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Prior to implantation in cattle, the mucous medium contained in the uterine lumen serves as a working interface for molecular exchange and signaling between the lining endometrium and the embryo. The composition of this luminal fluid changes temporally according to the secretory and reabsorptive activities of the uterus and the embryo, which are under complex regulation. Via this interface, both the embryo and the endometrium reprogram each other's functions to support pregnancy continuation beyond the pre-implantation period. More specifically, the embryo receives elongation signals and the uterus receives anti-luteolytic stimuli. Here, characteristics of the luminal compartment as well as the regulation of its composition to determine the pregnancy outcome will be discussed.

In vivo- and in vitro-produced bovine embryos have different metabolic profiles and differences in gene transcription patterns. These embryos also have a distinct ability to establish and sustain early pregnancies. Small extracellular vesicles (sEVs) are secreted by embryos and carry bioactive molecules, such as miRNAs. We hypothesize that in vivo or in vitro-produced bovine hatched blastocysts on Day 9 and the sEVs secreted by them have different miRNA profiles. To address this hypothesis, embryos of both groups were placed in in vitro culture on Day 7. After 48 h, hatched embryos and hatched embryo-conditioned media (eCM) of both groups were collected. A total of 210 miRNAs were detected in embryos of both groups, of these 6 miRNAs were downregulated, while 7 miRNAs were upregulated in vitro group when compared to in vivo group. sEVs were isolated from eCM to determine miRNA profile. A total of 106 miRNAs were detected in both groups, including 14 miRNAs upregulated in sEVs from in vivo-eCM, and 2 miRNAs upregulated in sEVs from in vitro-eCM. These miRNAs express in embryos and sEVs secreted by them regulate early embryonic developmental and endometrial pathways, which can modify embryo-maternal communication during early pregnancy and consequently affect pregnancy establishment.

Made available in DSpace on 2022-04-29T08:46:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-11-15 In cattle, uterine luminal fluid (ULF) is the main source of molecules that support embryo development and survival during the peri-implantation period. Our overarching hypothesis is that peri-estrus changes in uterine function, including ULF accumulation and absorption, are uneven among individuals, and affect ULF composition and fertility. Our objectives were (1) to characterize temporal and spatial changes in ULF volume, endometrial and luteal blood perfusion, endometrial and luteal size, and circulating progesterone concentrations during the peri-estrus period in beef heifers and (2) to associate such changes with the metabolite composition in the ULF, 4 days after estrus (d 0). Fourteen Bos indicus heifer that presented a PGF2α responsive CL received 500 μg PGF2α analog i.m. and were examined daily by rectal B-mode and pulse-wave color-Doppler ultrasonography until the fifth day after estrus (d 5). The composition of the ULF was analyzed by targeted mass spectrometry on d 4. Multivariate analyses clustered heifers according to ovarian, uterine, and hormonal variables in clusters A (n = 5) and B (n = 8 heifers). Concentrations of Pro, Ala, Leu, Gly, Val, Lys, Ile, Phe, Asp, Orn, Tyr, Arg, Trp, Suc, Cit, ADMA, the sum of essential Amino Acids (AA), sum of nonessential AA, sum of aromatic AA, and total AA were greater in cluster A (FDR ≤ 0.05). ULF volume dynamics and uterine, ovarian, and hormonal variables during the peri-estrus period presented a concerted variation among heifers within clusters, which was associated with the ULF composition 4 days after estrus. Department of Animal Sciences University of Florida FL Department of Animal Reproduction School of Veterinary Medicine and Animal Sciences University of São Paulo Department of Surgery Division of Urology Federal University of São Paulo School of Veterinary Medicine São Paulo State University School of Veterinary Medicine São Paulo State University

Development of new methods for early diagnosis of pregnancy can be important to increase the reproductive efficiency and profitability of dairy herds. The bovine conceptus secretes IFN-τ that stimulates the transcription of several genes in circulating immune cells and extrauterine tissues. The aims of this study were to evaluate the mRNA abundance for pregnancy predictability of a classic gene stimulated by IFN-τ (ISG15) and a novel potential pregnancy marker (LGALS3BP) in peripheral blood mononuclear cells (PBMC), total blood leukocytes (TBL) or milk leukocytes (TML), and cervical cells (CC) on d 20 after timed artificial insemination (TAI) in dairy cattle. Eighteen Holstein females (12 cows and 6 heifers) were submitted to an estrous synchronization protocol for TAI (d 0). On d 20 post-TAI, blood samples were collected from coccygeal vessels for isolation of PBMC and in Tempus Blood RNA tubes (Applied Biosystems) for TBL. Samples of CC were collected using a cytological brush, and the TML were isolated from milk samples collected before routine milking. Pregnancy diagnosis was performed on d 30 post-TAI using transrectal ultrasonography, and females were classified as pregnant (n = 8) or nonpregnant (n = 10). Total RNA was extracted and mRNA abundance of target genes (ISG15 and LGALS3BP) was quantified by reverse-transcription quantitative PCR and normalized in relation to reference genes. Data were analyzed by ANOVA using the MIXED procedure of SAS (SAS Institute Inc.). The mRNA abundance of ISG15 was greater in pregnant than in nonpregnant animals for PBMC, TBL, and CC. No difference was detected for TML based on pregnancy status. For LGALS3BP mRNA abundance, no difference was detected between pregnant and nonpregnant animals for PBMC, TBL, and TML, but a tendency for greater abundance in pregnant animals was observed for CC. The fold change for ISG15 in each pregnant cow related to the mean of nonpregnant animals was 2.73 ± 0.31, 3.40 ± 2.17, 1.64 ± 0.29, and 0.005 ± 0.002 for PBMC, CC, TBL, and TML, respectively. The fold change for LGALS3BP in each pregnant cow related to the mean of nonpregnant animals was 0.97 ± 0.38, 1.77 ± 0.39, 0.20 ± 0.08, and 0.70 ± 0.11 for PBMC, CC, TBL, and TML, respectively. The receiver operating characteristic curve analysis indicated that ISG15 abundance predicted pregnancy in PBMC (area under curve, AUC = 0.92) and CC (AUC = 0.77) but not in TBL (AUC = 0.72) or TML (AUC = 0.52). In conclusion, mRNA abundance for ISG15 in PBMC was the best predictor for pregnancy at d 20 post-TAI, whereas TBL and TML were not good predictors of pregnancy on d 20 post-TAI. The mRNA abundance of LGALS3BP was not associated with pregnancy status in any type of cell evaluated.

