Effect of estradiol cypionate and amount of progesterone in the intravaginal device on synchronization of estrus, ovulation and on pregnancy rate in beef cows treated with FTAI based protocols.
Three experiments were conducted to evaluate the effect of estradiol cypionate (ECP) and amount of progesterone in the intravaginal device (PID) on synchronization of estrus and ovulation, follicular dynamics, luteal dynamics and function and on pregnancy rate in beef cows treated with fixed-time artificial insemination (FTAI) based protocols. In Experiment 1, we evaluated the synchronization of ovulation using 1mg of ECP at PID removal (day 8 after PID insertion) or 1mg of estradiol benzoate (EB) 24h later, in cows treated with 0.558 or 1g of progesterone (P4). The final subgroups were: 0.558g+ECP: n=10; 0.558g+EB: n=11; 1g+ECP: n=10; 1g+EB: n=10. Ovarian ultrasonic examinations were performed to detect the dominant follicle and ovulation. There was no effect of treatments on the diameter of dominant follicle at any time, and on the mean interval to estrus and to ovulation (P>0.05); however, ECP treated cows had scattered distribution of estrus (P<0.03) and ovulation (P<0.03). In Experiment 2, cows received the following treatments: 0.558gP4+ECP: n=52; 0.558gP4+EB: n=52; 1gP4+ECP: n=50; 1gP4+EB: n=52; and FTAI. Pregnancy rate did not differ (P>0.05) between progesterone content (0.558g: 52.9%, 55/104; 1g: 56.9%, 58/102) but differed between estradiol esters (P<0.05; ECP: 48.9%, 49/102; EB: 61.5%, 64/104). In Experiment 3, cows received: 0.558gP4+ECP: n=55; 0.558gP4+EB: n=53; 1gP4+ECP: n=54; 1gP4+EB: n=53; and FTAI. Pregnancy rate did not differ (P>0.05) between progesterone content (0.558g: 48.1%, 52/108; 1g: 53.3%, 57/107) and estradiol esters (ECP: 47.7%, 52/109; EB: 53.8%, 57/106). In conclusion, ECP administration at device removal and progesterone content of PID has no influence on the synchronization of estrus, follicular dynamics, luteal dynamics and function. However, ECP administration affected the synchronization of ovulation and pregnancy rate in non-suckling beef cows, but did not affected pregnancy rate in suckling beef cows. Future studies should evaluate the distribution of ovulations in suckling Bos taurus beef cows.
Postgraduate student, CONICET fellowship, Universidad Nacional del Centro de la Provincia de Buenos Aires, Facultad de Ciencias Veterinarias, Tandil, Argentina; Área de Reproducción, Facultad de Ciencias Veterinarias, Universidad Nacional del Centro de la Provincia de Buenos Aires, Tandil, Argentina. Electronic address: uslenghi@vet.unicen.edu.ar.
Gastón
G
Uslenghi
Veterinary, private activity in Grupo CONPAS, Rauch, Provincia de Buenos Aires, Argentina.
Santiago González
SG
Chaves
Área de Reproducción, Facultad de Ciencias Veterinarias, Universidad Nacional del Centro de la Provincia de Buenos Aires, Tandil, Argentina.
Jorge
J
Cabodevila
Área de Reproducción, Facultad de Ciencias Veterinarias, Universidad Nacional del Centro de la Provincia de Buenos Aires, Tandil, Argentina.
Santiago
S
Callejas
D000282:Administration, Intravaginal; D000818:Animals; D002417:Cattle; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000008:administration & dosage / Q000031:analogs & derivatives*; D004973:Estrus Synchronization / Q000379:methods*; D005260:Female; D007315:Insemination, Artificial / Q000379:methods* / Q000662:veterinary; D007434:Intrauterine Devices; D010060:Ovulation / Q000187:drug effects*; D011247:Pregnancy; D018873:Pregnancy Rate; D011270:Pregnancy, Animal; D011374:Progesterone / Q000008:administration & dosage*; D013997:Time Factors
D011374:Progesterone; D004958:Estradiol; C007630:estradiol 17 beta-cypionate
Beef cows; Estradiol cypionate; FTAI; Ovulation synchronization; Pregnancy; Progesterone