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Testamos em vacas leiteiras as hipóteses: 1) que iniciar a ressincronização da ovulação para inseminação artificial em tempo fixo (IATF) 17 dias após a IATF (Ressincronização Superprecoce) melhora a eficiência reprodutiva em comparação com a ressincronização tradicional iniciada aos 31 dias após a IATF; e 2) o tratamento com 1 mg de benzoato de estradiol (BE) no início da Ressincronização Superprecoce não compromete uma gestação pré-existente e reduz a taxa de falso positivos (FP) no diagnóstico precoce da gestação por meio da ultrassonografia Doppler. Vacas leiteiras de duas fazendas comerciais, com escore de condição corporal entre 2 e 4 (escala: 1-5), com período de espera voluntária de 52 dias, foram submetidas a um protocolo baseado em BE/progesterona (P4) para a primeira IATF pós-parto (D0). No D17, as vacas foram distribuídas aleatoriamente em três grupos experimentais (n=150/grupo): Controle (C); Ressincronização Superprecoce (SP) e Ressincronização Superprecoce + 1 mg BE (SP+BE). No diagnóstico de gestação convencional (31 dias após cada IATF), vacas não gestantes (NG) do grupo C foram submetidas ao mesmo protocolo hormonal feito no manejo reprodutivo da fazenda, sendo repetido para realizar três IATFs (D0, D42 e D84) no intervalo de 84 dias. Em ambos os grupos submetidos a Ressincronização Superprecoce, todas as vacas receberam um dispositivo intravaginal de P4 de primeiro uso (CIDR®, Zoetis, Brasil) associado (SP+BE) ou não (SP) a 1 mg BE (1 mL, i.m., Gonadiol®, Zoetis) 17 dias após cada IATF, sendo repetido até obter quatro possibilidades de IATFs em 84 dias. No D24, D52 e D80 as vacas foram avaliadas por ultrassonografia Doppler para determinar a perfusão sanguínea do CL e aquelas em que foi detectada luteólise foram consideradas NG e receberam uma dose de 25 mg dinoprost trometamina (5 mL, i.m., Lutalyse®, Zoetis). No D26, os dispositivos P4 foram removidos e foi administrado 1 mg de cipionato de estradiol (CE; 0,5 mL, i.m., ECP®, Zoetis) e 25 mg de dinoprost trometamina nas vacas consideradas NG. No D28 foi realizada uma segunda IATF (intervalo de 28 dias entre as IATFs). Ambos os tipos de ressincronização (Ressincronização Convencional ou Superprecoce) foram repetidos até D84, o que permitiu um máximo de 3 IATFs no grupo C e 4 IATFs nos grupos SP e SP+BE. O diagnóstico confirmatório de gestação foi realizado nos dias 31 e 66 após a primeira, segunda, terceira e quarta IATF. Os dados foram avaliados por ANOVA, teste exato de Fisher e regressão logística do SAS. A taxa de prenhez (TP) na primeira IATF não diferiu (P>0,1) entre os grupos C (44%), SP (47%) e SP+BE (47%). Vacas submetidas à Ressincronização Superprecoce apresentaram maior (P0,1) entre os grupos C (29,6% [42/142]), SP (30,3% [44/145]) e SP+BE (30,2% [48/159]); entretanto, a TP acumulada nos 84 dias do período experimental foi maior (P=0,05) nas vacas submetidas à Ressincronização Superprecoce (79,3% [238/300]) em relação ao grupo C (72% [108/150]). Além disso, a taxa de resultados de FP entre o diagnóstico por Doppler e o diagnóstico confirmatório de gestação foi menor (P0.1) among the C (44%), SP (47%) and SP+BE (47%) groups. Cows submitted to Super-early Resynch had a greater (P0.1) among the C (29.6% [42/142]), SP (30.3% [44/145]) and SP+BE (30.2% [48/159]) groups; however, cumulative PR within the 84 days of experimental period was greater (P=0.05) in cows submitted to Super-early Resynch (79.3% [238/300]) compared to the C group (72% [108/150]). Furthermore, the rate of FP results between the D24 and confirmatory pregnancy diagnosis on D31 was lesser (P

