor affecting pregnancy outcome.

222 THE USE OF IN VITRO FERTILIZATION TO STUDY BOVINE IDIOPATHIC INFERTILITY

A 4-year-old beef bull underwent a breeding soundness evaluation at the Western College of Veterinary Medicine (Veterinary Hospital, University of Saskatchewan); no apparent abnormalities were observed after conventional semen evaluations. However, the clinical history of this bull indicated that no pregnancies resulted from natural service of 52 cycling cows over a period of 2 years. Completed services were observed. The objective of this study was to use in vitro fertilization (IVF) technology to evaluate whether the sperm from this infertile bull could successfully fertilize oocytes in vitro. Fresh semen was collected with an electroejaculator and frozen in a computer-controlled rate freezer. Concentration and motility parameters were assessed by using computer-assisted semen analyses. Sperm morphology was evaluated on eosin-nigrosin-stained slides, and Coomassie blue staining was used to evaluate the presence of intact acrosomes. Within each evaluation technique, frozen–thawed semen from bulls (n = 2) with proven fertility was used as a positive control and samples of dead sperm (produced by repeated frozen–thawed cycles until reaching no sperm motility) were used as a negative control. Frozen semen from the infertile bull was used for IVF assay. Data were analyzed by ANOVA (sperm motility and the presence of acrosomes) or the chi-square test (cleavage and blastocyst rates), with a P-value of 0.05. Our infertile bull showed an average motile sperm percentage of 91.7 ± 2.2%, with 78.6 ± 3.5% progressive motility. After cryopreservation procedures, frozen–thawed semen had an acceptable general and progressive percentage of motility of 57.8 ± 6.7% and 43.9 ± 9.2%, respectively. Sperm stained with Coomassie blue showed a greater proportion of intact acrosomes in the fresh semen (63.6 ± 4.3% v. 40.4 ± 3.7%; P < 0.05); however, frozen–thawed semen from both the fertile bull and the control were similar (40.4 ± 3.7b% v. 45.5 ± 2.2b%, P < 0.05). In vitro fertilization results revealed a low cleavage rate at 48 h postfertilization (19.8 ± 6.3%) and blastocyst rate (2.4 ± 2.8%) when using frozen–thawed semen from the infertile bull, compared with the control (56.7 ± 8.2% and 26.3 ± 4.5%, respectively; P < 0.001). Moreover, cleavage and blastocyst rates obtained by using the negative control (21.1 ± 3.2% and 1.1 ± 1.9%, respectively) were similar to those of the infertile bull (P > 0.10). It was noted that ova fertilized with either frozen–thawed semen from the infertile bull or the negative control did not produce blastocysts before Days 8 and 9 of embryo culture, which is a characteristic of parthenogenesis. The results from this IVF study suggest that in this bull, there was a missing or defective factor blocking one of the steps in the fertilization process. Further investigations to identify this factor will increase our knowledge of male fertility, and could lead to new methods of evaluating and regulating fertilizing ability.

