182 Hormonal profile during resynchronisation using oestradiol benzoate and progesterone-based protocols associated or not with flunixin meglumine in cattle
L. Siqueira A , R. Sequeto B , R. Anunciação C , L. Camargo A , C. Fernandes C , J. Fonseca D , L. Pfeifer E and J. Viana FA Embrapa Gado de Leite, Juiz de Fora, MG, Brazil
B Universidade Federal de Juiz de Fora, Juiz de Fora, MG, Brazil
C Universidade José do Rosário Vellano, Alfenas, MG, Brazil
D Embrapa Caprinos e Ovinos, Sobral, CE, Brazil
E Embrapa Rondônia, Porto Velho, RO, Brazil
F Embrapa Recursos Genéticos e Biotecnologia, Brasília, DF, Brazil
Reproduction, Fertility and Development 35(2) 218-219 https://doi.org/10.1071/RDv35n2Ab182
Published: 5 December 2022
© 2023 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of the IETS
A potential strategy to reduce inter-insemination intervals is to identify nonpregnant females on D20 based on CL blood flow (colour-Doppler ultrasound) associated with a resynchronisation (RESYNCH) protocol beginning during diestrus, on D12 (D0 = oestrus), and artificial insemination of open females on D22. Flunixin meglumine (FLU) is a nonsteroidal anti-inflammatory drug that inhibits prostaglandin synthase and antagonise oestradiol-related actions upon oxytocin endometrial receptors. The objectives were to: (1) determine whether oestradiol benzoate (EB) and a progesterone device (P4) given on D12 would change circulating oestradiol (E2) and disturb CL function (plasma P4); and (2) evaluate whether FLU treatment could prevent presumed detrimental effects of EB on CL. Lactating Holstein × Gir cows (n = 45) were submitted to an EB-P4-based ovulation synchronisation protocol (D10: 2 mg EB + P4 intravaginal device; D2: device removal + PGF2α; D1: 1 mg EB; D0: oestrus). On D12, cows were randomly allocated into four groups/treatments: (A) control (CTL), saline im; (B) 2 mg EB im, P4 device (EB-P4); (C) 2 mg EB im, P4 device, 1.1 mg/kg FLU im (EB-P4-FLU); and (D) P4 device on D12, dominant follicle ablation by OPU on D15 (OPU-P4). Blood samples were collected daily, and plasma was stored at −20°C. Solid-phase RIA was used to determine daily plasma P4 (D12 to D22; ImmuChem, ICN Pharmaceuticals Inc.) and plasma E2 at 48 h intervals (D13 to D21; Ultra-sensitive Oestradiol, Beckman Coulter Inc.). Data were analysed using PROC MIXED of SAS accounting for repeated measures. Main effects were group, day of cycle, and their interaction. Overall, we observed an effect of group (P = 0.0075 and P = 0.0068), day of cycle (P < 0.0001 and P < 0.001), and interaction group × day (P = 0.0001 and P = 0.0012) for both E2 and P4, respectively. On D13, EB-P4 and EB-P4-FLU had higher E2 compared with OPU-P4 and CTL (21.7 ± 2.7, 18.0 ± 3.4 vs 3.7 ± 0.9, and 8.76 ± 6.3 pg/mL, respectively; P < 0.001). Plasma E2 did not differ among groups or days from D15 onwards. Plasma P4 decreased from D12 to D22 in all groups; however, the rate of decrease differed. In groups receiving EB, P4 decreased from D12 to reach significant lower values on D17 (3.6 ± 0.3 vs 1.4 ± 0.2 ng/mL and 4.2 ± 0.4 vs 1.9 ± 0.4 ng/mL for EB-P4 and EB-P4-FLU, respectively; P < 0.0001), whereas plasma P4 decreased to lower values only on D20 in OPU-P4 (4.0 ± 0.3 vs 1.5 ± 0.3 ng/mL, D12 vs D20, respectively; P < 0.0001) and D19 in CTL (3.1 ± 0.4 vs 1.3 ± 0.4 ng/mL, D12 vs D19; P = 0.0045). In OPU-P4, plasma P4 peaked on D17 (4.0 ± 0.6 ng/mL) and remained high on D18 (3.2 ± 0.5), greater (P < 0.03) than for EB-P4 (1.4 ± 0.2 and 1.0 ± 0.2; D17 and D18) and EB-P4-FLU (1.9 ± 0.4 and 1.3 ± 0.4, respectively). In conclusion, RESYNCH using EB on D12 increased plasma E2 on D13 and may have anticipated functional luteolysis. Concomitant FLU treatment did not prevent this effect. Follicle ablation on D15 increased P4 48 h later, most likely by luteinisation of the aspirated follicle cells.
This research was supported by CNPq (Project 422372/2018-8) and FAPEMIG.
