The main objective of this project was to develop an efficient methodology for the super-early resynchronization of non-pregnant females after Fixed-Time Artificial Insemination (FTAI) in dairy cattle. Super-early resynchronization strategies were studied using estradiol and progesterone (P4) on the 12th day after FTAI procedure, with or without the addition of non-steroidal anti-inflammatory drugs (NSAIDs), diagnosis of early pregnancy with Doppler on the 20th day based on blood flow in the corpus luteum (CL), and an interval between FTAIs of 22 days. The central hypothesis of this research was that the administration of non-steroidal anti-inflammatory drugs on the 12th day after FTAI, concomitantly with treatment with exogenous estradiol and P4, would minimize the potential deleterious effects of these hormones on CL function. Experiment 1 was carried out as a proof of concept to determine the effects of these hormones on morphological and functional characteristics of the CL during diestrus. It was conducted at the José Henrique Bruschi Experimental Field at Embrapa Dairy Cattle, in the municipality of Coronel Pacheco-MG, with multiparous cows (n=45), synchronized using a conventional ovulation synchronization protocol to perform the 1st FTAI. On the 12th day after the 1st FTAI, the animals were allocated into four groups with the following treatments: 1) Control Group; 2) 1 mg of BE (Estradiol Benzoate) and P4 implant on the 12th day (BE-P4); 3) 1 mg of BE and P4 implant and administration of NSAID (1.1 mg/Kg live weight i.m. of Funixin meglumine) on the 12th day (BE-P4-NSAID); and 4) Aspiration of the dominant follicle on the 15th day and insertion of a P4 intravaginal implant (OPU-P4 = ovum pick-up or transvaginal follicular aspiration – P4). Follicular dynamics and luteal development were monitored daily by B-mode and Doppler ultrasound. Blood samples were collected daily between the 12th and 22nd days for hormonal measurements by RIA (Radioimmunoassay). Continuous variables were studied using analysis of variance (ANOVA), as repeated measures over time, using the PROC MIXED procedure in the SAS software. Effects of group, cycle day and interaction between group and day were observed for estradiol (E2) and plasma P4 concentrations. On the 13th day, BE-P4 and BE-P4-NSAID had higher E2 compared to OPU-P4 and Control. Plasma E2 concentration did not differ among groups from the 15th day onwards. Plasma P4 reduced from the 12th to the 22nd day in all groups; however, the rate of decline in P4 differed. In groups receiving BE, P4 decreased from the 12th day onwards and reached significantly lower values on Day 17, while plasma P4 reached low values only on the 20th day in the OPU-P4 group and on the 19th day in the Control group (12th day vs 19th day). In the OPU-P4 group, plasma P4 peaked on the 17th day and remained high on the 18th day, higher than for the BE-P4 (17th and 18th days) and BE-P4-NSAID groups. The results indicated that resynchronization with BE on the 12th day increased the plasma E2 concentration on the 13th day and may have caused anticipation of functional luteolysis. The inclusion of non-steroidal anti-inflammatory drugs in the resynchronization protocol had no effect on circulating estradiol concentrations after exogenous application of estradiol benzoate. In this project, we were able to identify and characterize important changes during resynchronization and the endocrine consequences of early resynchronization using exogenous estradiol and progesterone. The results we achieved indicated that the inclusion of non-steroidal anti-inflammatory drugs in the resynchronization protocol did not have a beneficial effect on circulating concentrations of estradiol after exogenous application and did not prevent a transient increase in this hormone in the plasma of females undergoing resynchronization protocols started on the 12th day of the cycle. The information presented in this document contributes to achieving the Sustainable Development Goals (SDGs) number 1 - Eradication of poverty: End poverty in all its forms, everywhere; 2 - Eradication of hunger: End hunger, achieve food security and improved nutrition and promote sustainable agriculture; and 8 - Dignified employment and economic growth: Promoting growth sustained, inclusive and sustainable economic development, full and productive employment, and decent work for all.