313 ASSESSMENT OF LUTEAL FUNCTION IN TOGGENBURG GOATS BY COMPUTER-ASSISTED IMAGE ANALYSIS

Computer-assisted image analysis is a technological extension of reproductive ultrasonography and allows the quantitative assessment of the luteal echotexture, which is related to changes in histological features and, consequently, to steroidogenesis. The aim of this study was to determine the efficiency of luteal echotexture evaluation as a tool to assess luteal function in different phases of the estrous cycle in Toggenburg goats. Nulliparous goats (n = 21), 8 months in age, 33.52 ± 1.22 kg of body weight, and body score condition of 3.5 ± 0.07 (1 to 5 scale), which showed estrus within a 48-h period during the natural breeding season (March and April), were used. After estrous detection (Day 0) and mating, ovarian sonographic evaluations were performed daily using a portable ultrasound device (Aloka SSD 500, Aloka Co.) equipped with an adapted linear transrectal 5-MHz probe. The examinations were preceded by blood sample collections, which were stored until radioimmunoassay for progesterone (P4). Images were recorded in VHS tapes, then digitized to TIFF files (resolution of 1500 × 1125 pixels) using a video capture board. A representative elementary area of 5625 pixels (0.31 cm2) was defined for the luteal tissue according to the criterion proposed by Van den Bygaart and Protz 1999. Computer-assisted analyses were performed using custom-developed software (Quantporo®). Each pixel received a numeric value ranging from 0 (black) to 255 (white). Luteal echotexture and plasma P4 data were analyzed by ANOVA, and differences among means were determined by Tukey’s test. Correlations were established by Pearson’s correlation method. Results are shown as mean ± SEM. Corpora lutea size increased progressively (P < 0.001) until Day 9, when it reached the maximum area (1.26 ± 0.32 cm2). No increase in size was detected on the subsequent days (P > 0.05). Plasma P4 levels increased until a maximum value on Day 9 (6.31 ± 0.46 ng mL–1), and no increase was observed further (P > 0.05). In nonpregnant animals (n = 7), luteolysis was characterized by an abrupt decrease in plasma P4 concentration, which dropped to values lower than 1 ng mL–1 24 h after the onset of the process, whereas luteal area decreased gradually. Plasma P4 concentration was correlated to luteal area during luteogenesis and luteolysis (r = 0.63 and r = 0.50, respectively; P < 0.05). Mean pixel value showed a progressive increase during luteogenesis and reached the maximum value on Day 13 (54.33 ± 1.83). During corpus luteum (CL) regression, mean pixel value decreased to lower values 48 h after the onset of natural luteolysis (P < 0.05). Through both luteogenesis and luteolysis, positive correlations were observed between mean pixel values and luteal area (r = 0.34 and r = 0.26, respectively; P < 0.05) and also between mean pixel values and plasma P4 concentration (r = 0.24 and r = 0.37, respectively; P < 0.05). Pixel heterogeneity was not correlated to luteal area nor plasma P4 levels. These results suggest an association between CL echotexture and steroidogenic function; therefore, the quantitative assessment of the pixel brightness has a potential to be used for luteal function evaluation in goats. FAPEMIG and CAPES.

101 EFFECT OF DIETARY UREA ON EMBRYONIC VIABILITY AND DEVELOPMENT OF TOGGENBURG GOATS

Urea supplementation in the diet of ruminants may alter the pH and protein concentration in different tissues and may affect the embryo quality and viability. Imbalances in nitrogen metabolism during the periods of oocyte growth and/or fertilization may dispose the zygote, pre-implantation embryo, and surviving conceptus to developmental errors. The aim of this research was to investigate the effect of feeding urea to goats on embryo quality. Eighteen Toggenburg goats, 48.6 ± 7.9 kg of BW, 2.9 ± 0.5 BCS, and 34.3 ± 20.8 months of age, were allocated randomly to 2 treatments: T1 (control, n = 8): no urea, and T2 (n = 10): 2.4% of dry matter (DM) as urea in the diet. The animals were fed diets based on Coast-cross hay (Cynodon dactylon) and concentrate (14% crude protein, DM basis) for 42 ± 2 days before embryo flushing. Estrus was synchronized with intravaginal sponges impregnated with 60 mg of medroxyprogesterone acetate (Progespon®, Syntex S.A., Buenos Aires, Argentina) for 11 days plus i.m. injection of 100 μg of cloprostenol (Ciosin®, Schering-Plough, Cotia, Brazil), on the Day 9. The superovulation protocol consisted of i.m. injections of 200 mg equivalent of NIH-FSH-P-1 (Folltropin®, Bioniche, Athens, GA), in 6 decreasing doses at 12-h intervals, on Days 9, 10, and 11 (Day 0 = sponge insertion). Estrus was monitored twice a day for 30 min from sponge withdrawal by use of teaser bucks, and females were mated by fertile bucks every 12 h during standing estrus. Early luteal regression was preventing by administration of an antiluteolytic (Banamine®, Schering-Plough) 72 h after sponge withdrawal, 1.1 mg kg–1 per day i.m. for 3 days. Embryo recovery was done on the seventh day of estrous cycle by a transcervical technique. Recovered embryos were classified by quality (I = excellent, V = degenerated), development stage percent (1 = unfertilized oocytes, 9 = hatched blastocyst), and viability with the embryo grades 1 (excellent), 2 (good), and 3 (fair). The effect of urea supplementation on embryo stage and viability was analyzed by ANOVA. From the 18 goats, 12 (67%) were responsive to the superovulation protocol, 62.5% from T1 and 70.0% from T2. The number of embryos flushed (7.20 ± 2.39 v. 6.29 ± 2.93) and the percentage and number of viable embryos [100% (36/36) v. 100% (39/39)] from T1 and T2 were not different (P > 0.01). Thereafter, embryos in advanced stages of development (7, 8, and 9) were 58.65% from T2 compared with 0% from T1 (P < 0.01). In addition to the embryos, 13 unfertilized oocytes were recovered from the T2 goats v. none from the T1 goats (P < 0.01). These results suggest that urea may cause acceleration of embryo development and may affect oocyte fertilization. Supported by grants from CNPq, FAPEMIG, CAPES, Schering Plough®, Tecnopec®, and Carbogel®.

