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.

Early resynchronization of non-pregnant beef cows based in corpus luteum blood flow evaluation 21 days after Timed-AI

The study aimed to verify whether a hormone protocol started at Day 13 (D13) after Timed Artificial Insemination (TAI) influences the conception rate. Nelore cows (primiparous and multiparous) from two commercial beef farms (n = 1,431) were first TAI (D0). Timed AI was performed in lots (TAI Lots) ranging from 187 to 346 cows. On D13, regarding the TAI lot, cows were assigned for either receiving (Resynch group, n = 1,002) or not (Control group, a subset of approximately 30%, n = 429) another hormone protocol for resynchronization. The same hormone protocol was used for the first TAI and for the resynchronization, except for 1 mg instead of 2 mg of estradiol benzoate (EB) at the begging of the protocol. Eight days later (D21), the Resynch group was checked for corpus luteum blood flow by color Doppler ultrasonography, and in those detected as non-pregnant, the protocol was completed and a 2nd TAI was performed at D23. Pregnancy diagnosis was later (D30) performed by B-mode ultrasonography in the control group and confirmed in the presumptive pregnant cows from the 1st TAI of the Resynch group. The remaining cows were checked for pregnancy 30 days after the 2nd TAI (experimental Day 53). The statistical model to explain conception rate considered the effects of Group (Control or Resynch), Farm, Parity (primiparous or multiparous), Sire, Technician (who perform AI), TAI Lot and pertinent interactions (Group*Parity, Group*Farm and Group*TAI Lot). The statistical analyses of the model were performed using the Proc Glimmix (SAS virtual University Edition). The conception rate for the 1st TAI was similar (P > 0.4) between Control (50.3%, 216/429) and Resynch group (52.6%, 527/1002). The positive predictive diagnostic on D21 showed high relation with PD30 (90.7%, 527/581). In Resynch group, non-pregnant cows (n = 421, 1002 minus 581) were re-inseminated. The conception rate of the 2nd TAI (42.8%, 180/421) was affected (P < 0.002) by side effects of the Farm (48.5 vs. 33.1%) and Parity (51.2 vs. 40.3%, for multiparous vs. primiparous, p < 0.001). Nevertheless, after the 2 TAIs of the Resynch group, the cumulative conception rate was 70.5% (707/1002). In conclusion, the early resynchronization of cows with a low (1 mg) EB dose and progesterone device at D13 after TAI can be used as a strategy to reduce conception interval in beef cattle, and thus to increase the number of pregnant cows from artificial insemination after the breeding season.

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.

149 EFFECT OF RESVERATROL ANALOGUE ON DEVELOPMENT OF IN VITRO-FERTILIZED BOVINE EMBRYOS

Oxidative stress is one of the main effects of in vitro culture. Generation of reactive oxygen species (ROS) by embryos can be enhanced by the sub-optimal in vitro culture conditions and are associated with a delay in embryonic development. However, supplementation of culture medium with antioxidant agents can minimize the effects of ROS (Guérin et al. 2001 Hum. Reprod. Update 7, 175–189). Resveratrol is an example of a potent antioxidant, and modifications in its structure can improve its biological activity. This study evaluated the effect of AR33 (formula with patent pending), an analogue of resveratrol with high antioxidant activity, on embryo development. Bovine cumulus-oocyte complexes recovered from ovaries collected at the slaughterhouse were in vitro matured for 24 h and oocytes were in vitro fertilized for 20 h, both at 38.8°C under 5% CO2 in air and high humidity. Partially denuded presumptive zygotes were randomly distributed in 4 treatments (with 6 replicates): 0 µM (control, n = 347), 0.1 µM (n = 337), 0.5 µM (n = 277), and 2.5 µM (n = 343) of AR33. The base medium was SOFaa supplemented with 2.5% FCS and incubation conditions were 38.8°C under 5% CO2 in air and high humidity. Half of culture medium was renewed (feeding) at Day 3 and 5 post-fertilization. Cleavage was evaluated at Day 3 and blastocyst rates at Day 7 and 8 post-fertilization. Data were analysed by logistic regression considering the significance level of P < 0.05. Values are shown as mean ± SEM. Cleavage rate was higher (P < 0.05) for 2.5 µM (69.0 ± 4.4%) than for 0, 0.1, and 0.5 µM AR33 (62.1 ± 2.0%, 60.7 ± 5.9%, and 56.7 ± 5.8%, respectively). At Day 7, the blastocyst rate was similar (P > 0.05) among 0.1, 0.5, and 2.5 µM (18.1 ± 5.4%, 17.5 ± 2.9%, and 19.4 ± 3.3%, respectively) and all of them were higher (P < 0.05) than 0 µM AR33 (12.4 ± 2.5%). At Day 8, there was again no difference (P > 0.05) among 0.1, 0.5, and 2.5 µM AR33 (21.0 ± 5.0%, 18.4 ± 2.1%, and 24.6 ± 3.3%, respectively) but only 0.1 and 2.5 µM showed higher (P < 0.05) blastocyst rate than 0 µM AR33 (15.2 ± 2.5%). In conclusion, the synthetic analogue of resveratrol tested in this study can improve bovine embryo development in culture medium supplemented with 2.5% FCS under 5% CO2 in air. A concentration of 2.5 µM AR33 can be a choice for further studies. This study was supported by Fapemig, CAPES, and CNPq.