This study aimed to evaluate the effect of seminal plasma on bovine sperm cryopreservation and to assess the integrity of plasma and acrosomal membranes, mitochondrial potential, remodelling of F-actin cytoskeleton and sperm chromatin fragmentation during the cooling, equilibrium and freezing/thawing stages. Six ejaculates collected from seven Nelore bulls (n = 42) were used in this study. Each ejaculate was divided into two aliquots (with seminal plasma = SP group; without seminal plasma = NSP group) and packed to a final concentration of 50 × 106 sperm per straw. Statistical analyses were performed using SAS software (version 9.3), and p ≤ .05 was considered significant. A time effect was observed for all sperm characteristics (p .05). The presence of seminal plasma better preserved the acrosomal integrity (SP = 75.2% and NSP = 71.7%; p < .05) and also provided lower F-actin remodelling during cryopreservation process (SP = 29.9% and NSP = 32.4%; p < .05). Regarding to the cryopreservation stages, it was observed that cooling step induced higher remodelling of F-actin than the equilibrium and freezing/thawing stages (56.3%, 32.2% and 23.9%, respectively; p < .05). The equilibrium step had minor influence on overall sperm characteristics while the freezing/thawing stage was responsible for the highest percentage of damage in plasma membrane (-65.2%), acrosomal membrane (-34.0%) and mitochondrial potential (-48.1%). On the other hand, none of the cryopreservation stages affected chromatin integrity. It was concluded that the presence of seminal plasma provides increased acrosomal integrity and reduced remodelling of F-actin cytoskeleton. Higher F-actin remodelling is observed after the cooling step while the freezing/thawing step is most damaging to sperm membranes and mitochondrial potential during bovine sperm cryopreservation.

The objective of this study was to create a stochastic, agent-based simulation model of a synthetic population of beef cattle, and then use it to compare the technical performance of different reproductive strategies. The model was parameterized using data from a real beef cattle herd and from the peer-reviewed scientific literature to represent a Nelore cattle herd in the state of Sao Paulo, Brazil. Ten scenarios were evaluated: natural mating (NM) only (ONM); one timed artificial insemination (TAI) plus NM (1TAI + NM); two TAI plus NM, with 24, 32, and 40 days between inseminations (2TAI/24 + NM, 2TAI/32 + NM, and 2TAI/40 + NM, respectively); three TAI without NM, with 24, 32, and 40 days between TAI (3TAI/24, 3TAI/32, and 3TAI/40, respectively); and three TAI plus NM, with 24 and 32 days (3TAI/24 + NM and 3TAI/32 + NM, respectively). NM began 10 days after the last TAI and was performed until the end of the breeding season. The size of the female herd was set to contain up to 400 individuals. The bull population was established at 0, 7, or 15 bulls depending on the used scenario. Simulation was performed for 5000 days. The outcomes for each scenario are means ± S.E. assessed on 32 farms at 1-day time intervals and on an animal-by-animal basis after steady state was reached (1825 days). The 3TAI/24 + NM scenario resulted in a greater number of births (279.85 ± 0.47 births), while the ONM scenario had the least value (202.38 ± 0.43 births). The heaviest males and females at weaning belonged to 3TAI/24, with 190.85 ± 0.17 kg for males and 173.89 ± 0.13 kg for females. The ONM scenario had the lightest males (166.84 ± 0.18 kg) and females (151.75 ± 0.16 kg). The greatest and least total pregnancy rates were found in 3TAI/24 + NM (0.91 ± 0.00) and ONM (0.62 ± 0.00), respectively. The ONM scenario required 52.5 days more than scenarios that included TAI to reach 50% of pregnancy. The greatest ages at culling for cows was 3TAI/24 + NM (3658.88 ± 10.41 days). In contrast, the lowest age at culling was found in ONM (2823.93 ± 8.28 days). We concluded that the proposed model represents the main interactions of a real beef cattle herd. It has all the advantages of a physical experiment, but does not require incurring significant expenses nor altering the real system. This study offers evidence that the scenarios that present the best technical performance are those that used TAI with a 24-day interval between inseminations.

Clinical endometritis (CE) and subclinical endometritis (SE) are one of the main uterine diseases in dairy cows during the puerperium period, which can directly affect milk production and fertility in dairy herds. The aim of this study was to investigate the effects of the CE and SE on the subsequent reproductive performance and milk production of dairy cows in Brazilian herds. A total of 279 lactating Holstein dairy cows (28 to 33 d in milk) from six commercial farms were evaluated. The cows were classified into three groups: healthy cows (without CE and SE, n = 161), cows with CE (vaginal discharge score = 3 and ≥ 18% PMNL, n = 83) and cows with SE (absence of signs of CE and > 18% PMNL, n = 35). Cows with CE and SE had a lower (P P