156 INVESTIGATION OF BOVINE HERPESVIRUS IN CUMULUS - OOCYTE COMPLEXES AND FOLLICULAR FLUID

The world market for bovine embryos has increased in the past few years. However, sanitary problems such as foot and mouth disease in Brazil, vesicular stomatitis in South America, and bovine spongiform encephalopathy (BSE) in North America and Europe have increased concerns regarding the risk of introducing exotic diseases and/or more virulent serotypes of endemic diseases by embryo transfer. Many countries are trying to develop and/or improve new techniques for infectious disease detection, with the scientific basis to support the import and export of animal germplasm. Therefore, the epidemiology of the diseases and the interaction between pathogens and cumulus–oocyte complexes (COCs), embryos, and semen must be investigated. Despite the many studies that have been carried out to evaluate the possibility of transmission of infectious agents by the embryo, few data are available regarding COC susceptibility (Tsuboi et al. 1992 J. Vet. Med. Sci. 54, 1179–1181). The aim of this study was to evaluate the presence of bovine herpes virus serotype 1 (BHV-1) in COCs and follicular fluid (FF) collected from naturally infected animals in a low stress condition. Blood samples of non-lactating Gyr breed (Bos indicus) cows were collected and evaluated for BHV-1 antibodies by the serum neutralization microplate test, performed as described in the Manual for Standards for Diagnostic Tests and Vaccines (OIE, 1992). The cows were diagnosed as serologically positive (n = 38) or serologically negative (n = 8), and kept under grazing in Brachiaria decumbens pasture with mineral supplementation. The cows considered as positive showed titers greater than 1/4. COCs and follicular fluid (FF) were obtained by ovum pick-up (OPU) using sterile and disposable materials for each animal. Virus detection was performed by the PCR technique. PCR sensitivity was made using COCs and FF recovered from eight BHV-1 serologically negative animals. These samples were either artificially infected on plates with 106.5 TCID in 50 µL of IBR Colorado 1 reference serotype (ATCC, VR-864) or used as a negative control. The PCR analitical sensitivity was 100.5 TCID. The presence of BHV-1 in COCs and FF was not detected in any of the animals, despite the high sensitivity of the PCR technique. In the present in vivo model, results show that COCs collected from serologically BHV-1 positive cows presenting no clinical signs of the illness and managed in a low stress condition could be used as donors for in vitro fertilization procedures with minimal sanitary risks. Also, the absence of the virus in COCs and FF cannot be used as a predictor of BHV-1 infection status in bovine herds.

