Conceptus-induced changes in the gene expression of blood immune cells and the ultrasound-accessed luteal function in beef cattle: how early can we detect pregnancy?

Protein Synthesis by Day 16 Bovine Conceptuses during the Time of Maternal Recognition of Pregnancy

Interferon Tau (IFNT), the conceptus-derived pregnancy recognition signal in cattle, significantly modifies the transcriptome of the endometrium. However, the endometrium also responds to IFNT-independent conceptus-derived products. The aim of this study was to determine what proteins are produced by the bovine conceptus that may facilitate the pregnancy recognition process in cattle. We analysed by mass spectrometry the proteins present in conceptus-conditioned media (CCM) after 6 h culture of Day 16 bovine conceptuses (n = 8) in SILAC media (arginine- and lysine-depleted media supplemented with heavy isotopes) and the protein content of extracellular vesicles (EVs) isolated from uterine luminal fluid (ULF) of Day 16 pregnant (n = 7) and cyclic (n = 6) cross-bred heifers on day 16. In total, 11,122 proteins were identified in the CCM. Of these, 5.95% (662) had peptides with heavy labelled amino acids, i.e., de novo synthesised by the conceptuses. None of these proteins were detected in the EVs isolated from ULF. Pregnancy-associated glycoprotein 11, Trophoblast Kunitz domain protein 1 and DExD-Box Helicase 39A were de novo produced and present in the CCM from all conceptuses and in previously published CCM data following 6 and 24 h. A total of 463 proteins were present in the CCM from all the conceptuses in the present study, and after 6 and 24 h culture in a previous study, while expression of their transcripts was not detected in endometrium indicating that they are likely conceptus-derived. Of the proteins present in the EVs, 67 were uniquely identified in ULF from pregnant heifers; 35 of these had been previously reported in CCM from Day 16 conceptuses. This study has narrowed a set of conceptus-derived proteins that may be involved in EV-mediated IFNT-independent embryo–maternal communication during pregnancy recognition in cattle.

Applied use of interferon-tau stimulated genes expression in polymorphonuclear cells to detect pregnancy compared to other early predictors in beef cattle

We aimed to evaluate the accuracy of Interferon-tau stimulated genes (ISG) abundance in peripheral blood polymorphonuclear cells (PMNs) on D20 after fixed-time artificial insemination (FTAI; D0) as a pregnancy diagnosis method against CL evaluation by Doppler ultrasonography and progesterone (P4) concentrations on D20, as well as Pregnancy Associated Glycoproteins (PAG) concentrations on D25. Additionally, we evaluated the potential of ISG abundance in PMNs as pregnancy loss predictors. Nelore heifers (n = 103) and cows (n = 144) underwent estrous synchronization and were artificially inseminated on D0. Pregnancy was diagnosed by B-mode ultrasonography on D30 and D70, and after the final diagnosis, females were classified in four groups: Pregnant; Non-pregnant; Functional CL on D20 but non-pregnant (CL-NP) and Pregnancy loss between D30 and D70 (PL). After determining cutoff values, the Sensitivity (SE), Specificity (SP), Positive Predictive Value (PPV), Negative Predictive Value (NPV) and Accuracy (ACC) were determined for each method. All methods were classified as significant (P < 0.05) predictors of pregnancy. Both ISG expression and PAG concentrations were greater (P < 0.05) in pregnant females than in non-pregnant and CL-NP females but did not differ (P > 0.05) from the PL group. ISG15 expression was greater (P < 0.05) in heifers than in cows, but this difference was not found in OAS1 expression and PAG concentrations. All the methods evaluated were proven to be adequate predictors of pregnancy, but greater accuracies were obtained through PAG concentrations and Doppler-US, due to the decreased number of false positive and false negative results.

Roadmap to pregnancy in the first 7 days post-insemination in the cow: Immune crosstalk in the corpus luteum, oviduct, and uterus

The first 7 days post-insemination are critical for establishment of pregnancy. The pre-ovulatory luteinizing hormone (LH) surge induces ovulation through disruption of the follicle structure that elucidates pro-inflammatory (Th1) responses. Various types of immune cells are recruited into the corpus luteum (CL) to regulate luteal angiogenesis and progesterone (P4) secretion into the circulation to establish pregnancy. The active sperm-uterine crosstalk also induces Th1 responses, mainly via Toll-like receptor (TLR) 2/4 signaling pathway in vitro. The endometrial glands serve as sensors for sperm signals, which trigger Th1 responses. Conversely, the sperm-oviduct binding generates anti-inflammatory (Th2) responses to support sperm survival until fertilization. It is well-established that embryo-maternal crosstalk starts after the embryo hatches out from the zona pellucida (ZP). However most recently, it was shown that the 16-cell stage bovine embryo starts to secrete interferon-tau (IFNT) that induces Th2 immune responses in the oviduct. Once developing embryos descend into the uterine horn, they induce Th2 responses with interferon-stimulated genes (ISGs) expression in the uterine epithelium and local immune cells mainly via IFNT release. Likewise, multiple embryos in the uterus of superovulated donor cows on D7 post-insemination induce Th2 immune responses with ISGs expressions in circulating immune cells. These findings strongly suggest that the maternal immune system reacts to the embryo during the first 7 days post-insemination to induce fetal tolerance. It became evident that the innate immunity of the developing CL, oviduct, and uterus works together to provide optimal conditions for fertilization and early embryonic development during the first 7 days post-insemination.

Oxytocin-induced prostaglandin F2-alpha release is low in early bovine pregnancy but increases during the second month of pregnancy†

Circulating prostaglandin F2α metabolite (PGFM) after an oxytocin challenge was evaluated throughout the first 2 months of pregnancy in lactating Holstein cows. On day 11, 18, and 25 after artificial insemination (AI), and on days 32, 39, 46, 53, and 60 of pregnancy, cows were challenged with 50 IU oxytocin, i.m. Blood was collected before (0 min), 30, 60, 90, and 120 min after oxytocin for plasma PGFM concentrations. Ultrasound evaluations were performed for pregnancy diagnosis on day 32-60 post-AI. Nonpregnant (NP) cows on day 18 were designated by a lack of interferon-stimulated genes in peripheral blood leukocytes and Pregnant (P) based on day 32 ultrasound. On day 11, P and NP were similar with low PGFM and no effect of oxytocin on PGFM. On day 18, oxytocin increased PGFM (3-fold) in NP with little change in P cows. Comparing only P cows from day 11 to 60, basal circulating PGFM increased as pregnancy progressed, with day 11 and 18, lower than all days from day 25 to 60 of pregnancy. Oxytocin-induced PGFM in P cows on day 25 was greater than P cows on day 18 (2.9-fold). However, oxytocin-induced PGFM was lower on day 25 compared to day 53 and 60, with intermediate values on day 32, 39, and 46 of pregnancy. Thus, the corpus luteum (CL) of early pregnancy (day 11, 18) is maintained by suppression of PGF, as reflected by suppressed PGFM in this study. However, during the second month of pregnancy, uterine PGF secretion was not suppressed since basal PGFM and oxytocin-induced PGFM secretion were elevated. Apparently, mechanisms other than suppression of oxytocin receptors maintain CL after day 25 of pregnancy.