Corpus luteum blood flow evaluation on Day 21 to improve the management of embryo recipient herds

The aim of the present study was to use blood flow evaluation of the CL at 14 days after embryo transfer to detect nonpregnant animals and optimize the management of bovine recipients. The estrous cycle was synchronized in 165 recipients, and the day of expected ovulation was considered to be Day 0. Embryo transfer was performed 7 days later, on Day 7. On Day 21, pregnancy was diagnosed on the basis of blood flow evaluation of the CL (DG21-predictive diagnostic). To validate this methodology, visual scores for blood flow were compared to objective data extracted from CL ultrasound images recorded in the Doppler mode. The size was also evaluated using recorded images of the CL in the B mode. Blood samples were also collected for further analysis of the progesterone (P4) concentration. The diagnosis of pregnancy was confirmed at 35 days after estrus (DG35-definitive diagnostic). The DG21 showed that 55.2% (90 of 163) of the animals were presumptively pregnant, and this value was higher (P < 0.04) than that obtained at DG35 (43.6%, 71 of 163). The predictive diagnostic achieved moderate specificity (79.3%) for the detection of pregnancy, but most importantly, high sensitivity (100%) for the detection of nonpregnant recipients. The overall accuracy of the diagnosis was 88.3%. The P4 concentrations were different (P < 0.02) and correlated with each visual score assigned for the CL size. Visual scores for CL blood flow were also efficient (P < 0.0001) to distinguish animals with different levels of P4; however, P4 concentrations were higher for scores 1 and 2 (high and regular blood flow, respectively) than those for score 3 (low blood flow). This technique showed high sensitivity and facilitated the early detection of nonpregnant animals. The DG21 would allow about 79.3% of nonpregnant animals to be resynchronized 9 to 14 days earlier, when compared to conventional management based on pregnancy diagnosis at Days 30 to 35.