315 CORPORA LUTEA MORPHOLOGICAL AND ECHOTEXTURAL ATTRIBUTES RELATED TO PLASMA PROGESTERONE CONCENTRATION IN HEIFERS

It has been suggested that ultrasound image attributes are a potential indicator of the physiological and functional status of the corpus luteum (CL). The aim of this study was to evaluate corpus luteum morphological and echotextural changes, and to correlate these changes with plasma progesterone concentration [P4] throughout the bovine estrous cycle. Crossbred heifers were scanned daily, using a B-mode, real-time ultrasound machine equipped with a 5-MHz linear-array rectal transducer, throughout a natural estrous cycle (Experiment 1; n = 12) or during a shorter estrous cycle, interrupted on the 10th day, by luteolysis induction (Experiment 2; n = 6). Blood samples were collected for further plasma [P4] analyses by RIA. Corpora lutea areas (cm2) were measured, and daily images of each CL were videotaped (VHS tapes) until digitized. Computer-assisted analyses of image attributes were performed using a custom-developed software. Daily values of luteal area, echotexture, and plasma [P4] values were analyzed by ANOVA with Tukey's test to determine differences among means of each cycle day. Pearson's correlation coefficients were calculated between luteal area, mean pixel value, pixel heterogeneity, and plasma [P4]. In the first experiment, luteal tissue area increased to a maximum on the 10th day (P < 0.05), followed by a plateau, and then declined from Day 14 to next estrus. There was a significant correlation between luteal tissue area and plasma P4 (r = 0.69; P < 0.01). In the second experiment, plasma P4 dropped to basal values 24 h after luteolysis induction. Luteal tissue area decreased at a slow rate, and reached values similar to ones from metestrus 36 h after treatment. In Experiment 1, echotexture parameters of the CL were analyzed after data adjustment to the onset of luteolysis. In both experiments, mean pixel values did not change throughout the estrous cycle and there was no correlation between mean pixel values and plasma [P4] (P > 0.10). Pixel heterogeneity changed throughout the natural estrous cycle, with maximum value on metestrus (Day 14; Day 0 = luteolysis) and minimum on diestrus (Day 2; P < 0.01). However, this parameter did not change when luteolysis was induced (Experiment 2; P > 0.10). There were significant correlations between pixel heterogeneity and plasma progesterone in both of the experiments (r = –0.69 and r = –0.48; P < 0.05). In conclusion, mean pixel values do not reflect morphological or functional changes of the CL throughout the estrous cycle. On the other hand, based on the correlations between pixel heterogeneity and systemic [P4] in both experiments, this image attribute (heterogeneity) has the potential to indicate functionality and steroidogenic capacity of the luteal gland.

312 LUTEAL MORPHOMETRIC PARAMETERS AND SONOGRAPHIC ECHOTEXTURE DURING LUTEOGENESIS PERIOD IN PREGNANT GOATS

Sonographic echotexture is an important parameter for corpora lutea (CL) evaluation, since it is related to variations on vascularization and histological features of CL and, consequently, to steroidogenesis. The aim of this study was to evaluate the luteal dynamics and pixel value during the early luteogenic period in goats. Nuliparous Toggenburg females (n = 18) with an average age of 8 months, weight of 33.52 � 5.58 kg, and body condition score of 3.5 � 0.33 (1 to 5 scale) were used. Ovarian sonographic evaluations were performed daily for 21 days after natural estrus, using a portable ultrasound device (Aloka SSD 500, Aloka Co., Ltd., Tokyo, Japan) equipped with an adapted linear rectal 5-MHz probe. CL and cavity areas were measured at their largest diameter. CL area minus the cavity area was considered luteal tissue. Images were digitalized in .TIFF format, at a 1500 � 1125 resolution, using a video capture board (Pinnacle DC10, Pinnacle Systems, Mountain View, CA, USA). Images recovered on Days 6, 8, 10, and 12 of the estrous cycle were analyzed using a custom software (Quantpro�). Each image dot (pixel) received a numeric value ranging from 0 (black) to 255 (white). Representative elementary area (REA) of 5625 pixels (0.31 cm2) was defined in the luteal tissue (proposed by Van den Bygaarty et al. 1999 Can. J. Soil Sci. 7, 149–160). Due to the possibility of early luteal regression, only data from pregnant animals (14/18, 77.8%) were used. Follicle diameter, CL area, and cavity were analyzed by ANOVA, and differences among means were evaluated by Tukey's test. Correlations were established by Pearson's correlation method. Results are presented as means � SEM. Mean diameter of ovulatory follicle was 0.75 � 0.01 cm. There was no significant correlation (P > 0.05) between ovulatory follicle diameter and CL area. CL were first visualized on Day 5.68 � 0.37 after the estrus, with a mean area of 0.56 � 0.05 cm2, and progressively increased in size (P < 0.001) until Day 12, reaching a maximum area of 1.18 � 0.06 cm2. A significant (P < 0.05) pixel value increase was observed from Days 6 to 12 of the cycle (42.79 � 5.06a; 47.90 � 4.51ab; 48.33 � 4.21b; and 52.95 � 4.65b, respectively, values with the same superscript not being significantly different). There was a significant positive correlation (R = 0.54, P < 0.0001) between luteal tissue area and pixel value during the luteogenesis period. In single ovulating goats (10/14; 71.42%), the mean time for the first CL visualization was lower (4.71 � 0.15 v. 6.78 � 0.89 days; P < 0.01) and the area of the CL on Day 12 was larger (1.32 � 0.04 v. 1.03 � 0.15 cm2; P < 0.01) than in goats with two or more ovulations, but there was no difference in luteal pixel value (52.32 � 3.19 v. 53.75 � 3.90; P > 0.05). The presence of luteal cavities was observed in 89.47% (17/19) of the CLs on the first day of visualization, with a mean size of 0.30 � 0.05 cm2, representing 45.31% of the total CL area and difficult echotexture analysis. These cavities progressively regressed (P < 0.01) until Day 11 of the cycle, with an area less than 0.1 cm2. These results show that pixel values are correlated to CL development in goats, suggesting an association between CL echotexture and steroidogenic function.