Immune cells play a central role in early pregnancy establishment in cattle. We aimed to: (1) discover novel early-pregnancy-induced genes in peripheral blood mononuclear cells (PBMC); and (2) characterize the temporal pattern of early-pregnancy-induced transcription of select genes in PBMC and peripheral blood polymorphonuclear cells (PMN). Beef heifers were artificially inseminated on D0 and pregnancies were diagnosed on D28. On D10, 14, 16, 18, and 20, blood was collected for isolation of PBMC and PMN from heifers that were retrospectively classified as pregnant (P) or non-pregnant (NP). PBMC samples from D18 were submitted to RNAseq and 220 genes were differentially expressed between pregnant (P) and non-pregnant (NP) heifers. The temporal abundance of 20 transcripts was compared between P and NP, both in PBMC and PMN. In PBMC, pregnancy stimulated transcription of IFI6, RSAD2, IFI44, IFITM2, CLEC3B, OAS2, TNFSF13B, DMKN and LGALS3BP as early as D18. Expression of IFI44, RSAD2, OAS2, LGALS3BP, IFI6 and C1R in PMN was stimulated in the P group from D18. The novel early-pregnancy induced genes discovered in beef heifers will allow both the understanding of the role of immune cells during the pre-attachment period and the development of technologies to detect early pregnancies in beef cattle.

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.

Made available in DSpace on 2020-12-12T02:26:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação para o Desenvolvimento da UNESP (FUNDUNESP) Universidade Estadual Paulista The aim of this research was to evaluate the effect of recombinant bovine somatotropin (bST) on pregnancy per artificial insemination (P/AI), cellular composition of the corpus luteum (CL) and endometrial gland morphometry. In Experiment 1, Nelore cows (n = 587) received a fixed-time artificial insemination (FTAI) protocol and, at insemination, received 0, 250 or 500 mg of bST subcutaneously (SC). In Experiment 2, Nelore cows (n = 243) received 0 or 500 mg of bST, SC, on D7 (D0 = day of FTAI). Blood samples were collected on D7 and D16 to measure progesterone (P4) concentrations. In Experiments 1 and 2, pregnancy diagnosis was performed 30 days after FTAI. In Experiment 3, Nelore heifers (n = 20) received a FTAI protocol, but were not inseminated, and on D0 (ovulation day), they received 0 (bST 0; n = 9) or 500 mg of bST (bST 500; n = 11), SC. The heifers were slaughtered on D15 (D0 = ovulation day), at which time the CL was evaluated for diameter, weight, a percentage of large (LLC) and small (SLC) luteal cells, and the concentration of progesterone in plasma measured. The number, perimeter and area of superficial and deep endometrial glands were evaluated. There was no difference in P/AI when bST was applied on D0 and D7. In Experiment 1, P/AI did not differ among treatments, with 59.28% (115/194), 58.38% (115/197) and 65.82% (129/196) for the bST 0, 250 and 500 treatments, respectively. In Experiment 2, P/AI did not differ between treatments, with 57.3% (71/124) and 60.5% (62/119) for the bST 0 and 500 treatments, respectively. Plasma progesterone concentrations on D16 was greater in the bST 500 (11.63 ± 0.84 ng/mL) than bST 0 (9.83 ± 0.88 ng/mL). In Experiment 3, there was no difference in ovarian diameter and weight, CL diameter, percentage of SLC, P4 concentrations and endometrial gland morphology. Heifers in the bST 500 treatment had heavier CL (3.11 ± 0.32 vs. 2.25 ± 0.20 g); however, the bST 0 treatment heifers had a greater percentage of LLC than did the bST 500 treatment (13.72 ± 1.16% vs. 8.60 ± 1.52). It was concluded that the doses of bST used in this study do not increase P/AI; however, they do cause changes in P4 concentration and the cellular composition of the CL. São Paulo State University - UNESP University of Florida North Florida Research & Education Center Institute of Food and Agricultural Sciences University of São Paulo RG Advanced Genetics University of São Paulo West São Paulo State University - UNESP

Made available in DSpace on 2022-04-28T19:43:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-01-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) In cattle, 17β-estradiol (E2) stimulates prostaglandin F2α (PGF2α) synthesis, which causes luteolysis. Except for the well-established upregulation of oxytocin receptor gene (OXTR), molecular mechanisms of E2-induced PGF2α release in vivo remain unknown. We hypothesized that E2-induced PGF2α release requires de novo transcription of components of the PGF2α synthesis machinery. Beef cows (n = 52) were assigned to remain untreated (Control; n = 10), to receive 50% ethanol infusion intravenously (Placebo; n = 21), or 3 mg E2 in 50% ethanol infusion intravenously (Estradiol; n = 21) on day 15 (D15) after estrus. We collected a single endometrial biopsy per animal at the time of the treatment (0h; Control B0h group), 4 hours (4h; Placebo B4h group and Estradiol B4h group), or 7 hours (7h; Placebo B7h group and Estradiol B7h group) post-treatment. Compared to the Placebo group, the Estradiol group presented significantly greater 13,14-dihydro-15-keto-PGF2α concentrations between 4h and 7h and underwent earlier luteolysis. At 4h, the qPCR analysis showed a lower abundance of ESR1, ESR2 and aldo-keto reductase family 1 member B1 (AKR1B1) genes in the Estradiol B4h group, and a greater abundance of OXTR compared to the Placebo B4h group. Similarly, the E2 treatment significantly reduced the abundance of AKR1B1, and AKR1C4 in the Estradiol B7h group, compared to the placebo group. Overall, E2-induced PGF2α release and luteolysis involved an unexpected and transient downregulation of components of the PGF2α-synthesis cascade, except for OXTR, which was upregulated. Collectively, our data suggest that E2 connects newly-synthesized OXTR to pre-existing cellular machinery to synthesize PGF2α and cause luteal regression. Agrarian Sciences Center State University of Maranhão Tocantine Region Department of Animal Reproduction University of São Paulo North Florida Research and Education Center Institute of Food and Agricultural Sciences University of Florida Department of Animal Sciences University of Florida Department of Pharmacology and Biotechnology São Paulo State University Department of Animal Science Luiz de Queiroz College of Agriculture University of São Paulo Department of Animal Sciences São Paulo State University Department of Pharmacology and Biotechnology São Paulo State University Department of Animal Sciences São Paulo State University FAPESP: 2015/03331-3)