Increased pregnancy rate in beef heifers resynchronized with estradiol at 14 days after TAI

We aimed to evaluate the treatment with estradiol benzoate (EB) or 17β-estradiol (E2) associated with progesterone (P4) for resynchronization of ovulation 14 days after timed artificial insemination (TAI). In Experiment 1 (Exp. 1), Nelore heifers were submitted to TAI (D0). On D14, the animals received an intravaginal P4 device and were randomly assigned to one of three groups: control (no treatment; n = 17); EB (1  mg EB; n = 17); and E2+P4 (1 mg E2 + 9 mg P4; n = 18). Ultrasonography evaluations were performed daily from D14 to D22 to map follicular and luteal dynamics. On D22, the P4 devices were removed and non-pregnant (NP) animals were determined using corpus luteum blood flow Doppler ultrasonography. In Exp. 2, 1295 beef heifers were resynchronized and randomly allocated to the same experimental groups as described in Exp. 1. On D22, the largest follicle (LF) was measured in NP and a second TAI was performed on D24. In a subset of heifers (n = 337), an estrus detection patch was used between D22 and D24 to monitor estrus expression and the LF was measured at D24. Confirmatory diagnosis of pregnancy was performed between D37-67 and D43-67 after first and second TAI, respectively. In Exp 1, the proportion of heifers with a synchronized follicular wave emergence (from 3 to 5 days after treatment) was greater (P < 0.05) in the EB group (93.8%) than in the control (62.5%) and E2+P4 (64.7%) groups. Structural luteolysis occurred earlier (P < 0.05) in the EB and E2+P4 groups than in the controls. The pregnancy rate after first TAI did not differ (P > 0.1) among the groups at D22 and at confirmatory diagnosis in both experiments. In Exp 2, the potential pregnancy loss between D22 and D37-67 was similar (P > 0.1) in the control (19% [36/185]), EB (15% [28/182]) and E2+P4 (15% [28/184]) groups. The LF diameter (mm) on D22 was greater (P < 0.05) in the control group (11.9 ± 0.1) than in EB (11.3 ± 0.1) and E2+P4 (11.5 ± 0.1). No difference (P > 0.1) was observed in the proportion of heifers detected in estrus, but LF growth rate (mm/day) between D22 and D24 was greater (P < 0.05) in EB group (0.9 ± 0.08) than in control (0.6 ± 0.07) and E2+P4 (0.7 ± 0.09) groups. The pregnancy rate for the second TAI was greater (P < 0.05) in the EB group (47% [94/200]) than in the control (37% [76/203]), but did not differ (P > 0.1) from the E2+P4 group (43% [93/214]). In conclusion, the treatment with 1 mg EB or 1 mg E2 + 9 mg P4 at 14 days post-TAI anticipates luteolysis in NP heifers but does not compromise pregnancy. The EB treatment induces a new synchronized follicle wave emergence and increases the pregnancy rate of resynchronized NP heifers.

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.

Maternal nutrient restriction in early pregnancy increases the risk of late embryo loss despite no effects on peri-implantation interferon-stimulated genes in suckler beef cattle

Reducing feeding costs in suckler beef herds to improve economic returns could have detrimental impacts on fertility. This study sought to determine whether maternal nutrient restriction during early pregnancy affects interferon-stimulated gene (ISG) expression in peripheral blood mononuclear cells during the peri-implantation period in two beef cattle breeds. Relationships were also examined between subnutrition and pregnancy failure defined according to ISG fold changes on Days 18 and 21 and to plasma pregnancy specific protein B (PSPB) concentrations on Day 28 post-artificial insemination (AI). Pirenaica or Parda de Montaña dams were assigned to a control (n = 23) or subnutrition (n = 30) group, receiving 100% or 65% of their estimated nutritional requirements from Day 1 to 82 post-AI, respectively. Treatment did not affect ISG expression or fertility. According to ISG fold changes (chi-square P = .023) or PSPB levels (chi-square P = .04) recorded in the subnutrition group, late embryo loss was more likely than in controls. Positive correlation was detected between Day 28 PSPB concentrations and both Day 18 MX1, MX2 and ISG15 expression, and Day 21 OAS1 expression. OAS1 and MX1 fold changes were found to be the best variables to discriminate pregnancy status. Our findings indicate that maternal nutrient restriction during the first third of pregnancy does not impair embryo signalling yet may increase the risk of pregnancy failure.

Early Pregnancy Induces Expression of STAT1, OAS1 and CXCL10 in Ovine Spleen

Interferon-tau is a maternal recognition factor in ruminant species, and spleen plays an essential role in regulating innate and adaptive immune responses. However, it is not fully understood that early pregnancy induces expression of interferon stimulated genes (ISGs) in the spleen during early pregnancy in ewes. In this study, spleens were collected from ewes at day 16 of the estrous cycle, and on days 13, 16, and 25 of gestation (n = 6 for each group), and RT-qPCR, western blot and immunohistochemistry analysis were used to detect the expression of signal transducer and activator of transcription 1 (STAT1), 2',5'-oligoadenylate synthetase 1 (OAS1), myxovirusresistance protein 1 (Mx1) and C-X-C motif chemokine 10 (CXCL10). The results revealed that STAT1, OAS1 and CXCL10 mRNA and proteins were upregulated in the spleens during early pregnancy, and STAT1 protein was located in connective tissue cells in the capsule and trabeculae, and blood cells and lymphocytes in the red pulp. However, early pregnancy had no significant effects on expression of MX1 mRNA and protein. In conclusion, early pregnancy induces expression of STAT1, OAS1 and CXCL10 in maternal spleen, suggesting that maternal spleen is involved in immune regulation of pregnancy in sheep.

Symposium review: Predicting pregnancy loss in dairy cattle

Several tools exist to diagnose pregnancy in dairy cattle. However, substantial pregnancy loss occurs within the first 60 d of gestation in cattle, and these losses have a profound adverse economic impact on the dairy and beef cattle industries. Detecting these impending pregnancy losses could offer producers an opportunity to reduce costs associated with this source of reproductive inefficiency. Several of the pregnancy diagnostic tools currently available and new technologies are being examined for their ability to predict pregnancies at risk for failing in early pregnancy. This review provides a synopsis of work undertaken recently to predict pregnancy losses in cattle. Currently, opportunities to predict pregnancy loss include (1) using transrectal ultrasonography to detect loss of the fetal heartbeat, floating debris within the placental fluids, and reductions in fetal size; (2) observing reductions in circulating progesterone concentrations; (3) detecting reductions in concentrations of circulating placental products; namely, pregnancy-associated glycoproteins and microRNAs; and (4) detecting reductions in the early pregnancy-dependent increase in interferon-stimulatory gene expression in peripheral blood leukocytes. An achievable goal may be to identify markers of embryo mortality so that researchers and clinicians can focus their efforts on developing intervention strategies for cows identified to be at risk for pregnancy failure.

Early pregnancy diagnosis at 21 days post artificial insemination using corpus luteum vascular perfusion compared to corpus luteum diameter and/or echogenicity in Nelore heifers

The objective was to compare the use of corpus luteum (CL) vascular perfusion to CL diameter and/or echogenicity to diagnose pregnancy at 21 d after timed-AI. Ovaries of Nelore heifers were assessed using ultrasonography in B-mode and color Doppler simultaneously 21 d after timed-AI (n = 113). Objective evaluations were performed using an image processing software to extract the number of colored pixels (ColorPix), diameter (mm) and echogenicity/mm² (EchoPix) of the CL. Subjective evaluations of the CL were performed by five evaluators using scores of estimated vascular perfusion area of color Doppler scan videos and estimated CL size and qualitative echogenicity of B-mode scan videos. The reference pregnancy diagnosis was performed 33 d after timed-AI using an ultrasonic device. Corpus luteum ColorPix, diameter and EchoPix were highly correlated (P < 0.001) with pregnancy. Pregnancy diagnosis accuracy, sensitivity, and negative predictive value were not different for CL ColorPix and diameter and was less with use of EchoPix compared to the other parameters. Size and vascular perfusion scores were correlated to the greatest extent (0.88-0.94) with the respective objective values within evaluator. The results from the ROC curve analysis indicated a smaller area under the curve for qualitative echogenicity compared to CL size and vascular perfusion. Corpus luteum vascular perfusion was the only subjective evaluation that when assessed there were no false negative pregnancy diagnoses. In conclusion, the use of the objective CL diameter resulted in the same efficacy as CL vascular perfusion evaluations for early pregnancy diagnosis in Nelore heifers.

