Comparison of estradiol benzoate and cypionate in Girolando cows submitted to a timed artificial insemination

Abstract

The various studies on the manipulation of the estrous cycle culminated in the development of estrous and ovulation synchronization protocols, to the point of defining an optimum moment for artificial insemination. The induction of ovulation is a primordial part for the determination of the moment of the TAI, so to study which hormones and how they behave allows a better understanding of this physiological process and, to manipulate it efficiently. The aim of the present study was to compare the use of estradiol benzoate (EB) and cypionate (ECP) as ovulation inducer in Girolando cows submitted to Timed Artificial Insemination (TAI). Ovulations of 108 Girolando cows were synchronized and the initial day of treatment, recorded as D0, which was when the animals received an intravaginal device containing 1g of progestogen and an intramuscular application (im) of 2mg of EB. After 8 days (D8), the device was removed and 500μg of cloprostenol (im) was administered to all females. Then, the animals were randomly divided into two treatments: BG Group (n = 52) and CG Group (n = 56). The CG animals received 1mg of ECP (im) as the ovulation inducer at the time of device removal, while BG Group cows received 1mg of EB (im) 24 h later (D9). TAI occurred at D10. After device removal, ultrasound evaluations were performed every 12 h up to ovulation. The following reproductive parameters were evaluated: interval from intravaginal device removal to ovulation - IDO (hours); interval from ovulation to TAI-IOT (hours); diameter of the largest follicle at intravaginal device removal (mm); maximum diameter of the DF (mm) at D10; the dominant follicle growth rate (mm/day); synchronization rate - SR (%); ovulation rate - OR (%) and PR - pregnancy rate (%). Only the ovulation rate presented a statistical difference (p<0.05). In conclusion, despite the ovulation rate difference, both estradiol esters administered were effective and presented similar pregnancy rates in Girolando cows submitted to TAI.

Efficiency and accuracy of different ovulation inducers after progesterone device removal in crossbred multiparous cows

“…Ovulation of the dominant follicle (DF) depends on P4 exogenous source removal (after five to nine days of exposure), performed simultaneously with the application of an ovulation inducer (6) . Analogs (gonadorelin) or superanalogs (buserelin, lecirelin, and fertirelin) of gonadotropin-releasing hormone (GnRH), estradiol esters (7,8) (estradiol benzoate, EB; and estradiol cypionate, EC), prohibited in the European Community, despite their efficiency and cost-effectiveness (9) , human chorionic gonadotropin (hCG), and luteinizing hormone (LH) are some of the drugs used as inductors of ovulation (10) . Deslorelin (DES), a GnRH superagonist, is used in ovulation induction protocols in mares (11) and cows (12,13) .…”

Eficiência e acurácia de diferentes indutores de ovulação após a remoção do dispositivo de progesterona em vacas mestiças multíparas

“…A ovulação do folículo dominante (FD) depende da remoção da fonte de P4 exógena (após 5 a 9 dias de exposição) executada simultaneamente com a aplicação de um indutor da ovulação (6) . Análogos (gonadorelina) ou superanálogos (buserelina, lecirelina, fertirelina) do hormônio liberador de gonadotrofina (GnRH), ésteres do estradiol (7,8) (benzoato de estradiol, BE; e cipionato de estradiol, CE), proibidos na Comunidade Européia, a despeito da eficiência e custo-benefício (9) , gonadotrofina coriônica humana (hCG) e o hormônio luteinizante (LH) são alguns dos fármacos empregados como indutores da ovulação (10) . A deslorelina (DES), um superagonista do GnRH, é utilizada em protocolos de indução da ovulação em éguas (11) e em vacas (12,13) .…”