The objective of this study was to compare the efficiency of estradiol benzoate (EB) and 17β-estradiol (E2) associated with progesterone (P4) in a fixed-time artificial insemination (FTAI) protocol. We hypothesized that E2+P4 induces an earlier emergence of a new follicular wave (NFW), improving pre-ovulatory follicle diameter and pregnancy rates to FTAI (P/FTAI). In Exp.1, on Day 0 (D0), all Bos indicus cows (n = 12/group) received an intravaginal P4 device and a dose of PGF2α analogue. On D0, females were randomly assigned to receive EB or E2+P4. On D8.5, P4 intravaginal devices were removed and a dose of PGF2α and EB were administered in all females followed by fixed-timed AI on D10. Between D0 and D10, the dominant follicular growth was determined by ovary ultrasonography exams. On D8.5 and D10 the percentage of color power-Doppler signals in the dominant follicular wall was evaluated. In Exp. 2, 467 females (2-year-old nulliparous [n = 76], primiparous [n = 92] and pluriparous [n = 299]) were subjected to the similar FTAI and assigned to be treated with EB (n = 243) or E2+P4 (n = 224). Pregnancy diagnosis was performed 30 days after FTAI by ultrasonography. The day to emergence of NFW was similar between treatments (EB: 3.7 ± 0.37 vs. E2+P4: 3.3 ± 0.3, P = 0.76). Females treated with E2+P4 presented greater (P = 0.06) follicular growth between the emergence and D9 (1.18 ± 0.07) than those treated with EB (0.97 ± 0.08). There was also a positive effect (P 0.05) of E2+P4 on diameter of the dominant follicle on D9 (13.0 ± 0.6 vs. 10.9 ± 0.55) and blood perfusion of the follicle wall on D8.5 (49 vs. 40%). There was a treatment by parity category interaction effect on P/FTAI (P 0.05). Treatment with E2+P4 was advantageous to P/FTAI of primiparous cows (E2+P4: 58% and EB: 30%). However, for nulliparous and pluriparous cows, P/FTAI was similar between treatments (∼50%). In conclusion, in a E2/P4-based protocol for FTAI, E2+P4 is as efficient as EB in inducing new follicular emergence within a similar day range, but it results similar or greater P/FTAI.

In a companion paper, Ojeda-Rojas et al. (2021) [1] describe a stochastic agent-based simulation (ABS) model of a cow-calf operation on a commercial farm in São Paulo, Brazil. The model's parameterization was based on data collected from two sources: a real beef cattle herd and related scientific literature. Based on the mentioned simulation model, this study aims to assess the economic outcome of 10 different reproductive scenarios: Natural mating only (ONM); one timed artificial insemination (TAI) plus natural mating (NM) (1TAI + NM); two TAI plus NM, with 24, 32, and 40 days between TAI (2TAI/24 + NM, 2TAI/32 + NM, and 2TAI/40 + NM, respectively); three TAI without NM, with 24, 32, and 40 days between TAI (3TAI/24, 3TAI/32, and 3TAI/40, respectively); and three TAI plus NM, with an interval between TAI of 24 (3TAI/24 + NM) and 32 days (3TAI/32 + NM). The simulation was performed on an animal-by-animal basis over a time horizon of 5000 days. Each scenario had 32 farms, and each farm kept up to 400 adult females. According to the scenario, a bull population was composed of 0, 7, or 15 individuals. The outcomes, represented as means ± standard deviations, were assessed after reaching a steady-state (1825 days). The model outcomes showed that the 3TAI/24 + NM scenario resulted in higher incomes (US$ 96,479.19 ± 709.81), whereas the ONM scenario had the lowest incomes (US$ 79,753.37 ± 741.87). The 3TAI/24 + NM (US$ 101.720.63 ± 79.21) and ONM (US$ 90.898.58 ± 59.17) scenarios presented the highest and lowest total operating costs (TOC), respectively. However, when TOC was evaluated per kg of the weaned calf, the highest and lowest costs were associated with the ONM (US$ 2.81 ± 0.03/kg) and 2TAI/24 + NM (US$ 2.17 ± 0,04/kg) scenarios, respectively. Our model suggests that reproductive strategies that use TAI have a better economic performance than those under NM. However, when performing three TAI with an interval of 40 days, the benefit was lower; in some cases, it was even worse than the ONM. Combining TAI with early pregnancy diagnosis resulted in better economic performance than other TAI programs and NM. The 2TAI/24 + NM scenario outperformed the others due to the contrast between its high income and moderate costs. Beef cattle production is a highly complex system. Simulations models, specifically ABS models, could make the decision-making process on complex systems straightforward and effective. Furthermore, ABS models can overcome the limitations of conventional research approaches, such as high costs and long experimentation periods.