Progesterone Supplementation During the Pre-implantation Period Influences Interferon-Stimulated Gene Expression in Lactating Dairy Cows

This study examined the effect of progesterone (P4) supplementation from Days 16 to 18 post-AI on interferon-stimulated gene (ISG) expression on Day 19 in high-producing dairy cows. Gene expression levels were measured in peripheral blood mononuclear cells. Possible relationships between ISG expression and the incidence of pregnancy failure were also investigated. Cows were alternately assigned on Day 16 post-AI to a control (C: n = 13) or treatment group (P4: n = 14). Out of 27 cows, 12 returned to oestrus before pregnancy diagnosis and 9 were diagnosed as pregnant on Day 28. ISG expression was assessed in all cows. Expression levels for the genes OAS1, ISG15, MX1 and MX2 were higher for pregnant than for non-pregnant cows (P=0.04; P<0.001; P=0.02; P=0.045; respectively). A significant (P=0.01) interaction was observed between the treatment and positive pregnancy diagnosis groups on Day 28 post-AI for the probability of showing ISG expression. This interaction suggests that in cows not pregnant on Day 28, P4 supplementation may have led to increased ISG15 mRNA expression on Day 19. Lower ISG15 expression was detected for cows returning to oestrus than for pregnant cows (P<0.001). However, cows with a negative pregnancy diagnosis showed intermediate values, differences being non-significant when compared to cows returning to oestrus or pregnant cows. Our results suggest that P4 supplementation during the pre-implantation period promotes conceptus signalling.

Accuracy of subjective evaluation of luteal blood flow by color Doppler ultrasonography for early diagnosis of pregnancy in Egyptian buffalo

The objective of the current study was to evaluate the accuracy of trans-rectal color Doppler ultrasonography for early diagnosis of pregnancy in Egyptian buffalo based on subjective assessment of luteal blood flow (LBF). After timed artificial insemination (TAI), a total of 112 pluriparous buffalo were subjectively evaluated for LBF and there were score scales or grades (I-IV) determined at different times (Days 6, 14, 17, 21) post-TAI. Another trans-rectal B-mode ultrasonography of the uterus was performed at Day 35 to confirm pregnancy diagnosis based on recognition of the positive signs of pregnancy. Retrospectively, the results of B-mode ultrasonography were compared to that of the subjective evaluations of LBF for determining accuracy values. Furthermore, serum progesterone (P4) concentrations were determined as an indicator of corpora lutea (CL) function. Results indicate 68 of 112 buffalo (60.7%) were diagnosed as pregnant. The accuracy value of the LBF subjective evaluation was significant (80.4%; P <  0.05) at Day 17, and there was the maximum accuracy (96.4%) at Day 21 post-TAI. The percentage of false diagnoses was less at Days 17 and 21 compared with Day 6 and 14 post-TAI. There was a significant matching value between P4 concentrations and scores for LBF on and after Day 17 post-insemination. In conclusion, subjective evaluation of LBF using color Doppler ultrasonography is considered an accurate technique for early detection of pregnancy in Egyptian buffalo especially the non-pregnant animals as early as Day 17, with maximum accuracy at Day 21 post-TAI.

Supplementation with long-acting progesterone in early diestrus in beef cattle: II. Relationships between follicle growth dynamics and luteolysis

The aims were to characterize follicular dynamics in response to supplemental progesterone (P4) and to investigate the relationships between follicular growth and onset of luteolysis in P4-treated cows, submitted or not to artificial insemination (AI). Nonsuckled beef cows detected in estrus were assigned to receive AI or to remain non-AI. Three days after ovulation (ie, D3), AI cows were injected with 150 mg of long-acting P4 (AI + injectable P4 formulation [iP4]; n = 22), and the non-AI cows were assigned to receive 150 mg iP4 (n = 19) or saline (control, n = 19). Between D3 and D21, growth dynamics of the dominant follicles (DFs) was monitored by ultrasonography. Plasma P4 concentrations were measured every other day from D9 to D19. Pregnancy status (ie, P: pregnant and NP: nonpregnant) was examined by ultrasound on D28 to D32. Injectable P4 formulation supplementation decreased average maximum diameter of first-wave DF (DF1). Neither day of emergence of DF2 or DF3 nor the proportion of two- or three-wave cycles were altered by supplemental P4. Daily mean diameter of DF2 and DF3 was also similar between control and iP4 groups. Consistently, daily mean diameter of DF1 in iP4-treated cows was smaller for cows that underwent luteolysis by D15 compared to a later onset. Progesterone concentrations between D9 and D19 decreased earliest in the iP4 group, latest in the control group and was intermediate for the NP-AI + iP4 group. In addition, three-wave cycles presented a delayed decrease on plasma P4 concentrations than two-wave cycles. Further analysis revealed that on two-wave cycles, P4 concentrations on D15 were lowest in the iP4 and NP-AI + iP4 animals compared to the control and P-AI + iP4 groups. Conversely, for three-wave cycles, on D15, P-AI + iP4, NP-AI + iP4, and controls had greater P4 concentrations than the iP4 group. In summary, our data indicate that impairment of first follicular growth was associated with P4-induced shortened luteal lifespan (D14-D15) and that three-wave cycles after AI can be more supportive for pregnancy maintenance in P4-treated cows. We speculate that such conditions play a critical role in the embryonic ability to inhibit iP4-induced early luteolysis reported in part I of this series.

An objective volumetric method for assessment of ovarian follicular and luteal vascular flow using colour Doppler ultrasonography

Our goal was to develop an objective computer-assisted volumetric method of assessing vascular flow from colour Doppler ultrasound data of ovarian structures recorded by free-hand movement. We hypothesized that a vascularity index (ratio of the region of blood flood to the region of ovarian structure) obtained from the three-dimensional volumetric analysis would be more precise (less variable) than conventional two-dimensional analysis of single images in estimating the functional status of the preovulatory follicles and corpus luteum. Doppler ultrasound cineloops of water buffaloes (Bubalus bubalis; n = 22) ovaries were recorded daily from 12 h before GnRH treatment to four days after ovulation. Cineloops were processed using Fiji and Imaris software packages for segmenting the area (two-dimensional analysis) and the volume (three-dimensional analysis) occupied by the blood-flow and associated tissue to calculate the vascularity index. For volumetric measurement, all images in a cineloop were used (i.e., no a-priori selection of images) while for two-dimensional analysis, three images from the region with apparent maximum vascularity were selected. The volumetric method was verified with theoretical ellipsoidal volume of the follicle (r = 0.96 P < 0.01) or corpus luteum (r = 0.58 P = 0.02). The variability in the follicular vascularity index among animals was lower using the volumetric method than two-dimensional analysis (0.018 ± 0.002 vs 0.030 ± 0.005, P < 0.01), while the variability for CL vascularity was similar between methods (P = 0.23). An increase in the follicular vascularity index was detected at 12 h after GnRH treatment using both methods (two-dimensional: 0.030 ± 0.008, P < 0.01; three-dimensional: 0.016 ± 0.006, P < 0.02). Buffaloes that ovulated tended to have a greater increase in 3D vascularity index than non-responding buffaloes (P = 0.06); the two-dimensional method was not able to detect these changes. Using the three-dimensional method, a moderate positive correlation (r = 0.59; P = 0.02) was evident between the follicular vascularity index at 14-16 h after GnRH treatment and follicular diameter. In conclusion, an objective volumetric method for assessing relative ovarian blood flow changes was developed using Doppler ultrasound cineloops recorded by free-hand movement. The 3-dimensional method eliminates the need for a-priori selection of images and is more precise as a result of decreased technical variability.