99 EFFECT OF SEASON AND WEIGHT GAIN ON PREGNANCY RATES OF EMBRYO RECIPIENTS RAISED UNDER PASTURE CONDITIONS

In most Brazilian farms, the management of embryo recipients is done exclusively under grazing systems. Thus, the seasonal variation of grass availability can affect the energy balance and reduce weight gain, and consequently affects the rate of pregnancy. The aim of the present study was to evaluate the effect of the seasonal variation of daily weight gain (DWG) on the pregnancy rate of crossbred heifers (Bos taurus × Bos indicus). The study was performed in the southwest region of Minas Gerais State, Brazil, during one year. Two periods were evaluated: dry (April to September, average precipitation of 470 mm and low grass availability) and rainy (October to March, average precipitation of 1930 mm and high grass availability) seasons. The recipients were kept in a grazing system (Brachiaria brizantha) with water and minerals available ad libitum. Embryos were produced in vitro by the same laboratory, using oocytes and sex-sorted semen from the Gir breed (Bos indicus). A total of 404 fresh embryos (N = 484, 45.4% during dry and 54.5% during rainy season) were transferred by the same technician on Day 7 days of the oestrous cycle – synchronized with prostaglandin – of the recipients, which were weighted at the day of embryo transfer and 23 to 25 days later, at the diagnostic of pregnancy. Animals were retrospectively allocated into 4 groups according to the DWG observed between embryo transfer and pregnancy diagnosis: G1 (N = 132) up to 150 g; G2 (N = 132) between 151 and 250 g; G3 (N = 119) between 251 and 350 g; and G4 (N = 99) greater than 350 g of DWG. The pregnancy rates were compared among DWG groups and between seasons by chi-squared. The logistic regression model was performed using the PROC GENMOD to test the model, including the effects of DWG, season, and the interaction (DWG × season). During the dry season, there was change in frequency distribution of the heifers among DWG groups, with lower frequency (P < 0.05) of heifers in high (G3 and G4) when compared with low (G1 and G2) DWG groups (33.2, 31.4, 21.8, and 13.6% for G1, G2, G3, and G4, respectively). Altogether, pregnancy rate was not different between dry and rainy seasons (42.3 v. 45.8%, respectively; P > 0.05). When compared to G1, pregnancy rate was higher (P < 0.05) for recipients with daily weight gain greater than 250 g day–1 (G3 and G4) (35.6, 40.6, 52.1, and 51.0% for G1, G2, G3, and G4, respectively). Only the effect of the DWG was significant in logistic regression, and the odds rate for each gram of DWG was 0.0039, which means that pregnancy rate improved 1.17 times for recipients with 300 g of DWG. In conclusion, the DWG after embryo transfer, but not the season itself, affect pregnancy rate of in vitro-produced embryo recipients. Biotran, FAPEMIG, and CnPQ are acknowledged.

124 IDENTIFICATION OF LUTEINIZING HORMONE RECEPTOR ISOFORMS DURING FOLLICLE DEVELOPMENT IN CATTLE

The expression of the LH receptor (LHR) is required for the transition from FSH to LH-dependence during the establishment of follicular dominance in cattle. The aim of this study was to identify LHR isoforms expressed before, during, and after follicle deviation, using as models dairy breeds with different dominant follicle sizes at deviation. Mural granulosa cells (GC) were collected using an adapted ultrasound-guided follicular aspiration system (Arashiro et al. 2012 Reprod. Fertil. Dev. 24, 175) from follicles of 6, 8, 10, or 12 mm in diameter of Holstein (Bos taurus), and of 4, 6, 8, or 10 mm of Gir (Bos indicus) heifers. The recovered follicular fluid was centrifuged and the cells were washed with NaCl 0.9% saline and kept in RNA Later (Ambion). Total RNA extraction was performed from GC using a commercial RNeasy Micro Kit (Qiagen), quantified in a spectrophotometer (Nanodrop), and reverse transcribed using the commercial Superscript III kit (Invitrogen). The generated cDNA were PCR amplified using a specific primer for the LHR and designed to detect a region of known occurrence of isoforms. The samples were previously tested for theca cell contamination using a primer to detect the CYP17A1 gene, and those showing contamination were excluded. Results of PCR were analysed by electrophoresis in 5% native acrylamide gel. The frequency of occurrence of the different isoforms was compared by the chi-squared test. In Holstein, the full-length form of the LHR mRNA (459 bp) was detected in all samples. The isoform with total deletion of exon 10 and partial of exon 11 (isoform II; 113 bp) was observed in 4 of 6 follicles of 6 mm and in 4 of 5 follicles of 8 mm. The isoform with total deletion of exon 10 (isoform III; 378 bp) was observed in 4 of 6 follicles of 6 mm, and in all follicles of 8 mm (5/5). The isoform with partial deletion of exon 11 (isoform IV; 194 bp) was observed in 4 of 6 follicles of 6 mm and in 4 of 5 follicles of 8 mm. These 3 alternative isoforms were present in all follicles of 10 mm (4/4) and 12 mm (11/11). There was no difference (P > 0.05) in the frequency of occurrence of the different isoforms. In Gir, the expression of LHR was less regular, no isoform was present in all samples, and no follicle size class showed all isoforms. The full-length LHR mRNA was detected in 2 of 7 follicles of 4 mm, 6 of 9 follicles of 6 mm, 2 of 6 follicles of 8 mm and in all follicles of 10 mm (6/6). The isoform II was observed in 3 of 7 follicles of 4 mm, 3 of 9 follicles of 6 mm, 2 of 6 follicles of 8 mm, and in all (6/6) follicles of 10 mm. The isoform III was observed in 6 of 7 follicles of 4 mm, 7 of 9 follicles of 6 mm, and in all follicles of 8 mm (6/6) and 10 mm (6/6). The isoform IV was observed in 5 of 7 follicles of 4 mm, 6 of 9 follicles of 6 mm, 5 of 6 follicles of 8 mm, and in 5 of 6 follicles of 10 mm. In the Gir breed, the isoform with deletion of exon 10 was the most frequent one (P < 0.01). More than one isoform was observed in most samples. In conclusion, 1) LHR is expressed in GC before follicle deviation, and 2) the expression of LHR isoforms is affected by follicle diameter and breed. The authors acknowledge support from CNPq 477701 and Fapemig PPM 0067/11.