Maternal nutrition during pregnancy influences postnatal life of animals; nevertheless, few studies have investigated its effects on the productive performance and reproductive development of heifers. This study evaluated the performance, reproductive development, and correlation between reproduction × fat thickness and performance × ribeye area (REA) traits of heifers. We also performed an exploratory genomic association during the rearing period in heifers submitted to fetal programming. The study comprised 55 Nellore heifers born to dams exposed to one of the following nutritional planes: control, without protein-energy supplementation; PELT, protein-energy last trimester, protein-energy supplementation offered in the final third of pregnancy; and PEWG, protein-energy whole gestation, protein-energy supplementation upon pregnancy confirmation. Protein-energy supplementation occurred at the level of 0.3% live weight. After weaning, heifers were submitted to periodic evaluations of weight and body composition by ultrasonography. From 12 to 18 months, we evaluated the reproductive tract of heifers to monitor its development for sexual precocity and ovarian follicle population. The treatments had no effect (p > 0.05) on average daily gain; however, the weight of the animals showed a significant difference over time (p = 0.017). No differences were found between treatments for REA, backfat, and rump fat thickness, nor for puberty age, antral follicular count, and other traits related to reproductive tract development (p > 0.05). The correlation analysis between performance traits and REA showed high correlations (r > 0.37) between REA at weaning and year versus weight from weaning until yearling; however, no correlation was found for reproductive development traits versus fat thickness (p > 0.05). The exploratory genomic association study showed one single-nucleotide polymorphism (SNP) for each treatment on an intergenic region for control and PEWG, and the one for PELT on an intronic region of RAPGEF1 gene. Maternal nutrition affected only the weight of the animals throughout the rearing period.

Different approaches have been used to improve conception rates at foal heat. Omega-3 fatty acids family and derivatives have improved reproductive efficiency in ruminants, but literature lacks studies evaluating these components on equines. The objective of this study was to evaluate effects of mare dietary supplementation with microalgae rich in docosahexaenoic acid (DHA) during peripartum on follicular dynamics and uterine involution in early post-partum. Eighteen pregnant mares, no particular breed, 410 ± 39.5 kg body weight (BW), and 7.83 ± 2.01 yr old were used. Mares were randomly assigned to control (CONT) or supplementation with microalgae rich in DHA at 0.06 g/kg BW (ALG). Treatments were supplied from 90 d prior to expected foaling date until 7 d after first ovulation. Reproductive evaluations were performed during early post-partum until 7 d after first ovulation through rectal palpation and ultrasonography of the following parameters: uterine and endometrium diameters, intrauterine fluid (IUF), uterine echogenicity, uterus tone, and follicular dynamics. Endometrial cells samples were collected to assess mRNA expression of CRP, IL-1β and AKR1C4, using RT-qPCR. Data were analyzed by mixed procedure of SAS. ALG mares had smaller uterine horns diameters and greater uterine echogenicity during post-partum in comparison with CONT. No treatment effects were detected for other characteristics evaluated, but a day effect was observed for uterine and endometrium diameter, IUF, uterine echogenicity, and transcript abundance of endometrial AKR1C4. Supplementation with DHA during peripartum may benefit uterine involution process and odds of early conception, but more studies should be performed regarding fertility.

Made available in DSpace on 2021-06-25T15:06:26Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-06-01 Zoetis Animal Health Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Follicular dynamics and pregnancy per AI (P/AI) of cattle submitted to resynchronization 13 d after TAI using a progesterone (P-4) insert and supplementary injectable progesterone (iP(4)) were determined. There was synchronization of ovulation timing imposed (Day 0 = expected estrus; Experiment 1). On Day 13, animals were assigned to: control (only P-4 insert; 15 cows and 13 heifers) and iP4 (P-4 insert+100 mg iP(4); 13 cows and 12 heifers) groups, and submitted to daily ovarian ultrasonography and blood collection (Day 13 to Day 22). In Experiment 2, 760 suckled cows and 498 heifers were submitted to a TAI on Day 0 and assigned into control and iP4 groups on Day 13. In animals with luteolysis on Day 22, there was a second TAI on Day 24, and on Day 37 were subjected to the opposite treatments as imposed in first resynchronization procedure. On Day 37, there was pregnancy diagnosis in animals with functional CL. The third TAI was performed on Day 48. Day of follicular wave emergence did not differ between groups and parities. Dominant follicles were larger in cows than heifers, and in animals of the control group on Day 24. Greater P-4 concentrations were detected on Day 14 and Day 15 in the iP(4)-treated animals. Luteolysis occurred earlier in cows than heifers. Overall P/AI percentage as a result of second and third TAIs, regardless of parity, was greater in iP(4)-treated animals. In conclusion, females treated with a supplementary iP4 had a greater plasma P-4 concentration and P/AI, but there was no effect of iP(4) treatment on synchrony of timing of follicular wave. Univ Sao Paulo, Sch Vet Med & Anim Sci, Dept Anim Reprod, Sao Paulo, Brazil Sao Paulo State Univ, Sch Vet Med & Anim Sci, Dept Anim Prod, Botucatu, SP, Brazil Qualittas Genet Enhancement, Aparecida De Goiania, Go, Brazil Zoetis Anim Hlth, Sao Paulo, SP, Brazil Sao Paulo State Univ, Aracatuba Vet Med Coll, Sao Paulo, Brazil Sao Paulo State Univ, Sch Vet Med & Anim Sci, Dept Anim Prod, Botucatu, SP, Brazil Sao Paulo State Univ, Aracatuba Vet Med Coll, Sao Paulo, Brazil FAPESP: 2015/10606-9 FAPESP: 2018/20058-7

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.

