Impact of 17ß-estradiol administration at the moment of timed-AI in Nelore cows with small dominant follicle or not showing estrus.

We aimed to evaluate the effects of administering estradiol (E-17ß) at the moment of timed-AI (TAI) on uterine gene expression, estrous expression rate (EER), and pregnancy rate (P/TAI) in Nelore cows with a small dominant follicle (DF) or not showing estrus at TAI. In Experiments 1 and 2 (Exp1, Exp2) cows were submitted to a P4/E-17ß-based protocol (day 0) for synchronization of ovulation. On day 7, devices were removed, cows received 1 mg E-17ß cypionate and 12.5 mg dinoprost. On day 9, cows with DF < 11.5 mm in diameter were split into different groups. In Exp1 (n = 16/group): Control (no treatment), E-2 (2 mg E-17ß) and E-4 (4 mg E-17ß). In Exp2: Control (n = 12); E-2 (n = 14); GnRH (0.1 mg gonadorelin acetate, n = 13); and E-2+GnRH (association of GnRH and E-17ß, n = 13). Between days 9 and 11, endometrial thickness (ET), time of ovulation detection, and EER were recorded. In Exp1, a uterine cytological sample was collected 4 h after treatment to evaluate the transcript expression of receptors for E-17ß (ESR1 and ESR2), oxytocin (OXTR), and P4 (PGR). In Experiment 3 (Exp3), 3829 suckled cows were submitted to a P4/E-17ß-based protocol for TAI. On day 9, devices were removed and cows received 1 mg E-17ß cypionate and 0.4 mg sodium cloprostenol. On day 11, TAI was performed and cows that did not demonstrate estrus received 0.1 mg gonadorelin acetate, and were allocated into two groups: GnRH (n = 368) and E-2+GnRH (2 mg E-17ß; n = 363). In Exp1, plasma E-17ß concentrations increased at 4 h after treatment in a dose-dependent manner but reduced at 12 h. The E-17ß-treated cows had greater transcript abundance for OXTR and lesser for ESR1 and ESR2, and the ET was reduced 12 h after treatment (P < 0.05). No significant difference (P > 0.1) was observed between the E-17ß doses in estrus or ovulation rate. In Exp2, the interval from treatment to ovulation was longer (P < 0.05) in the E-17ß group. GnRH-treated cows showed higher ovulation rates (89 vs. 35 %) compared to cows not treated with GnRH, as E-17ß-treated cows (P < 0.01) had a lower ovulation rate compared to those not receiving E-17ß (44 vs. 78 %). In Exp3, P/TAI was 55 % for cows in estrus. For those not showing estrus, no difference (P > 0.1) in P/TAI was observed between GnRH (34 %) and E-2+GnRH (31 %) groups. Cows with a DF ≥ 11 mm (n = 192) had a greater (P < 0.05) P/TAI (49 %) than those with DF < 11 mm (n = 377; 29 %). In conclusion, E-17ß administration in the moment of TAI modulates the mRNA expression of uterine receptors in cows with a small DF but does not impact the P/TAI compared with GnRH treatment in suckled Nelore not showing estrus previous to TAI.

Use of Doppler ultrasonography for selection of recipients in embryo transfer programs in horses.

We aimed to evaluate the impact of corpus luteum (CL) and uterine characteristics accessed by B-mode and Color-Doppler ultrasonography in recipient mares at the time of embryo transfer (ET) on pregnancy outcomes. Recipient mares (n = 110), between days 3-9 after spontaneous ovulation, received a fresh embryo. Immediately before ET, the reproductive system was assessed by transrectal palpation for the following parameters: uterine tone (0-3), CL echogenicity (0-6), CL type (homogeneous, trabecular or anechoic center), luteal area (cm2), uterine echogenicity (0-3), uterine edema (0-3), luteal blood perfusion (0-100%) and uterine blood perfusion (1-4). Additionally, a blood sample was collected by puncture of the jugular vein for plasma P4 dosage. Retrospectively, recipients were classified according to the luteal area (small [≤ 6 cm2] or large [> 6 cm2]), luteal blood perfusion (low [≤ 55%] or high [> 55%]), and plasma concentration of P4 (low ≤ 9.98 ng/mL or high > 9.98 ng/mL). Pregnancy diagnosis was performed at 12 and 30 days of gestation. Luteal blood perfusion was significantly higher (P = 0.04) in pregnant recipients (n = 83) than in non-pregnant recipients (n = 27). Overall P/ET was higher (P ≤ 0.02) in mares with high luteal blood perfusion and high P4. Luteal blood perfusion was the most adequate significant (P = 0.01) predictor of pregnancy compared with the luteal area and plasma P4 concentration. Only luteal blood perfusion showed a linear (P = 0.03) and cubic (P = 0.004) effect on P/ET. In conclusion, CL blood perfusion determined by color-Doppler can be used in real-time to select recipients with the greatest chance of maintaining pregnancy in equine ET programs.

Conjugated linoleic acid supplementation changes prostaglandin concentration ratio and alters the expression of genes involved in maternal-fetal recognition from bovine trophoblast cells in vitro.

Early embryonic mortality caused by maternal-fetal recognition failure in the three weeks after fertilization represents a major cause of reproductive inefficiency in the cattle industry. Modifying the amounts and ratios of prostaglandin (PG) F2α and PGE2 can benefit the establishment of pregnancy in cattle. Adding conjugated linoleic acid (CLA) to endometrial and fetal cells culture affects PG synthesis, but its effect on bovine trophoblast cells (CT-1) is unknown. The aim of this study was to determine the effects of CLA (a mixture of cis- and trans-9, 11- and -10,12-octadecadienoic acids) on PGE2 and PGF2α synthesis and the expression of transcripts involved with maternal-fetal recognition of bovine trophectoderm. Cultures of CT-1 were exposed to CLA for 24, 48 and 72 h. Transcript abundance was determined by qRT-PCR and hormone profiles were quantified by ELISA. The PGE2 and PGF2α concentrations were reduced in the culture medium of CLA-exposed CT-1 compared to that of unexposed cells. Furthermore, CLA supplementation increased the PGE2:PGF2α ratio in CT-1 and had a quadratic effect (P < 0.05) on the relative expression of MMP9, PTGES2, and PTGER4. The relative expression levels of PTGER4 were reduced (P < 0.05) in CT-1 cultured with 100 µM CLA than in the unsupplemented and 10 µM-CLA groups. Treatment of CT-1 with CLA decreased PGE2 and PGF2α synthesis but a biphasic effect of CLA was observed on the PGE2:PGF2α ratio and relative abundance of transcripts with 10 µM CLA providing maximal improvements in each endpoint. Our data suggest that CLA may influence eicosanoid metabolic process and extracellular matrix remodeling.

Effects of recombinant bovine somatotropin on pregnancy per artificial insemination, corpus luteum cellular composition and endometrial gland morphometry in beef cattle.

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 ±â€¯0.84 ng/mL) than bST 0 (9.83 ±â€¯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 ±â€¯0.32 vs. 2.25 ±â€¯0.20 g); however, the bST 0 treatment heifers had a greater percentage of LLC than did the bST 500 treatment (13.72 ±â€¯1.16% vs. 8.60 ±â€¯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.