115 FOLLICULAR GROWTH AND BLOOD FLOW OF THE DOMINANT FOLLICLE IN CROSSBRED RECIPIENTS TREATED WITH eCG

This study aimed to explore changes in follicle diameter and blood flow of the dominant follicle (DF), in ovulation and embryo transfer rates, after inclusion of eCG in a protocol for timed embryo transfer. The effect presence or absence of a corpus luteum (CL) at the start of treatment was also included. Crossbred heifers (n = 116, Bos taurus × Bos indicus), with (n = 61) or without (n = 55) CL, were included in the same hormone protocol: Day 0 (D0), insertion of progesterone (P4) device (1.0 g, Sincrogest®, Ouro Fino, São Paulo, Brazil) and 2 mg of oestradiol benzoato (EB, Sincrodiol®, Ouro Fino); D8, removal of P4 device and injection of sodium Cloprostenol (0.250 mg mL–1, Sincrocio®, Ouro Fino). On D8, the animals with and without CL – at the beginning of the protocol – were equally divided into 2 groups (G): G1 – injection of 300 IU (2.0 mL) of eCG (n = 56; Synchro eCG®, Ouro Fino); G2 – 2.0 mL of saline (n = 60). The ovulations were synchronized with 1 mg of EB on D9. From D8 to D11, the diameter of the DF and blood flow in its wall were recorded daily (M5 ultrasound with colour Doppler technology, 7.5-MHz linear array, DPS medical equipment, São Paulo, Brazil). Approximately 100 frames in colour-flow mode, containing entire cross-sections of the DF, were recorded during each examination. The area of the follicular wall with coloured pixels was measured with ImageJ software (Image Processing and Analysis in Java) from the frame with the largest blood flow signal. Before embryo transfer, all heifers were evaluated, and those with good-quality CL received frozen/thawed embryos (ethylene glycol 1.5 mol). Follicle diameter and blood flow area were compared between groups with or without CL before timed embryo transfer protocol and between eCG treatments. The PROC GLM procedure of SAS (version 9.0) and the t-test were used to assess the differences between means. Pregnancy diagnosis was performed on D35. Embryo transfer (ET) rate of the recipients and pregnancy rate were compared between CL or eCG treatments by the chi-squared test. Ovarian status, before hormone protocol, did not change (P > 0.05) the follicular growth of the DF. However, ovulation rate (78.8 v. 65.4%, P < 0.05) and ET rate (78.7 v. 65.4%, P < 0.05) were higher in animals with CL on D0. From D8 to D10, the inclusion of eCG did not affect (P > 0.05) follicular growth and blood flow of the DF. The time effect (P < 0.0001) for follicular blood flow had shown an increase in area of blood flow 24 h after implant removal (7.7 ± 0.7,b 10.2 ± 0.7,a and 12.3 ± 1.0a mm2, for Days 8, 9, and 10, respectively). The eCG did not affect (P > 0.05) the ovulation rate (71.4 and 73.3%, respectively, eCG and no eCG), however, approached an increased (P < 0.06) ET rate (78.8 v. 66.7%). The overall pregnancy rate (51.2%, 43/84) was not affected (P > 0.05) by evaluated variables. In summary, the addition of 300 IU of eCG on D8 of the timed embryo transfer protocol did not change the development of DF but increased the ET rate of the recipients. Biotran, FAPEMIG (project number APQ-1454-12), and CnPQ are acknowledged.

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.