Early embryonic development occurs in the oviduct, where an ideal microenvironment is provided by the epithelial cells and by the oviductal fluid produced by these cells. The oviductal fluid contains small extracellular vesicles (sEVs), which through their contents, including microRNAs (miRNAs), can ensure proper cell communication between the mother and the embryo. However, little is known about the modulation of miRNAs within oviductal epithelial cells (OECs) and sEVs from the oviductal fluid in pregnant cows. In this study, we evaluate the miRNAs profile in sEVs from the oviductal flushing (OF-sEVs) and OECs from pregnant cows compared to non-pregnant, at 120 h after ovulation induction. In OF-sEVs, eight miRNAs (bta-miR-126-5p, bta-miR-129, bta-miR-140, bta-miR-188, bta-miR-219, bta-miR-345-3p, bta-miR-4523, and bta-miR-760-3p) were up-regulated in pregnant and one miRNA (bta-miR-331-5p) was up-regulated in non-pregnant cows. In OECs, six miRNAs (bta-miR-133b, bta-miR-205, bta-miR-584, bta-miR-551a, bta-miR-1193, and bta-miR-1225-3p) were up-regulated in non-pregnant and none was up-regulated in pregnant cows. Our results suggest that embryonic maternal communication mediated by sEVs initiates in the oviduct, and the passage of gametes and the embryo presence modulate miRNAs contents of sEVs and OECs. Furthermore, we demonstrated the transcriptional levels modulation of selected genes in OECs in pregnant cows. Therefore, the embryonic-maternal crosstalk potentially begins during early embryonic development in the oviduct through the modulation of miRNAs in OECs and sEVs in pregnant cows.

We aimed to compare the effect of three estradiol benzoate (EB) doses on follicular wave emergence (FWE) and dominant follicle growth of suckled Nelore cows submitted to TAI (D0). On a random day of estrous cycle (D−10), multiparous (MULT; n=36) and primiparous (PRIM; n=20) suckled Nelore cows received an intravaginal progesterone (P4) device and were assigned in three groups. Cows in the EB-1 (n=20), EB-1.5 (n=15) or EB-2 (n=21) groups received, respectively, an im treatment with 1, 1.5 or 2 mg EB. A subgroup (n=10-13 cows/group) were subject to daily ovarian evaluations from D−10 to D0. On D−2, P4 devices were removed, and all cows received the same treatment: 1 mg estradiol cypionate, 0.53 mg sodium cloprostenol, and 300 IU eCG. Statistical analyses were performed considering only the main effects of treatment group and parity order. The proportion of cows with a synchronized FWE and the moment of the FWE did not differ (p>0.05) among the treatment groups (overall: 80% [28/35] and 4.1 ± 0.4 days); however, the FWE occurred earlier (p=0.007) in MULT (3.8 ± 0.2 days) than PRIM (5.1 ± 0.4) cows. The proportion of animals detected in estrus was greater (86% [31/36] vs. 70% [14/20]; p=0.02) and the dominant follicle was larger on D−2 (9.7 ± 0.3 mm vs. 7.8 ± 0.7 mm; p=0.006) and D0 (11.9 ± 0.4 mm vs. 10 ± 0.5 mm; p=0.008) in MULT than PRIM cows. In conclusion, the three EB doses presented similar efficiency to synchronize the FWE in suckled Nelore cows. Moreover, a delayed FWE and smaller dominant follicle is observed in PRIM cows, contributing to the reduced reproductive performance in this parity category when using similar TAI protocols of MULT cows.

The aim of this work was to evaluate pregnancy rates (PR) and ovulatory characteristics of Nelore cows receiving PGF2α at the time of AI (artificial insemination) in a progesterone(P4)/estradiol-based timed-AI protocol. We also compared the effects of PGF2α treatment at AI in cows inseminated with conventional or sex-sorted semen, with the absence or expression of estrus. In experiment 1, a total of 701 suckled, multiparous Nelore cows from two commercial beef farms were submitted to the same protocol. All cows received a 12.5 mg (IM) injection of dinoprost tromethamine (Dinoprost; Lutalyse®; PGF treatment) at days 7 and 9 of a timed-AI protocol. Following P4 device removal (day 11; D11), AI was performed 48 h later with conventional or sex-sorted semen from two different sires. At AI, cows received an additional dose of 12.5 mg (IM) of Dinoprost (PGF treatment) or 2.5 mL (IM) of sterile saline (Control). Estrus behavior was determined at D11 by activation of an estrus detection device (Estrotect®). The overall PR was 32.8% (n = 348) at Farm 1 and 42.3% (n = 353) at Farm 2 (P = 0.01). Despite PR differences between farms, the same factors affected PR at Farms 1 and 2. Body condition score (P = 0.02), estrus behavior (P = 0.01), and type of semen (P < 0.001) were factors affecting PR. Conventional semen had a 2.73x greater chance of successful pregnancy than sex-sorted semen. Cows displaying estrus had a 2.5x greater chance of successful pregnancy than cows that did not display estrus. No treatment effect (P = 0.67) was detected in cows receiving conventional or sex-sorted semen. However, there was a tendency (P = 0.08) for an interaction between treatment (PGF or control) and estrus behavior (estrus or no estrus). PGF2α at the time of AI tended to increase PR of cows that did not display estrus (P < 0.10). In experiment 2, 29 suckled, multiparous Nelore cows were compared using B-mode and Doppler ultrasongraphy to assess the ovulatory characteristics of cows receiving the 12.5 mg (IM) injection of Dinoprost (PGF treatment) or saline solution (control) at D11. No significant effects of PGF2α treatment at D11 were observed in follicular characteristics and/or ovulation performance. It was concluded that fertility of sex-sorted semen was lower than conventional semen, regardless of the PGF2α treatment. The 12.5 mg treatment of Dinoprost at AI did not accelerate the occurrence of ovulation; however, it was interesting to note that PGF2α treatment at timed-AI appeared to increase the fertility of cows that did not display estrus, independent of semen type.