392 CHARACTERISTICS OF THE SUPEROVULATORY RESPONSE IN GYR (BOS INDICUS) CATTLE

Gyr is the most important zebu breed for dairy herds in Brazil and in other tropical countries. Superovulatory responses in this breed have been shown to be lower than in European or beef zebu breeds such as Nelore and Brahman. The aims of this study were to investigate the effect of the presence of a dominant follicle on the superovulatory response, and to determine endocrine patterns in superstimulated and non-superstimulated Gyr cows. The first experiment was designed to evaluate the effect of the dominant follicle on embryo yield. Multiparous, non-lactating Gyr cows were treated with a conventional superovulation (SOV) protocol [300 IU of Pluset (Serono, Roma, Italy) in 8 decreasing doses] starting on either Day 10 (G10, n = 14) or Day 8 (G8, n = 16) of the estrous cycle or 48 h after dominant follicle removal by ultrasound-guided follicle aspiration (G48, n = 10). Ovarian follicle populations were monitored daily by ultrasonography. Data were analyzed by ANOVA, and means were compared by Tukey&apos;s test. Dominant follicle removal resulted in a larger number of small follicles before SOV (27.1 &plusmn; 2.7 vs. 14.7 &plusmn; 1.5 and 13.1 &plusmn; 1.2; P &lt; 0.05), but the number of follicles reaching a diameter larger than 9 mm after superstimulation (17.4 &plusmn; 1.3 vs. 14.4 &plusmn; 2.0 and 11.4 &plusmn; 2.0; P &gt; 0.05), and the number of viable (IETS grades 1 and 2) embryos (3.1 &plusmn; 0.8 vs. 3.0 &plusmn; 0.7 and 3.3 &plusmn; 0.8; P &gt; 0.05) did not differ from G10 and G8 groups, respectively. There was great variation in superovulatory response, and the Pearson correlation between follicle numbers at the time of initiating superstimulatory treatments and response was low (r &equals; 0.49; P &gt; 0.05). In the second experiment, endocrine patterns in superstimulated (n &equals; 32) and non-superstimulated (n &equals; 24) Gyr cows were compared. Blood samples were collected on Day 14 of the estrous cycle or after 4 days of FSH treatment when follicular fluid was also obtained from both groups by ultrasound-guided follicle aspiration. Plasma and follicular fluid samples were stored at &minus;20&deg;C until assay for progesterone (P4), androstenedione (A2), and estradiol (E2) by RIA, using commercial kits (MedLab, Auckland, New Zealand, and Diagnostic Systems Laboratories, Inc., Webster, MN, USA). Mean plasma E2 concentrations did not differ between FSH-treated and control cows (3.7 &plusmn; 0.4 vs. 3.2 &plusmn; 0.4 pg mL&minus;1; P &gt; 0.05). Intrafollicular concentrations of E2, A2, and P4 in FSH-stimulated follicles (mean size of 14.0 &plusmn; 1.2 mm) were 193.5 &plusmn; 83.0, 55.7 &plusmn; 17.0, and 54.8 &plusmn; 28.1 ng mL&minus;1, respectively, lower (P &lt; 0.05) than those found in non-superstimulated growing dominant (mean size of 11.6 &plusmn; 0.5 mm) follicles (501.2 &plusmn; 83.8, 122.2 &plusmn; 22.5, and 97.0 &plusmn; 21.9 ng mL&minus;1, respectively), but similar to concentrations in non-superstimulated, non-dominant (mean size of 7.2 &plusmn; 0.4) follicles (152.6 &plusmn; 99.2, 37.7 &plusmn; 20.3, and 37.3 &plusmn; 6.8 ng mL&minus;1 for E2, A2, and P4, respectively). Results suggest that factors other than follicle dominance adversely affect superovulatory responses in the Gyr breed, and that follicular steroidogenesis may also be adversely affected following treatment with exogenous FSH. Results also failed to support the use of ultrasonography to predict superovulatory response in the Gyr breed.