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

We aimed to compare the effects of use of 1 or 2 mg estradiol benzoate (EB) associated with an intravaginal progesterone (P4) device for resynchronization of ovulation 14 days after timed-AI (TAI) in suckled beef cows. Nelore cows were submitted to a TAI (D0) and on D14, received an intravaginal P4 device and were randomly assigned to EB-1 group [n = 516] or EB-2 group [n = 510], which that received 1 or 2 mg EB, respectively. Also, cows had the ovaries scanned by ultrasound to detect an active CL on D14. On D22, devices were removed and structural luteolysis was detected by color-Doppler ultrasonography. In cows which underwent luteolysis, the resynchronization protocol was continued and they were submitted to second TAI on D24. Pregnancy diagnosis was performed 30-35 days after first or second TAI. A subgroup [n = 18-19/group] was submitted to daily ovarian ultrasound scanning from D14 to D22. Proportion of cows with an active CL on D14 did not differ (P 0.1) between EB-1 and EB-2 groups. The proportion of cows with an active CL on D22 and pregnancy per AI (P/AI) at first TAI were greater (P ≤ 0.05) in EB-1 (55% and 51%) than in EB-2 group (48% and 42%). The P/AI at second TAI did not differ (P 0.1) between EB-1 (47% [106/227]) and EB-2 group (42% [110/259]). Cumulative pregnancy rate was greater in EB-1 (73% [370/508]) than in EB-2 group (64% [322/502]). No difference (P 0.1) was observed in the proportion of non-pregnant cows with a synchronized follicular wave emergence between EB-1 and EB-2 groups. In conclusion, treatment with either 1 or 2 mg EB associated with an intravaginal P4 device at D14 after TAI are efficient to synchronize a new follicular wave emergence. The decreased P/AI from first TAI observed in the group of cows receiving 2 mg indicates that this dose is not recommended for use in resynchronization programs initiated 14 days after TAI. The use of 1 mg EB associated with a P4 device provides an elevated cumulative pregnancy rate after two TAIs with an interval of 24 days.

In cattle, uterine luminal fluid (ULF) is the main source of molecules that support embryo development and survival during the peri-implantation period. Overarching hypothesis was that peri-estrus changes in ULF volume through accumulation and resorption mechanisms influence ULF composition during the estrous cycle and early pregnancy. Objectives were (1) to characterize individual temporal and spatial changes in ULF volume, endometrial and luteal vascularity, endometrial and luteal size, and progesterone (P4) concentrations during the peri-estrus period in beef heifers and, (2) associate such changes with the metabolite composition in the ULF, four days after estrus. Fourteen Bos indicus heifers 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 (estrus = d 0). Plasma P4 was measured daily. On d 4, the uterine body was sampled using a cytology brush for targeted metabolomic analysis by mass spectrometry. Multivariate analyses clustered heifers according to ovarian, uterine, and hormonal variables in clusters A (n = 5) and B (n = 8 heifers). Individual metabolite concentrations were compared between clusters A and B by univariate analysis using t-test after FDR correction. 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 non-essential AA, sum of aromatic AA, and total AA were greater in cluster A (FDR ≤ 0.05). ULF volume dynamics and associated uterine, ovarian, and hormonal variables during the peri-estrus period presented a concerted variation among heifers, which was associated with the ULF composition four days after estrus. Potential implications for embryo receptivity and reproductive outcomes are the focus of the current investigation.

In cattle, early development of the non-attaching embryo depends exclusively on the biochemical properties of the intrauterine milieu. As the embryo transitions from the oviduct to the tip of the uterine horn around 4 days after oestrus, little is known about uterine functions that modulate the milieu composition and potentially determine pregnancy success. The objective was to characterise changes in uterine luminal fluid (ULF) accumulation and absorption, endometrial vascularity, and endometrial thickness in response to progesterone fluctuations during the peri-ovulatory period in beef heifers. Fourteen Bos indicus heifers that presented a prostaglandin F2α (PGF2α) responsive CL received 500µg of PGF2α analogue i.m. (PGF) and were examined daily by rectal B-mode and pulse-wave colour-Doppler ultrasonography until the fifth day after oestrus (oestrus=Day 0). Plasma progesterone (P4) concentrations were measured daily. Uterine luminal fluid score was given based on the accumulation of fluid throughout the entire organ (0, no fluid, to 4). Measurement of the main ovarian structures, endometrial thickness, uterine luminal fluid score, and luminal fluid area of the cranial portion of the uterine horn ipsilateral to the preovulatory follicle and subsequent CL were executed by B-mode ultrasonography and endometrial vascularity by colour Doppler. The fixed effect of day was analysed by ANOVA. There was an effect of day on endometrial vascularity, endometrial thickness, and uterine luminal fluid score (P≤0.01) as well as uterine luminal fluid area (P≤0.05). Endometrial vascularity and endometrial thickness increased after PGF injection to peak on Day −1, whereas uterine fluid score peaked on Day 0. Interestingly, cranial uterine luminal fluid area peaked twice, on Day −1 and Day 5. Vascularity, thickness, and fluid accumulation decreased gradually from Day 0 to Day 5. There was a negative correlation (r=−0.55) between the sum of daily P4 concentrations during proestrus (i.e. from PGF to oestrus) and the greatest ULF score measured (P=0.05). Length of proestrus was correlated negatively (r=−0.69) with the increase in uterine body thickness during proestrus (P=0.03). The sum of daily luminal fluid scores, from PGF injection to Day 5, was double for heifers grouped within the upper third for that variable compared with those grouped within the lower third. In conclusion, peri-ovulatory transformations in uterine morphology and function are dramatic and vary in duration and in intensity among animals. Temporal changes in intraluminal fluid accumulation and absorption at the site of embryo arrival may change its biochemical composition. Potential implications for embryo receptivity and reproductive outcomes deserve further investigation.