The effects of 17β‐estradiol (E2) or estradiol benzoate (EB) on PGF2α release were studied in bred-non-pregnant and pregnant Nelore beef heifers. The day of timed artificial insemination (TAI) was designated day 0 (D0), and a single treatment was given on D14. All heifers also received an intravaginal P4 device on D14, and were randomly assigned to three groups: Control (C, P4 device only, n = 12); E2 (1 mg E2 + 9 mg P4, n = 10); or EB (1 mg, n = 10). Blood samples were collected hourly for 8 hours after treatment (Hours 0–8) to measure plasma concentrations (pg/mL) of a PGF2α metabolite (PGFM). The P4 device was removed on D22 and pregnancy was diagnosed on D28. Pregnancy rate was not different among groups (C, n = 7/12; E2, n = 5/10; EB, n = 5/10). More (P 100 pg/mL) in E2 group (6/10) than in EB (1/10) and C (0/12) groups. Hourly concentration of PGFM for Hours 0 to 8 showed significant effects of group and hour and an interaction of group by hour but did not show an interaction of group or hour with pregnancy status. In preliminary post-hoc analyses, PGFM concentrations during Hours 0 to 8 and pulse characteristics were analyzed within each pregnancy status. For the non-pregnant heifers, a group-by-hour interaction was detected tentatively indicating an increase (P 0.1) between E2 (124 ± 23) and EB (110 ± 30) groups, but was greater (P 0.1) from the other groups. For pregnant heifers, no effects of group, hour, or their interaction were detected in PGFM concentrations during the hourly sessions, except that maximum PGFM concentration was greater (P

The corpus luteum (CL) is a temporary endocrine gland that plays a decisive role in the reproductive physiology of gilts. Recently, it has been suggested that exogenous factors may compromise the normal functioning of the CL. In the present study, we aimed to understand to what extent an acute and systemic challenge with lipopolysaccharide (LPS) on the day of estrus could compromise gene expression of gilts’ CLs housed in different welfare conditions. For this, we housed 42 gilts in three different housing systems: crates, indoor group pens, and outdoor housing. Then, we challenged six females from each group with LPS and eight with saline (SAL) on the day of estrus. After slaughtering the gilts on the fifth day after the challenge, ovaries were collected for gene expression analysis by RT-qPCR. Housing system and LPS challenge did not have a significant interaction for any genes evaluated; thus, their effects were studied separately. We identified significant (p < 0.05) downregulation of the angiogenic genes VEGF and FTL1 among LPS-challenged animals. Meanwhile, we also observed upregulation of HSD3B1 gene among LPS-challenged animals. We found that STAR and LHCGR genes were differentially expressed depending on the housing system, which indicates that the environment may affect adaptation capabilities. Our results indicate that an acute health challenge on the estrus day alters CL gene expression; however, the role of the housing system remains uncertain.

Since buffaloes are a seasonal, polyestrous species, optimizing reproduction during the non-breeding season is a key factor in increasing the reproductive and productive efficiency of herds. Ovum pick-up associated with in vitro embryo production and embryo cryopreservation is an alternative to reduce seasonal impacts. We studied the effects of seasonality in buffalo oocyte donors and embryo recipients during the favorable and non-favorable breeding seasons. Donors were evaluated for oocyte recovery and blastocyst production rate as dFBS (donors in favorable breeding season) or dNBS (donors in non-favorable breeding season). Embryos produced from dFBS or dNBS were cryopreserved by vitrification or the slow-freeze method for direct transfer and transferred to recipients in the favorable (rFBS) or non-favorable breeding season (rNBS). The heifers or cows were subjected to a fixed-time embryo transfer protocol and conception rates were determined on day 30 and on day 60. The oocyte recovery was lower in dFBS than in dNBS (7.6 vs. 10.0 oocyte/OPU, p = 0.0262); while no difference was found comparing blastocyst production rate (23.7% vs. 30.9% of blastocysts, respectively). Embryos from dFBS resulted in greater (p = 0.0013) conception rates on day 30 compared to dNBS (46.5% vs. 22.4%, respectively), despite the breeding season. The rFBS and rNBS treatments had similar (p = 0.6714) conception rates on day 30 (38.0% vs. 33.0%, respectively), indicating similar uterine receptivity. However, heifers on FBS had higher (p = 0.0003) conception rates on day 30 than cows (73.9% vs. 13.3%, respectively) when receiving embryos from dFBS. Vitrification and direct transfer had similar (p = 0.1698) conception rates on day 30 (30.4% vs. 41.4%, respectively). In conclusion, in vitro-produced embryos derived from dFBS were more competent in establishing pregnancy than dNBS counterparts, independent of recipients' reproductive seasonality. Heifers achieved better conception rates than cows during the favorable breeding season when the embryo came from dFBS. Cryopreserved in vitro produced embryos represent a reliable alternative to reduce seasonal variations in buffalo reproduction. The data elucidate the seasonal effects on embryo competence and on recipients’ uterine receptivity, affording new strategies to implement ovum pick-up associated with in vitro embryo production programs in buffalo herds.