A novel strategy for resynchronization of ovulation in Nelore cows using injectable progesterone (P4) and P4 releasing devices to perform two timed inseminations within 22 days

We aimed to evaluate the reproductive performance of Nelore lactating cows submitted to a resynchronization 12 days after timed artificial insemination (TAI) with or without a long-acting progesterone (P4-LA) treatment. Nelore cows were submitted to a P4/oestradiol-based TAI protocol (D0 = insemination). On D12, cows in the control group (n = 184) received a new P4 intravaginal device (0.96 g), whereas cows in the P4-LA group (n = 192) received the P4 device and 75 mg P4-LA. Cows identified as non-pregnant (n = 120) by regression of corpus luteum using colour Doppler ultrasonography on D20 had the P4 device removed and received 500ug of sodium cloprostenol, 1 mg of oestradiol cypionate and 300 IU of eCG and were re-inseminated on D22. There was no difference (p > 0.10) in the pregnancy rate at D20, D30 and D60 after first TAI between the control (69%, 59.7% and 57%, respectively) and P4-LA (67%, 55.7%, and 55.2%, respectively) groups. Pregnancy losses were similar between both groups (p > 0.1). For cows submitted to the second TAI, the pre-ovulatory follicle size did not differ (p > 0.1), but the oestrous detection and pregnancy rates were greater (p < 0.05) in the P4-LA group (92.2% [59/64] and 60.9% [39/64], respectively) than in controls (75% [42/56] and 44.6% [25/56]). The cumulative pregnancy rate after two TAIs did not differ (p > 0.1) between control (73.3% [135/184]) and P4-LA (76% [146/192]) groups. The use of P4-LA at 12 days after TAI potentially increases the pregnancy rates for a new early resynchronization strategy associated with the Doppler imaging for pregnancy diagnosis and results in an alternative to perform two TAIs in 22 days in beef cows.

Duplex Quantitative Polymerase Chain Reaction of ISG15 and RSAD2 Increases Accuracy of Early Pregnancy Diagnosis in Dairy Cows

Early diagnosis of pregnancy is important in livestock production, but there is no reliable technology used for pregnancy diagnosis within the first three weeks after insemination. During early pregnancy, the expression of interferon-stimulating genes (ISGs) in peripheral blood leukocytes (PBL) is significantly increased. However, due to different strains, detection sample types, detection methods, threshold value, etc. the specific effectiveness of early pregnancy diagnosis using ISGs is worth further study. The purpose of this study was to test interferon-stimulated protein 15 (ISG15), 2'–5'-oligoadenylate synthetase 1 (OAS1) and radical S-adenosyl methionine domain containing 2 (RSAD2) for early pregnancy diagnosis in dairy cows. The expression of ISG15, OAS1, and RSAD2 in PBL of pregnant and non-pregnant heifers on days 0, 14, 18, 21 and 28 after artificial insemination (AI) was detected by fluorescence quantitative polymerase chain reaction (PCR). The sensitivity and specificity of the pregnancy diagnosis was analyzed using expression of these three genes separately or in combination by receiver operating characteristic curve. The combination with the highest accuracy used probe primers and duplex fluorescence quantitative PCR. The single quantitative PCR results showed that expression of ISG15, OAS1 and RSAD2 on day 18 after AI was significantly higher in pregnant than in non-pregnant cows. When these three genes were used separately, or in combination, for early pregnancy diagnosis, the sensitivity for the RSAD2 gene was 100%, and the combination of ISG15 with RSAD2 was 94.7%. The duplex quantitative PCR showed that, although the sensitivity of ISG15 alone was 100%, its specificity was only 88.2% (cut-off value 1.402). The sensitivity of RSAD2 alone was 89.5%, and the specificity was 88.2%; however, when the two genes were used in combination, the sensitivity, specificity and diagnostic cut-off value were consistent with the results of single quantitative PCR. These results indicated that a duplex quantitative PCR assay system for early pregnancy diagnosis in cows using ISG15 and RSAD2 was established. Simultaneous detection of expression of ISG15 and RSAD2 by duplex quantitative PCR can effectively improve the diagnostic accuracy for dairy cows.

Vascular and morphological features of the corpus luteum 12 to 20 days after timed artificial insemination in dairy cattle

Our objective was to retrospectively compare pregnant versus nonpregnant cattle in terms of vascular and morphometric changes in corpora lutea between d 12 and 20 following timed artificial insemination (TAI). Crossbred (Gir × Holstein) lactating dairy cows (n = 136) and heifers (n = 111) were bred after synchronizing ovulations using an estradiol plus progesterone (P4)-based protocol. Corpus luteum (CL) characteristics (area, echotexture, blood flow) were recorded at 48-h intervals from d 12 to 20 following TAI using an ultrasound equipped with color Doppler. Blood samples were collected to determine CL function (plasma P4). Pregnancy diagnosis was performed at d 30. Quantitative assessment of colored pixels within the CL was performed using ImageJ software (National Institutes of Health, Bethesda, MD) and echotexture was quantified using custom software. Continuous variables such as luteal tissue area (LTA), CL blood flow (CLBF), adjusted CLBF (ratio LTA:CLBF), mean pixel value (MPV), pixel heterogeneity (HETER), and plasma P4 were analyzed retrospectively as repeated measures (d 12 to 20) in pregnant versus nonpregnant females using PROC MIXED (SAS Institute Inc., Cary, NC). Main effects were pregnancy status, day of cycle, and their interaction. Further analyses used only data from d 16, because this was the earliest time point of deviation between CLBF of pregnant and nonpregnant animals. We created quartiles for each variable and calculated the risk of pregnancy within quartile. Differences were determined using the chi-squared test. Plasma P4 was significantly higher in prospective pregnant versus nonpregnant cattle on d 18 and 20, whereas LTA differed only on d 20. On d 16, CLBF and adjusted CLBF diverged between pregnant and nonpregnant, followed by a progressive reduction in the latter until d 20. Mean pixel value was not affected by pregnancy status, but HETER was lower on d 20 in pregnant than in nonpregnant cattle. Likelihood of pregnancy increased from quartile (Q)1 (lowest values) to Q4 (highest) of CLBF (Q4 vs. Q1, odds ratio = 32.8, 95% confidence interval: 9.6 to 112.1) and adjusted CLBF [Q4 vs. Q1, odds ratio = 25.4, 95% confidence interval: 8.1 to 80.4), whereas a lower risk of pregnancy was observed only for animals within Q1 of plasma P4 [Q4 vs. Q1, odds ratio = 3.1, 95% confidence interval: 1.3 to 7.2). Day 16 quartiles of LTA, MPV, and HETER did not affect odds of pregnancy. In conclusion, we identified distinct CLBF patterns as early as 16 d after TAI and confirmed that CL function is lost by a reduction in blood flow, which precedes physical regression.

Supplementation with long-acting progesterone in early diestrus in beef cattle: I. effect of artificial insemination on onset of luteolysis

Progesterone (P4) supplementation in early diestrus advances changes in the endometrial transcriptome, stimulating embryonic development. However, it also induces early onset of luteolysis. Occurrence of luteolysis before D16 postmating can be detrimental to fertility. A potential counteracting role of the elongating conceptus on early luteolysis is understood poorly. The aim of the study was to evaluate the effect of artificial insemination (AI; ie, pregnancy) on the temporal dynamics of luteolysis of cows supplemented with P4. Nonsuckled beef cows were inseminated at 12 h after estrus (D0: ovulation) or were not inseminated (no-AI). On D3, the AI cows were assigned to receive a single dose of 150 mg of injectable long-acting P4 via intramuscular injection (AI + iP4; n = 23), and the no-AI cows were assigned to receive iP4 (iP4; n = 21) or saline (control, n = 22). Corpus luteum (CL) development and regression were determined by ultrasonography (US) between D3 and D21. Plasma P4 concentrations were measured on D3 and every other day from D9 to D21. Pregnancy status was determined by US (D28‒D32). iP4 supplementation reduced luteal development (D5-D10) compared to the control group and increased incidence of luteolysis between D14 and D15. On D15, the proportion of cows that underwent luteolysis and plasma P4 concentrations differed between the iP4 group (47.6; 2.10 ± 0.47) and the control group (13.6; 4.40 ± 0.46) and was intermediate in the AI + iP4 group, respectively (26.1%; 3.70 ± 0.45 ng/mL; P < 0.05). The AI effects were due to the pregnant cows (n = 7). Considering nonpregnant cows only, the proportion of early luteolysis in the AI + iP4 group (37.5%) was similar to the iP4 group. Pregnancy was not established in cows having a shortened luteal lifespan. Indeed, interval to luteolysis in the AI + iP4 group (15.50 ± 0.66 d) was similar to the iP4 group (16.38 ± 0.46 d), but less than the control group (17.38 ± 0.40 d; P = 0.05). In conclusion, the effect of AI on extending luteal lifespan occurred exclusively in cows that maintained pregnancy.