Efficiency of the spermatogenesis in zebu bulls (Bos taurus indicus)

The objective of the research was to evaluate the efficiency of the spermatogenesis through the morphology of the testicular parenchyma in bulls of different zebu breeds. We used testicular fragments from bull of the breeds Nelore (n = 10), Polled Nelore (n = 6), Gyr (n = 5), Guzerat (n = 5) and Tabapuã (n = 5). The tissue was perfused with Karnovsky solution, included in glycol methacrylate and stained with toluidine blue-sodium borate 1%. Animals of the Nelore breed presented higher population of primary spermatocyte in pre-leptotene/leptotene (38.30) and in pachytene (38.14) and round spermatids (113.30), higher yield of spermatogonia mitosis (21.2) and higher daily spermatic production per gram of testicular parenchyma (32.8 × 10(6) ) than those from breeds Gyr, Guzerat and Tabapuã and higher general yield of spermatogenesis (62.4) than breeds Gyr and Tabapuã. There was no significant difference in any of the evaluated parameters between breeds Nelore and Polled Nelore. The rate of Sertoli cells did not vary between the studied breeds. Apparently, the genetic selection applied to the breeds has been improving the yield in the spermatogenic process by decreasing cellular loss, although it did not increase the support capacity of the Sertoli cells.

228 IN VITRO EMBRYO PRODUCTION AFTER EXPOSURE OF BOVINE OOCYTES TO DIFFERENT TRANSPORTATION MEDIA AND PERIODS: PRELIMINARY RESULTS

This study was designed to evaluate the effect of different oocyte transportation media and time. Immature oocytes were recovered from slaughterhouse bovine ovaries. Oocytes (n = 492) of quality grades I to III were randomly allotted to one of the following transportation media based on TCM-199, either buffered with HEPES (control) or buffered with NaHCO3 and added with FSH/LH (maturing). Both media were supplemented with pyruvate, penicillin G (10 000 IU), streptomycin (0.05 mg mL–1), and 10% fetal bovine serum (FBS). In control medium, the oocytes were kept for 1 or 8 h at 37°C, and thereafter were transferred to maturing medium until the maturation period (24 h) was completed, under controlled atmosphere (5% CO2) and temperature, in an incubator. The maturing oocytes were distributed in two types of equipment developed for oocyte and embryo transportation, with and without 5% CO2, and kept for 1, 8, or 24 h before maturation or fecundation (IVF) procedures. The oocytes kept for 24 h in the transportation device were placed directly for IVF. All procedures used for in vitro maturation, IVF, and in vitro culture were the same as those adopted for commercial in vitro embryo production at Biotran LTDA (Alfenas, Minas Gerais, Brazil). The cleavage rate was evaluated on Day 3 post-insemination, and the blastocyst production was evaluated on Day 7. The statistical model included the main effects of treatment (control and maturing with or without 5% CO2), time, replicate, and the interaction of media × time. Data (3 replicates) were analysed by ANOVA and differences were identified by Tukey’s test. The time before in vitro maturation at the incubator negatively (P < 0.007) affected cleavage rates (76.4 ± 16.9 v. 58.8 ± 13.2 and 52.2 ± 18.5%, respectively, for 1, 8, and 24 h). However, treatment had no effects (P = 0.3) on cleavage (66.9 ± 15.0, 57.8 ± 19.7, and 67.7 ± 19.8% for the control and maturation with and without 5% CO2, respectively). Similarly, blastocyst production rates differed (P < 0.04) between 1 h (33.4 ± 14.7) and 24 h (19.3 ± 17.0%), whereas blastocyst production at 8 h did not show significant effects (19.3 ± 17.0). Although it was not significant (P > 0.05), only 14.1% of the oocytes kept in medium 2 with a controlled atmosphere for 24 h became embryos. This difference was probably related to the trend in treatment effect (P = 0.06) and the lower rate of embryo production (22.2 ± 13.6%) in this treatment compared with the control (33.8 ± 18.1%) and maturation without 5% CO2 (29.8 ± 17.3%). These results showed that 24 h of transportation is detrimental for the oocyte development potential and that the buffered medium used in this study with 5% CO2 did not efficiently maintain embryo production. Supported by CNPq, CAPES, FAPEMIG, and Biotran LTDA.