Made available in DSpace on 2020-12-12T02:43:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-10-01 The aim of this research was to evaluate the effects of the temperament of bovine females Bos taurus indicus submitted to a timed artificial insemination (TAI) protocol on the concentrations of cortisol, diameter of the largest follicle, pregnancy by TAI on Days 30 (P/TAI 30) and 60 (P/TAI 60) after TAI. Nellore cows (n = 2702) of 45 ± 7 days post-partum were submitted to the same TAI protocol. On D -10 devices containing 1 g of progesterone were inserted into the vagina and 2 mg of estradiol benzoate were applied intramuscularly. On D -2, the devices were removed and 530 µg of sodium D-cloprostenol, 300 IU of equine chorionic gonadotropin, and 1 mg of Estradiol Cypionate were applied. Forty-eight hours after the final injection, the cows were submitted to TAI (D 0). The temperament of the cows was rated on a numerical scale from 3 to 12 using the composite reactivity score (RS) on D -10. The RS included the evaluation of the movement and breathing while the animal was in the cattle chute and the exit velocity. Cows were classified as Calm (RS ≤ 4; n = 830; Calm group), Reactive (RS = 5 to 8; n = 1313; Reactive group) and Very Reactive (RS ≥ 9; n = 559; Very Reactive group) and 5% of the cows of each group were submitted to blood collection for the subsequent plasmatic cortisol concentration measurement by ELISA. It was observed that Calm group had lower concentration of cortisol than did the Reactive and Very Reactive groups (35.07 ± 1.78, 50.58 ± 2.76, and 54.45 ± 3.39 nmol/L, respectively). The Calm group had diameter of the largest follicle on the day of TAI compared to Reactive and Very Reactive groups (14.4 ± 0.2, 13.6 ± 0.4, and 13.2 ± 0.2 mm, respectively). The Calm and Reactive groups had higher P/TAI compared to the Very Reactive Group on Day 30 (56.4%, 57.0%, 51.0%, respectively) and on Day 60 (50.0%, 47.3%, 42.7%, respectively). In conclusion, temperament influences the reproductive efficiency of bovine females Bos taurus indicus submitted to TAI protocols. University of São Paulo Faculty of Animal Science and Food Engineering, Duque de Caxias Norte Avenue, 255, Campus Fernando Costa, CEP 13.635-900 MF Vetplan, José Ferreira Street, 130, CEP 13.890-000 Boehringer Ingelheim Animal Health, Carlos Grimaldi Avenue, 1701, CEP 13.091-908 Biogénesis-Bagó Animal Health Ltda, Manoel Ribas Avenue, 985, CEP 80.810-000 São Paulo State University (UNESP) FCAT, Comandante João Ribeiro de Barros Road (SP 294), Km 651, CEP 17.900-000 University of São Paulo Faculty of Veterinary Medicine and Animal Science, Duque de Caxias Norte Avenue, 225, Campus Fernando Costa, CEP 13.635-900 University of Florida North Florida Research and Education Center Institute of Food and Agricultural Sciences São Paulo State University (UNESP) FCAT, Comandante João Ribeiro de Barros Road (SP 294), Km 651, CEP 17.900-000

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.

The objective of this experiment was to compare the expression of Interferon-tau Stimulated Genes (ISGs) in peripheral blood mono and polymorphonuclear cells (PBMCs and PMNs) in heifers following insemination. Twenty-nine Nelore heifers had estrous cycle synchronized, and FTAI occurred on D0. Pregnancy diagnosis was performed by ultrasonography on D28 post FTAI. On D0, 10, 14, 16, 18 and 20, blood (25mL) from the jugular vein was collected in heparinized tubes for isolation of PMNs and PBMCs. The isolation was performed using Ficoll®Paque Plus (GE Healthcare). PMNs and PBMCs samples from 8 pregnant and 9 non-pregnant heifers were subjected to RNA extraction using the DirectZol-RNA kit (Zymo-Research) and Trizol (Invitrogen), respectively. The expression of the target genes (ISG15, OAS-1, MX1 and MX2) was normalized in relation to the two reference genes (GAPDH/ACTB for PMNs and GAPDH/PPIA for PBMCs). The abundance of transcripts was evaluated by analysis of variance considering fixed effects of group, day and group by day interaction using the PROC MIXED procedure in SAS. PMNs and PBMCs had a similar expression profile of ISG15 and OAS-1, showing a relative increase (P < 0.05) from D18, and a significant increase in (P < 0.05) expression in pregnant compared to non-pregnant females on D18 and D20. These results were also observed for MX1 in PBMCs. In PMNs, no significant effects for MX1 were found. For MX2, in both cells types, only a group effect (P < 0.05) was observed, indicating a higher expression in pregnant heifers (0.57±0.11 vs. 0.21±0.03) on the days evaluated. When comparing the relative expression of the target genes to D0, no significant (P > 0.1) differences were found between PMNs and PBMCs. In summary, ISG expression is similar in PMNs and PBMCs, specifically for ISG15 and OAS-1, which both seem to be suitable biomarkers for potential early pregnancy determination in heifers.

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.

Follicular development and deviation processes during the postpartum period are not completely known in horses. Thus, we aimed to study the characteristics of follicular dynamics and ovarian vascular perfusion during the postpartum period in mares that demonstrated estrous behavior and had early (10 days) or late (≥10 days) postpartum ovulation. Ten mares were scanned daily by transrectal ultrasonography from the first day postpartum (d1) to the sixteenth day after the first postpartum ovulation (D0 = ovulation). The animals were split in the early (n = 3) and late (n = 7) ovulation groups (average interval between parturition and ovulation: 8.0 ± 0.0 and 14.7 ± 1.2 days, respectively). For the follicular growth, no difference (P 0.1) was detected between the groups when the data were normalized for the days preceding the first postpartum ovulation (from D-7 to D-1). However, when the data were normalized to days postpartum, the dominant follicle was larger (P 0.05) in the early-ovulated group in all days during this period (d1 to d7). The number of follicles25 mm diameter was greater (P 0.05) in the early-ovulated group during the first 3 days postpartum, and the late-ovulated mares showed greater number of follicles with 20-25 mm during d4 to d7. For blood flow characteristics, no difference (P 0.1) was detected between groups in vascular perfusion of the dominant follicle or in the ovarian pedicle ipsilateral to the largest follicle. Similarly, no difference (P 0.1) was detected in progesterone concentrations, corpus luteum (CL) area and vascular perfusion of the CL. Pregnancy rate did not differ (P 0.1) between the early (3/3; 100%) and late (5/7; 71.4%) groups. Therefore, the characteristics of the follicle growth on the preceding days of ovulation were similar between the early- and late-ovulated mares and were consistent with the follicular dynamics expected in non-pregnant and non-lactating mares. However, when the data were analyzed for the days relative to parturition, greater follicle development was present in mares that ovulate earlier during the postpartum period (10 days). The results suggest that important events may occur before parturition, resulting in early follicle development, mainly in those mares that show estrus and ovulate within 10 days postpartum.