Investigation of PAG2 mRNA Expression in Water Buffalo Peripheral Blood Mononuclear Cells and Polymorphonuclear Leukocytes from Maternal Blood at the Peri-Implantation Period

: The main objective of this study was to assess PAG2 mRNA expression in maternal blood cells at the peri-implantation period in water buffalo; moreover, we wanted to evaluate the earliest time in which PAG-2 could be detected in maternal blood. Thirty-two lactating buffaloes artificially inseminated (AI) were utilized. Blood was collected at Days 0, 14, 18, 28, 40 after AI (AI = day 0). Pregnancy was diagnosed by ultrasound at Days 28 and 40 post AI. Out of 32 buffaloes, 14 were pregnant (P group) and 18 were not pregnant (NP group). The plasma PAG-2 threshold of 1.0 ng/mL in the P group was reached at day 40 post AI. PAG2 mRNA expression differed between the P and NP groups, and was either evaluated in Peripheral Blood Mononuclear Cells (PBMC) or Polymorphonuclear Leukocytes (PMN), starting from day 14. However, both the estimated marginal means and multiple comparisons showed that PAG2 mRNA expression was higher in PMN than PBMC. In the present study, PAG-2 appeared in the blood (40 Days post AI), and an early expression of PAG2 mRNA at Day 14 post AI was also observed. Although further research is undoubtedly required, PAG2 mRNA in peripheral blood leukocytes could be using to better understand the role that PAGs play during pregnancy in buffalo.

Exacerbated conceptus signaling does not favor establishment of pregnancy in beef cattle

Background

Insufficient production of anti-luteolytic signals by the pre-attachment embryo is considered a major cause of pregnancy failure in cattle. We tested the hypothesis that transfer of multiple blastocysts (n = 5/recipient) and progesterone (P4) supplementation amplify anti-luteolytic signaling and reduce embryonic losses in beef cattle. Cows detected in estrus (D0; n = 104) were assigned randomly to receive 150 mg of injectable long-acting P4 (iP4) or vehicle (non-iP4) on D4 and transcervical transfer of none or five, grade 1, not-frozen, in vitro-produced blastocysts, on D7. Luteal development and time of structural luteolysis were monitored by ultrasonography. Plasma P4 concentrations were determined on D4, D5 and D7, and daily between D14 and D20. Conceptus signaling was monitored by transcript abundance of interferon-stimulated gene 15 (ISG15) in peripheral blood mononuclear cells isolated on D14, D16, D18 and D20. Early embryonic mortality (EEM) was defined as the absence of ISG15 mRNA upregulation over time and/or luteal regression up to D20. Late embryonic mortality (LEM) was defined as the absence of a conceptus with a heartbeat on pregnancy diagnosis at D30 (PD30) after observing upregulation of ISG15 mRNA and extension of luteal lifespan. Pregnant cows presented conceptuses with heartbeat at PD30.

Results

On D5, iP4-treated cows had P4 concentrations 2.07-fold greater than non-iP4 treated (P < 0.001). On D7, P4 concentrations were similar. Pregnant and LEM animals showed a progressive increase in the abundance of ISG15 from D14 to D20. iP4-treated cows detected pregnant at PD30 had 1.53-fold greater abundance of ISG15 mRNA between D14 and D20 than non-iP4 treated cows (P = 0.05). iP4 doubled the frequency of EEM while it did not affect LEM. At PD30, embryonic survival was 37.0% vs. 55.6% for iP4-treated vs. control cows. Majority of pregnant cows (71%) presented only a single viable embryo.

Conclusions

A substantial proportion of cows had EEM (31%) and LEM (20%) even after transferring multiple blastocysts. This argues that mortality was due to poor uterine receptivity that could not be reversed by supplemental P4 or overcome by transferring multiple blastocysts. Further, a given uterine environment was not necessarily adequate to all embryos.

Day-7 embryos generate an anti-inflammatory immune response in peripheral blood immune cells in superovulated cows

PROBLEM

Recently, we demonstrated both in vitro and in vivo that an immunological crosstalk between Day-7 embryo and immune cells exists locally in the uterus in cows. The peripheral immune response to early embryos at Day-7 of pregnancy in cows remains largely unknown. Thus, we aimed to investigate the response of peripheral blood immune cells in the presence of multiple Day-7 embryos in the uterus in donor cows of embryo transfer program.

METHOD OF STUDY

Superovulated cows were either inseminated (n = 13) at 12-18 hours post-estrus or remained without inseminations (n = 6). Blood was collected following insemination (Day-1) and immediately after uterine flushing (Day-7). Polymorphonuclear neutrophils (PMNs) and peripheral blood mononuclear cells (PBMCs) were isolated from whole blood for analysis of gene expression.

RESULTS

Interferon-stimulated genes (ISGs: ISG15 and OAS1) were increased in both PMNs and PBMCs, with up-regulation of PTGES and anti-inflammatory cytokines (TGFB1 and IL10) expressions at Day-7 of post-inseminations in cows, when compared to those at Day-7 in non-inseminated cows.

CONCLUSION

The findings indicate that the presence of multiple embryos in the uterus generates an anti-inflammatory immune response in peripheral blood immune cells at Day-7 of pregnancy in cows, which might help to accept semi-allogenic embryo in the uterus.

Luteal blood flow measured by Doppler ultrasonography during the first three weeks after artificial insemination in pregnant and non-pregnant Bos indicus dairy cows

The objective of this study was to determine if there are differences in luteal size (LS), progesterone (P4), and luteal blood flow (LBF) between pregnant and non-pregnant Bos indicus dairy cows during the first three weeks after insemination, and whether these parameters are related to each other. Lactating cows (n = 13) of mixed parity with a body weight of 430 ± 18 kg (mean ± SD), showing regular estrous cycle were used in the study. All cows were artificially inseminated and were classified as pregnant (embryonic heartbeat on day 30; n = 8) or non-pregnant (inter-estrus interval 17 to 21 days, n = 5). In order to compare the LS and LBF after artificial insemination, B-mode and color Doppler ultrasonography of ovaries were performed on days 4, 5, 6, 7 (first week), 8, 10, 12, 14, (second week), and 16, 17, 18, 19, 20, 21 (third week) in pregnant and non-pregnant cows. Results revealed that the mean LBF was consistently higher (P < 0.05) during days 7 through 21 in pregnant cows than in non-pregnant cows. The mean LS was higher (P < 0.05) on days 6 and 7, and from day 17 onwards, and the mean concentration of P4 was higher (P < 0.05) on days 19, 20, and 21 in pregnant cows. In conclusion, LBF is a more sensitive parameter than LS and P4 for detection of differences in luteal function between pregnant and non-pregnant Bos indicus dairy cows during the first three weeks after AI.

Post-transfer outcomes in cultured bovine embryos supplemented with epidermal growth factor, fibroblast growth factor 2, and insulin-like growth factor 1

This work examined the downstream fetal and placental outcomes of introducing a cocktail of uterine-derived growth factors during bovine embryo culture. Abattoir-derived bovine oocytes were matured and fertilized in vitro. On day 4 post-fertilization, ≥ 8-cell embryos were harvested, pooled and exposed to an embryokine mix, termed EFI, which contained recombinant human epidermal growth factor (10 ng/ml), bovine fibroblast growth factor-2 (10 ng/ml) and human insulin-like growth factor 1 (50 ng/ml) or to a carrier-only control treatment (CON). On day 7, individual, transfer-quality embryos were transferred to recipients. Timed ovulation was completed in mature, non-suckled commercial beef cows. Cows either were artificial inseminated (AI) or received an embryo (ET) on day 7 post-estrus (n = 23-31 cows/treatment over 4 replicate studies). The percentage of grade 1 and 2 morulae and blastocysts was greater (P < 0.05) for EFI-treated embryos than CON. The percentage of pregnant cows diagnosed by transrectal ultrasonography did not differ among the AI and ET groups on days 28, 42 and 56 post-estrus. There also were no differences in the ratio of male to female fetuses determined on day 60 post-estrus by transrectal ultrasonography. On day 21 post-estrus, the relative abundance of three interferon-stimulated gene (ISG) transcripts in peripheral leukocytes were not different based on AI/ET group or the sex of the conceptus. Circulating pregnancy-associated glycoprotein (PAG) concentrations differed (P < 0.05) among days. Also, a difference in PAG concentrations (P < 0.05) were detected between male and female pregnancies in the CON-ET group but not in the AI or EFI-ET groups. Crown-rump length was not affected by AI/ET group on day 42 but were less (P < 0.05) in the CON and EFI-ET groups than the AI group on day 56. These findings implicate EFI supplementation as a means for improving transferable embryo production in a bovine IVP system, but it is not clear if this treatment improves embryo competency after ET.