110 PREGNANCY RATES OF BOVINE EMBRYOS AND HEMI-EMBRYOS TRANSFERENCE

Embryo transfer (ET) in cattle speeds up genetic gains, but its use is limited by cost-benefit analysis. In addition other techniques can be developed, such as sexing and bipartition of embryos. An alternative to improve the economic viability of ET in cattle would be to bipartition embryos in order to increase the yield of the technique. The aim of this study was to investigate the operational viability of embryo bipartition technique in an ET program in cattle and to study aspects related to the viability and development of bovine hemi-embryos (HE) compared with intact ones. The embryos were collected by nonsurgical technique 7 days after the onset of oestrus. Viable structures (130) from 49 embryo collections from 25 Aberdeen and Simmental donor cows and heifers were used. Only embryos in compact morula, early blastocyst and blastocyst stage, with a morphological range from excellent to good grade (IETS Grade 1), were split. The embryos, split (78) or not (52), were transferred into the uterine horn ipsilateral to the corpus luteum of the recipients 7 days after oestrus. The treatment groups evaluated were T1 (intact embryo, n = 52), T2 (1 HE, n = 27) and T3 (2 HE, n = 51). Crossbred heifers were used as recipients and pregnancy diagnosis was done at 60 to 80 days of gestation. The embryos of T1, T2 and T3 were classified morphologically as excellent or good and by developmental stage as morula, early blastocyst, or blastocyst, distributed as follows: T1: 30, 22 and 16, 17 and 19; T2: 15, 12 and 7, 9 and 11; and T3: 29, 22 and 15, 15 and 21, respectively. The birth rate per original embryos was greater for T2 than for T1 and T3 (Table 1). The pregnancy rates for excellent and good embryos and morulae, early blastocysts and blastocysts were not different (P > 0.05). The T1, T2 and T3 twin births were 0, 1 and 5, respectively. It is concluded that embryo bipartition technique applied in a commercial ET program is a viable operational technique. Table 1.Pregnancy at 60 to 80 days and birth rate per original embryos used Supported by CAPES, CNPq, FAPEMIG and BIOTRAN.

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.

287 EFFECT OF FOLLICULAR WAVE SYNCHRONIZATION AND ABSENCE OF CORPUS LUTEUM ON COC RECOVERY IN Gyr (BOS TAURUS INDICUS) COWS

Transvaginal guided follicle aspiration (TGFA) is the main technique used in Brazil to recover oocytes for in vitro embryo production (IVP) in bovine. Different protocols have been proposed to synchronize follicular emergence in oocyte donors, but most of them were developed for use in European breeds of cattle, which show many differences in ovarian physiology when compared with Zebu breeds. The aim of this study was to compare different protocols for preparation of Gyr (dairy zebu breed) oocyte donors. The TGFA were performed in a donor management facility located in Minas Gerais State, southeast Brazil. Pluriparous cycling Gir cows (n = 42) were used as donors. All cows underwent 3 treatments: G1 (control), no treatment before TGFA; G2, 2 mg of estradiol benzoate (EB) for follicular wave synchronization given i.m. 5 days before TGFA; and G3, norgestomet auricular implants given 9 days and 2 mg of EB plus 0.53 mg of cloprostenol given 5 days before TGFA. The interval between TGFA in the same donor was greater than 30 days. All procedures were made by the same technician, using a portable ultrasound device, disposable 19G or 20G needles, and a vacuum pressure of 80 mm Hg. The aspirated follicular fluid was collected in 50-mL Falcon tubes and sent to the laboratory for COC identification and classification under 50 × magnification. Recovered oocytes were classified according to cumulus cell layers and cytoplasm morphology. The total number of oocytes and viable COC recovered and the procedure length (min), including time spent for TGFA and laboratory manipulation, were compared. Data were evaluated by ANOVA, and means compared by Tukey’s test. A total of 126 TGFA sessions were performed, with recovery of 2,809 oocytes (20.31 ± 12.32 of COC and 14.83 ± 7.97 of viable COC per cow/session; mean ± SD). The total number of recovered oocytes and viable COC recovered were lower in G1 compared with G2 and G3 (15.18 ± 11.07 v. 21.18 ± 9.71 and 24.68 ± 9.03; and 9.53 ± 7.22 v. 16.97 ± 6.47 and 18.84 ± 8.90, respectively; P < 0.05) There was no difference (P > 0.05) between G2 and G3 on the number of oocytes or viable COCs recovered. The procedure length, however, was longer in G1 and G2 compared with G3 (49.6 ± 15.1 and 46.9 ± 13.4 v. 35.8 ± 13.1 min, respectively; P < 0.05) The shorter procedure length in G3 was probably associated with the reduced number of cows showing no corpora lutea (38/42, 90%), which resulted in reduction of bleeding and clot formation in the aspirated fluid. These results show that (1) previous follicular wave synchronization by EB can improve the number and quality of recovered oocytes; (2) the absence of corpora lutea does not increase the number of recovered COC and viable COC, but reduces the time spent in the procedure. Intervet Schering Plough Animal Health.