415 USE OF COMPUTER-ASSISTED ULTRASOUND IMAGE ANALYSIS IN EMBRYO RECIPIENT SELECTION

Ultrasonography has been extensively used in the study of reproductive function in areas such as antral follicular dynamics, ovulation, luteal function, and early pregnancy. However, most studies with ultrasound evaluation are limited to measurement of diameter, length, or area of internal structures, and few groups use differences in image density (echotexture) as an evaluation parameter. For corpora lutea, echo-texture differences reflect variations in vascularization and luteal cell proportions. The aim of the present study was to evaluate image analysis as a tool for embryo recipient selection. Grades I or II embryos produced by conventional superovulation (n = 55) or IVF (n = 87) were nonsurgically transferred to primiparous cows or heifer recipients (n = 142). Estrous synchronization was performed using the heat-synch protocol (Day 0: CIDR�; Day 5: 400 IU of eCG; Day 7: 500 �g of cloprostenol plus CIDR removal; Day 9: 2 mg of estradiol benzoate). Sonographic corpora lutea images were obtained on the day of embryo transfer (Day 7), using a portable ultrasound device (Aloka SSD 500; Aloka Co., Sao Paulo, Brazil) equipped with a linear rectal 5 MHz probe. Images were digitalized in .TIFF format at a resolution of 1500 � 1125, using a video capture board (Pinnacle DC10; Pinnacle Systems, Mountain View, CA, USA). A representative elementary area (REA) of 2.704 pixels (25 mm2) was defined in the luteal tissue, using the criteria proposed by Van den Bygaart et al. (1999 Can. J. Soil Sci. 79, 149–160). Image analysis was performed using a custom software package (QuantPro�). Each image dot (pixel) received a numeric value ranging from 0 (black) to 255 (white). Data from cows and heifers later diagnosed as pregnant or not in the groups receiving SOV or IVF embryos were analyzed by ANOVA, and results are presented as means � SEM. As expected, the pregnancy rate was higher for conventional than for IVF embryos (58.2% vs. 31.0%; P &lt; 0.05). There was a low correlation (R = 0.33) between luteal tissue area and pixel value for Day 7 corpora lutea. There was no difference (P &gt; 0.05) in luteal tissue area or echotexture between pregnant and non-pregnant animals in the groups receiving superovulation embryos (3.12 � 0.26 cm2 vs. 2.63 � 0.25 cm2, and 78.03 � 2.25 vs. 79.73 � 3.73, respectively) and IVF embryos (3.25 � 0.24 cm2 vs. 3.03 � 0.14 cm2, and 74.81 � 1.93 vs. 70.82 � 1.62, respectively). However, in the IVF embryo group, no pregnancy was established in cows bearing a CL with mean pixel value lower than 60.25 or greater than 89.27 (total values ranged from 44.72 to 99.79). Corpora lutea image analysis, using the REA proposed in this approach, had limited value to predict pregnancy rate of embryo recipients. Further studies will investigate the accuracy of the REA established and other image characteristics, including the pixel distribution pattern.