Perturbations in the uterine luminal fluid composition are detrimental to pregnancy establishment in cattle

Background

A major, unresolved issue is how the uterine microenvironment determines pregnancy success in cattle. Before implantation, conceptus development depends on the uterine secretome (i.e., histotroph). Despite its pivotal role, little is known about the dynamics of histotroph synthesis and changes in composition throughout the early diestrus and the relevance to pregnancy establishment. We hypothesize that disturbances on histotroph composition affect the establishment of pregnancy. Aim was to disturb histotroph composition at early diestrus and verify the effects on: (Exp. 1) timing to restore its composition; and (Exp. 2) pregnancy rate after multiple-embryo transfer. Estrous cycle of multiparous Nelore cows were synchronized and estrus was considered d 0 (D0) of the experiments. Disturbance was through flushing each uterine horn with 30 mL of DMPBS and collecting the resulting uterine luminal flushing (ULF) on D1; D4; D7; D1 + D4 + D7. Control group remained not-collected. In Exp. 1, ULF was collected on D7.5 from all animals and used for quantification of total protein concentration and abundance of albumin. In Exp. 2, three in vitro-produced embryos were transferred to the uterine horn ipsilateral to the ovary containing the CL on D7.5 and pregnancy was checked on D25 by ultrasound.

Results

In Exp. 1, ULF collection on D4 or D7 increased (1.5- to 2.2-folds) the total protein concentration and albumin abundance. ULF collection on D1 did not alter (P > 0.10) these endpoints. In Exp. 2, ULF collected on D4 or D7 decreased pregnancy rates to approximately half of that measured in the remaining groups.

Conclusions

Subtle perturbations imposed to the native intrauterine milieu, such as those caused by a single, low-volume collection of ULF, profoundly disturbs intrauterine composition and pregnancy success. At least 4 d were necessary for the uterus to recover its composition and the functional capacity to carry post-implantation gestation.

Use of Doppler ultrasonography in embryo transfer programs: feasibility and field results

The intensive use of Doppler ultrasonography in several studies in the last decade allowed the characterization of vascular perfusion and the estimation of function of the reproductive organs and tissues along the estrous cycle and pregnancy in cattle. We aim to discuss the possibility of using Doppler imaging and to explore the potential of its inclusion in reproductive programs in cattle industry. Recent studies in dairy and beef cows indicated a high accuracy and sensitivity when Doppler ultrasonography is used to evaluate corpus luteum function and to diagnosis pregnancy between days 20 and 22. Moreover, resynchronization programs starting 5 to 7 days after timed embryo transfer (FTET) coupled with early pregnancy diagnosis were developed for beef cattle, and have been implemented in commercial embryo transfer programs. These strategies allow a reduction in the interval between two FTET from ≈ 40 to 24 days and may improve the gains in reproductive efficiency when compared to traditional programs than begin resynchronization after the pregnancy diagnosis at 30 days. A second alternative to use Doppler imaging is the evaluation of luteal blood perfusion at the time of embryo transfer for selection of recipients with greater receptivity potential. This may increases fertility in FTET, as embryos would not be transferred to females with non-functional CL, and in cases with recipients surplus, females with higher receptivity would be prioritized.

Gene expression of CCL8 and CXCL10 in peripheral blood leukocytes during early pregnancy in cows

Background

The aim of the present study was to evaluate CCL8 and CXCL10 expression and its regulatory mechanism in peripheral blood leukocytes (PBLs) at the time of maternal recognition in cows. Blood samples were collected on 14, 15, 16, 17 and 18 d after artificial insemination (AI). Based on the day of return of estrus, cows were divided into three groups, pregnant (n = 5), early embryonic mortality (EEM; n = 5) and late embryonic mortality (LEM; n = 5). The gene expression levels in PBLs were assessed with quantitative real-time reverse transcription PCR.

Results

The expression of CCL8 and CXCL10 mRNA in PBLs gradually increased from 14 to 18 d of pregnant cows and significant differences were observed on 18 d (P < 0.05), whereas no significant changes were observed both in EEM and LEM cows. Interferon-stimulated protein 15 kDa (ISG15), myxovirus-resistance gene (MX) 1 and MX2 mRNA expression in PBLs increased from 14 to 18 d which was significant on 18 d of pregnant cows as well as in LEM cows (P < 0.05), but no changes were observed in EEM cows. To determine whether the expression of CCL8 and CXCL10 in PBLs was regulated by pregnancy-related substances or not, expression level was assessed after exposure to interferon-τ (IFNT) and CCL16. Monocytes, granulocytes and lymphocytes were obtained using density-gradient centrifugation and flow cytometry. The addition of IFNT (100 ng/mL) and CCL16 (100 ng/mL) to cultured PBLs increased the expression of CCL8 and CXCL10 mRNA (P < 0.05). The expression of ISG15, MX1 and MX2 mRNA in PBLs was also stimulated by IFNT and CCL16 (P < 0.05).

Conclusions

The expression of CCL8 and CXCL10 genes increased in PBLs during early pregnancy. Since IFNT stimulated CCL8 and CXCL10 expression in cultured PBLs, the increase of CCL8 and CXCL10 might be pregnancy-dependent events. The expression of both CCL8 and CXCL10 in PBLs was stimulated by CCL16 as well as IFNT, suggesting a chemokine interaction that at least includes CCL8, CXCL10 and CCL16, and may play a role in regulating maternal recognition in cows.

Oviduct epithelium induces interferon-tau in bovine Day-4 embryos, which generates an anti-inflammatory response in immune cells

Recent studies indicate that communication between the bovine embryo and the mother begins in the oviduct. Here, we aimed to investigate the effect of embryos on bovine oviducts for their immune responses using an in vitro model. First, zygotes were cultured with or without bovine oviduct epithelial cells (BOECs) for 4 days, when embryos had reached the 16-cell stage. At that time, we detected interferon-tau (IFNT) in embryos co-cultured with BOECs, but not in embryos cultured alone. Next, peripheral blood mononuclear cells (PBMCs) were incubated either in media from embryo alone cultures or from co-cultures of embryos with BOECs. The medium from embryo alone cultures did not modulate PBMCs gene expression; whereas the embryo-BOEC co-culture medium increased interferon-stimulated genes (ISGs: ISG15, OAS1, MX2), STAT1, PTGES and TGFB1 but suppressed IL17 expression in PBMCs. Both IFNT-treated BOEC culture medium and IFNT-supplemented fresh medium alone without BOEC, modulated PBMCs gene expressions similar to those by the embryo-BOEC co-culture medium. Further, specific antibody to IFNT neutralized the effect of embryo-BOEC co-culture medium on PBMCs gene expression. Our results indicate that BOECs stimulate embryos to produce IFNT, which then acts on immune cells to promote an anti-inflammatory response in the oviduct.

Transcriptome profiles in peripheral white blood cells at the time of artificial insemination discriminate beef heifers with different fertility potential

Background

Infertility is a longstanding limitation in livestock production with important economic impact for the cattle industry. Female reproductive traits are polygenic and lowly heritable in nature, thus selection for fertility is challenging. Beef cattle operations leverage estrous synchronization in combination with artificial insemination (AI) to breed heifers and benefit from an early and uniform calving season. A couple of weeks following AI, heifers are exposed to bulls for an opportunity to become pregnant by natural breeding (NB), but they may also not become pregnant during this time period. Focusing on beef heifers, in their first breeding season, we hypothesized that: a- at the time of AI, the transcriptome of peripheral white blood cells (PWBC) differs between heifers that become pregnant to AI and heifers that become pregnant late in the breeding season by NB or do not become pregnant during the breeding season; and b- the ratio of transcript abundance between genes in PWBC classifies heifers according to pregnancy by AI, NB, or failure to become pregnant.