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.

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.

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.

219 RETROSPECTIVE ANALYSIS OF CUMULUS - OOCYTE COMPLEX YIELD INA GYR (BOS TAURUS INDICUS) HERD UNDERGOING TRANSVAGINAL ULTRASOUND-GUIDED FOLLICLE ASPIRATION

Bovine in vitro embryo production (IVP) is extensively used in Brazil, associated with transvaginally guided follicle aspiration (TGFA). The good results obtained with the use of TGFA-IVP in this country are related to the ovarian physiology characteristics of zebu breeds, which include a lower persistence of dominant follicles and a greater number of follicles emerging in each follicular wave. There are, however, few reports of COC yield in these breeds in large-scale TGFA-IVP systems. The aim of this study was to analyze data on COC recovery from a Gyr (dairy zebu breed) herd in Brazil. Only pluriparous, nonlactating cows were used as donors. Follicle aspiration was performed with a portable ultrasound device, using disposable 19- or 20-gauge needles and a vacuum pressure of 80 mmHg. The follicle population before TGFA was recorded, and recovered oocyes were classified according cumulus cells layers and cytoplasm aspect. Data were analyzed by ANOVA, and means were compared by Tukey's test. Associations between variables were analyzed by Pearson's correlation method. A total of 761 TGFA sessions were performed in 54 donors, with the recovery of 8082 oocytes (10.62 � 0.32 per session) and 6208 viable COC (8.19 � 0.25 per session). Each donor underwent from 1 to 42 TGFA sessions. Both the number of total oocytes and viable COC were highly correlated with the number of follicles present in the ovaries (mean of 15.81 � 0.32) in the moment of TGFA (R = 0.86 and R = 0.83, respectively, P < 0.0001). There was a significant donor effect (P < 0.0001) in the mean number of follicles in the ovaries (ranging from 4.50 � 0.65 to 37.50 � 2.50), oocytes (from 0.75 � 0.48 to 30.50 � 8.50), and viable COC (from 0.75 � 0.48 to 25.67 � 6.12) recovered. The absolute maximum and minimum values for these parameters were 74, 67, and 44 v. 3, 0, and 0, respectively. The TGFA order also affected all parameters evaluated (P < 0.0001), with a linear decrease in the number of follicles punctured (y = –0.22x + 18.64, R2 = 0.65), total oocytes ( y = –0.25x + 13.81, R2 = 0.68) and viable oocytes (y = –0.22x + 11.05, R2 = 0.77) recovered. This decrease was probably associated with the cumulative damage in ovarian structure, once all parameters were affected, although from the first to the second TGFA session the mean number of oocytes (20.09 � 1.70 v. 14.08 � 1.11) and viable COC (16.37 � 1.27 v. 11.83 � 1.04), but not of aspirated follicles (22.28 � 1.60 v. 19.38 � 1.19), were reduced (P < 0.05). The decline in oocyte yield was greater ( y = –0.71x + 10.45, R2 = 0.95) when considering donors undergoing TGFA continuously (within intervals shorter than 8 days). Overall bastocyst rate was 28.48%, with a significant correlation between COC recovered and embryos produced (R = 0.64, P < 0.0001). These results shows that (1) follicular population is the main characteristic affecting the number of recovered COC, and consequently IVP; (2) the great variability in follicular population and in COC recovery among donors allows the selection of animals for IVF; and (3) repeated TGFA negatively affect ovarian follicle emergence and COC recovery.

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.