Redução da dose da gonadotrofina coriônica equina por meio da farmacopuntura em vacas mestiças leiteiras submetidas a protocolos de IA em tempo fixo

Abstract

The pharmacopuncture allows reduces drug dose and minimizes hormone therapy costs. The aim of this study was to evaluate the effect of equine chorionic gonadotropin (eCG) reduced dose during ovulation synchronization in fixed-time artificial insemination protocol (FTAI). For this, 33 crossbred bovine females were submitted to transrectal ultrasound examination (US), ten days before (D10) starting the ovulation synchronization protocol. On day zero (D0), a fixed-time AI (FTAI) protocol was initiated by inserting the intravaginal progesterone (P4) implant, associated with the application of 2.0mg estradiol benzoate and 12.5mg dinoprost tromethamine intramuscularly. On day eight (D8), the intravaginal P4 implant was removed and 12.5mg dinoprost tromethamine and 1 mg estradiol cypionate (EC) were administered to all animals, intramuscularly. On D8, the intravaginal P4 device was removed and 12.5mg dinoprost tromethamine and 1mg estradiol cypionate (EC) were administered to all animals, intramuscularly. Then, the females were randomly distributed in three groups: Group 1 (control) (n = 11) were administered 300IU eCG (im); Group 2 (reduced dose) (n =1 0) were administered 100IU eCG (im) and Group 3 (reduced dose) (n = 12) were administered 100IU eCG in Baihui acupoint. During the follicular dynamics, US examinations were performed, in mode B and power-flow, every 12 h from D8 to ovulation, which occurred until D10. During the follicular dynamics period were measure follicular diameter (FD), follicular growth rate from D8 to D10 (FGRD8-D10), the follicular wall area (FWA), the blood perfusion area of the follicular wall (BPAFW) and the blood perfusion percentage in the area of the follicular wall (PBPAFW). In D24, during the luteal phase, the following variables were measured: luteal diameter (DCL); luteal area (ACL); CL blood perfusion area (BPACL) and percentage of blood perfusion in the CL area (BPPACL), also with the aid of US mode B and power flow. Blood samples were collected to measure serum P4 concentrations on day 8; 10 and 24. Data were submitted to ANOVA test and average was compared by Tukey test and a significance level of P ≤ 0.05 was considered. There were no significant differences between the synchronization protocols for all variables tested during the follicular dynamics, but Group 3 showed a tendency in relation to Group 2, as it presented higher FD in D10 (P = 0.06) and a larger preovulatory follicle diameter xiii (P = 0.09), as well as in BPAFW 8 (P = 0.07) and in the percentage of BPAFW 8 (P = 0.07). The experimental groups presented similar preovulatory serum P4 concentrations at each moment of the evaluation (P > 0.05), demonstrating homogeneity among them. There was no significant difference between synchronization protocols for the above-mentioned post ovulatory luteal variables. These results indicate that Baihui acupoint was effective as an alternative route for eCG dose reduction, without detriment to reproductive rates, in FTAI protocols without negatively affecting reproductive rates in crossbred dairy cows, reducing the costs of this biotechnology.