Results

We generated RNA-sequencing data from 23 heifers from two locations (A: six AI-pregnant and five NB-pregnant; and B: six AI-pregnant and six non-pregnant). After filtering out lowly expressed genes, we quantified transcript abundance for 12,538 genes. The comparison of gene expression levels between AI-pregnant and NB-pregnant heifers yielded 18 differentially expressed genes (DEGs) (ADAM20, ALDH5A1, ANG, BOLA-DQB, DMBT1, FCER1A, GSTM3, KIR3DL1, LOC107131247, LOC618633, LYZ, MNS1, P2RY12, PPP1R1B, SIGLEC14, TPPP, TTLL1, UGT8, eFDR≤0.02). The comparison of gene expression levels between AI-pregnant and non-pregnant heifers yielded six DEGs (ALAS2, CNKSR3, LOC522763, SAXO2, TAC3, TFF2, eFDR≤0.05). We calculated the ratio of expression levels between all gene pairs and assessed their potential to classify samples according to experimental groups. Considering all samples, relative expression from two gene pairs correctly classified 10 out of 12 AI-pregnant heifers (P = 0.0028) separately from the other 11 heifers (NB-pregnant, or non-pregnant).

Conclusion

The transcriptome profile in PWBC, at the time of AI, is associated with the fertility potential of beef heifers. Transcript levels of specific genes may be further explored as potential classifiers, and thus selection tools, of heifer fertility.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-4505-4) contains supplementary material, which is available to authorized users.

Impact of estradiol cypionate prior to TAI and progesterone supplementation at initial diestrus on ovarian and fertility responses in beef cows

In cattle, early diestrus progesterone (P4) supplementation modulates endometrial function to exert pro- and anti-pregnancy establishment effects; specifically, P4 stimulates conceptus growth, but also induces early onset of luteolysis. This paradoxical effect is frequently related to the inconsistent fertility outcomes that result from P4 supplementation experiments. Aim was to investigate the impact of exogenous estradiol (E2) treatment at the end of timed fixed AI (TAI) on frequency of early luteolysis and pregnancy of beef cows supplemented with P4. Ovulations (D0 of study) of suckled multiparous (n = 643) and primiparous (n = 193) Nelore cows (Bos indicus) were synchronized with an E2/P4-based protocol for TAI and assigned to receive 1.0 mg of estradiol cypionate (CP) or nothing (NoCP) on D-2 and 150 mg of injectable long-acting P4 (iP4) or Placebo (NoiP4) on D4 on a 2 × 2 factorial arrangement. On D15, the iP4 supplementation increased (P < 0.05) the frequency of early luteolysis (NoCP + iP4: 26.0%; [13/50] vs. NoCP: 8.0% [4/50]), but CP prevented this effect (CP + iP4: 8.3% [4/48] and CP: 6.4% [3/47]). The CP improved pregnancy/AI (P/AI) of multiparous (CP: 51.6% [165/320] and NoCP: 35.0% [113/323]; P < 0.001) and primiparous cows (CP: 40.4% [40/99] and NoCP: 24.5% [23/94], P < 0.05), regardless of iP4 treatment. The iP4 supplementation affected P/AI of CP and NoCP treated cows according to follicle size at TAI. For the CP treated cows, the iP4 supplementation improved P/AI of sub-populations of cows with follicles <12.35 mm (42.0% [34/81] vs. 53.1% [34/64]), while for NoCP treated cows, the improvements occurred in subpopulations of cows with follicles ≥12.35 mm (46.1% [35/76] vs. 58.7% [37/63]). In conclusion, strategies associating E2 and P4 supplementation decrease the incidence of early onset of luteolysis and improve P/AI of suckled beef cows with smaller follicles.

Bovine embryo induces an anti-inflammatory response in uterine epithelial cells and immune cells in vitro: possible involvement of interferon tau as an intermediator

Recent observations suggest that the bovine uterus starts to react to the early embryo immediately after its arrival from the oviduct. The present study aimed to investigate the effect of the early developing embryo on the immune-related gene profile in bovine uterine epithelial cells (BUECs) in vitro, and to further examine the impact of conditioned media (CM), either from embryo-BUEC co-culture or embryo culture alone, on gene expression in peripheral blood mononuclear cells (PBMCs). First, BUECs were co-cultured with morulae (n = 10) for D5-D9 (D0 = IVF), and gene expression in BUECs was analyzed. Subsequently, PBMCs were cultured in CM from embryo-BUEC co-culture or D5-D9 embryo culture, and gene expression was evaluated. In BUECs, the embryo induced interferon (IFN)-stimulated genes (ISGs: ISG15, OAS1, and MX2), a key factor for IFN-signaling (STAT1), and type-1 IFN receptors (IFNAR1 and IFNAR2), with suppression of NFkB2, NFkBIA and pro-inflammatory cytokines (TNFA and IL1B). The embryo also stimulated PTGES and PGE2 secretion in BUECs. In PBMCs, both CM from embryo-BUEC co-culture and embryo culture alone induced ISGs, STAT1 and TGFB1, while suppressing TNFA and IL17. Similarly, interferon tau (IFNT) at 100 pg/ml suppressed NFkB2, TNFA and IL1B in BUECs, and also stimulated TGFB1 and suppressed TNFA in PBMCs. Our findings suggest that the bovine embryo, in the first four days in the uterus (D5-D9), starts to induce an anti-inflammatory response in epithelial cells and in immune cells. IFNT is likely to act as one of the intermediators for induction of the anti-inflammatory response in the bovine uterus.

Luteal dynamic and functionality assessment in dairy goats by luteal blood flow, luteal biometry, and hormonal assay

This study aimed to assess the luteal dynamics of pregnant and non-pregnant Saanen goats throughout an estrous cycle by B-mode and color Doppler ultrasonography (US) associated with a P4 hormonal assay. Furthermore, a cutoff point was chosen to determine the corpus luteum (CL) functionality by luteal biometry (LB) measurement and luteal blood flow (LBF) assessment. Ultrasound assessment was carried out daily throughout an entire estrous cycle (21 days) in 23 Saanen goats pre-synchronized and inseminated in the breeding season. The plasmatic P4 concentration was determined daily by radioimmunoassay. LB parameters (diameter, area, and volume) were measured using the maximum area of a cross-section of the CL. LBF assessment was performed subjectively by percentage of area of colored pixels and objectively by calculating the number of the colored pixels. Eventually, 45.0% (9/20) and 55.0% (11/20) of goats became pregnant and or remained non-pregnant, respectively. The LB and LBF demonstrated value stabilization on the 9th day of the estrous cycle and maximum values on the 12th and 13th days of the estrous cycle, respectively. LB presented a progressive decrease in the luteal regression phase, whereas the LBF decreased abruptly in association with P4. The LBF values were more reliable in predicting the luteal functionality when compared to the LB data. The number of colored pixels accurately predicted values of P4 >1.0 ng/mL, reaching only 17% of the maximum values, and 1200 colored pixels as a minimum cutoff point when compared to the use of 53% of the maximum values and a minimum luteal diameter of 9.0 mm as cutoff point for P4 >1.0 ng/mL. The LBF assessment was more informative about the CL functionality throughout the complete luteal phase when compared to the LB. The use of the number of colored pixels is indicated for research regarding luteal functionality due to their greater correlation with P4 values. In addition, the luteal subjective evaluation can be used under field conditions due to greater convenience and similar pattern of correlation with P4.

Peri-ovulatory endocrine regulation of the prostanoid pathways in the bovine uterus at early dioestrus

We hypothesised that different endocrine profiles associated with pre-ovulatory follicle (POF) size would impact on uterine prostanoid pathways and thereby modulate the histotroph composition. Beef cows (n = 15 per group) were hormonally manipulated to have small (SF-SCL group) or large (LF-LCL group) pre-ovulatory follicles (POF) and corpora lutea (CL). Seven days after induction of ovulation, animals were slaughtered and uterine tissues and flushings were collected for quantification of prostanoids. The POF and CL size and the circulating progesterone concentrations at Day 7 were greater (P < 0.05) in the LF-LCL cows than in the SF-SCL group, as expected. The abundance of 5 out of 19 genes involved in prostanoid regulation was different between groups. Transcript abundance of prostaglandin F2α, E2 and I2 synthases was upregulated (P < 0.05) and phospholipase A2 was downregulated (P < 0.05) in endometrium of the LF-LCL group. No difference (P > 0.1) in prostanoid concentrations in the endometrium or in uterine flushings was detected between groups. However, prostaglandin F2α and E2 concentrations in the uterine flushings were positively correlated with the abundance of transcripts for prostaglandin endoperoxide synthase 2 (0.779 and 0.865, respectively; P < 0.002). We conclude that endometrial gene expression related to prostanoid synthesis is modulated by the peri-ovulatory endocrine profile associated with POF size, but at early dioestrus differences in transcript abundance were not reflected in changes in prostanoid concentrations in the uterine tissue and fluid.

Identification of serum protein markers for early diagnosis of pregnancy in buffalo

Improper or delayed pregnancy diagnosis has significant impact over animal production, particularly in buffaloes which inherently suffer from several reproductive inefficiencies. Thus the present study has undertaken to identify serum protein markers pertaining to early pregnancy diagnosis in buffaloes. Serum samples were collected from 10 pregnant Murrah Buffalo heifers at weekly intervals from days 0-35 post-artificial insemination and from 12 inseminated non-pregnant cyclic buffalo heifers on days 0, 7, 14 and 21. Two-dimensional gel electrophoresis and densitometric analysis revealed the presence of five protein spots showing average density fold change of ≥4 during early pregnancy. Mass spectrometry analysis identified these up-regulated proteins as anti-testosterone antibody light chain, apolipoprotein A-II precursor, serum amyloid A, cytokeratin type II, component IV isoform 1, which are have established roles in embryogenesis, but over-expression of the fifth identified protein immunoglobulin lambda light chain in pregnancy has been elucidated as a novel finding in the current study. Further, with bioinformatics analysis, potential antigenic B-cell epitopes were predicted for all these five proteins. An antibody cocktail-based approach involving antibodies against all these five up-regulated entire proteins or their epitopes could be developed for early detection of pregnancy in buffaloes. © 2016 Japanese Society of Animal Science.

Interferon stimulated genes as peripheral diagnostic markers of early pregnancy in sheep: a critical assessment

We investigated the diagnostic reliability of pregnancy detection using changes in interferon stimulated gene (ISG) messenger RNA (mRNA) levels in circulating immune cells in ewes. Two different groups of ewes (an experimental group, experiment 1 and a farm group, experiment 2) were oestrus-synchronized and blood sampled on day 14 (D0=day of insemination in control animals, experiment 1) and day 15 (experiment 2). Real-time PCR were performed to evaluate the abundance of different ISG mRNAs. In the experimental group, peripheral blood mononuclear cells of 29 ewes born and bred in experimental facilities were isolated using a Percoll gradient method. Gene expression for Chemokine (C-X-C motif) ligand 10 (CXCL10), Myxovirus (influenza virus) resistance 1 (MX1) and Signal transducer and activator of transcription 1 (STAT1) mRNA were, respectively, 8.3-fold, 6.1-fold and 2.7-fold higher (P0.10) in CXCL10, STAT1, MX1, Myxovirus (influenza virus) resistance 2 (MX2) and ISG15 ubiquitin-like modifier (ISG15) mRNA expression were found between pregnant and non-pregnant ewes. The ROC curves and the hierarchical classification generated from the real-time PCR data failed to discriminate between pregnant and non-pregnant animals. In this group of animals, our results show a strong variability in ISG expression patterns: 17% of animals identified as non-pregnant by the five tests were in fact pregnant, only 52% of pregnant animals had at least two positive results (two genes above threshold), whereas up to five positive results (five genes above threshold) were needed to avoid misclassification. In conclusion, this study illustrates the high variability in ISG expression levels in immune circulating cells during early pregnancy and, therefore, highlights the limits of using ISG expression levels in blood samples, collected on PAXgene® tubes on farms, for early pregnancy detection in sheep.

Improved fertility in suckled beef cows ovulating large follicles or supplemented with long-acting progesterone after timed-AI

We aimed to evaluate the effects and the interaction of size of the preovulatory follicle (POF) and long-acting progesterone (P4) supplementation after timed-AI on CL function and pregnancy success in beef cows. In experiment 1, ovulations of beef cows were synchronized starting on Day -10, and cows were split to receive sodium cloprostenol (large follicle group; LF; n = 31) or nothing (small follicle group; SF; n = 35). Ovulations were induced on Day 0, and cows were inseminated. Ovulated cows were assigned to receive placebo (LF/control group, n = 14; and SF/control group, n = 9) or 150 mg of long-acting P4 on Day 4.5 (LF/P4 group, n = 13; and SF/P4 group, n = 12). Diameter of POF, blood flow in POF wall, ovulation rate, and size and vascularization of CL were greater (P < 0.05) in LF group. In experiments 2 (unknown cyclic status) and 4 (noncycling), ovulations were synchronized, and beef cows received placebo or 150 mg of long-acting P4 on Day 4 after timed-artificial insemination. In experiment 2, pregnancy/AI (P/AI) did not differ (P > 0.1) between P4-treated (53.2%; 209/393) and control cows (56.2%; 219/390), but P/AI was greater in cows with a CL < 0.9 cm(2) on Day 4 that were P4-treated (57.9%, 22/38) versus placebo-treated (40.4%, 21/52; P < 0.05). In Experiment 4, P/AI was greater (P < 0.05) in P4-treated cows (55.6%, 105/189 vs. 46.0%, 86/187). In Experiment 3, cyclic-suckled beef cows were treated as described in Experiment 1 to generate animals with small (SF; n = 111) or large POF (LF; n = 109), and subdivided to receive placebo or P4 on Day 4. POF size, ovulation rate, CL area, and P/AI were greater (P < 0.007) in the LF group. Pregnancy/AI in ovulated cows were lower (P = 0.05) in the SF/control group (41.5%, 17/41) compared to LF/control group (62%, 31/50) and were similar for the SF/P4 group (55.6%, 25/45) and LF/P4 group (57%, 28/49) compared to others. In summary, smaller and less vascularized POF results in less functional CL and reduces ovulatory rate and P/AI in cyclic beef cows; the long-acting P4 injection on Day 4 after timed-artificial insemination may attenuate the negative effects of small POF/CL; and postovulatory P4 supplementation improved fertility in anestrous beef cattle.

Predicting Embryo Presence and Viability

Pregnancy establishment, followed by birth of live offspring, is essential to all mammals. The biological processes leading up to pregnancy establishment, maintenance, and birth are complex and dependent on the coordinated timing of a series of events at the molecular, cellular, and physiological level. The ability to ovulate a competent oocyte, which is capable of undergoing fertilization, is only the initial step in achieving a successful pregnancy. Once fertilization has occurred and early embryonic development is initiated, early pregnancy detection is critical to provide proper prenatal care (humans) or appropriate management (domestic livestock). However, the simple presence of an embryo, early in gestation, does not guarantee the birth of a live offspring. Pregnancy loss (embryonic mortality, spontaneous abortions, etc.) has been well documented in all mammals, especially in humans and domestic livestock species, and is a major cause of reproductive loss. It has been estimated that only about 25-30% of all fertilized oocytes in humans result in birth of a live offspring; however, identifying the embryos that will not survive to parturition has not been an easy task. Therefore, investigators have focused the identification of products in maternal circulation that permit the detection of an embryo and assessment of its well-being. This review will focus on the advances in predicting embryonic presence and viability, in vivo.