Efeito do eCG ou benzoato de estradiol associado ao norgestomet na taxa de concepção de vacas de corte submetidas à IATF no pós-parto | Effect of eCG or estradiol benzoate associated with norgestomet on the conception rate of beef cows submitted to FTAI in the postpartum

Portugués. Este estudo objetivou comparar as taxas de concepção, em vacas de corte no período pós-parto (PPP), tratadas com Gonadotrofina Coriônica Eqüina (eCG) ou Benzoato de Estradiol (BE), após o uso de Norgestomet submetidas à inseminação artificial em tempo fixo (IATF). A hipótese é que a administração de eCG ou BE aumenta as taxas de concepção. Vacas Nelore (n=138) e Brangus (n=63), lactantes, entre 26 e 118 dias do PPP, foram divididas em três grupos homogêneos e dentro de cada grupo subdivididas em dois blocos, um com um PPP < 45 dias (PPP1; n=107) e outro >; 45 dias (PPP2; n=94). Todas as fêmeas receberam um implante auricular contendo 3mg de Norgestomet (Crestar®), seguido pela administração de 5mg de Valerato de Estradiol. Os implantes auriculares foram mantidos durante 10 dias. Na retirada dos implantes, as fêmeas receberam 1mL de solução fisiológica (n=68; Grupo Controle) ou 500UI de eCG (Folligon®; n=67; Grupo eCG) ou 1mg de Benzoato de Estradiol (Index; n=66; Grupo BE) 24 horas após a retirada do implante. A IATF foi realizada 54 horas após a retirada do implante. O diagnóstico de gestação foi realizado por ultra-sonografia 30 dias após a IATF. Houve interação entre os tratamentos e o PPP. No PPP1, a taxa de concepção foi maior no grupo eCG comparado ao BE (47,22% vs. 15,38%; P<0,01). No PPP2, as taxas de concepção dos grupos eCG e BE foram maiores que no grupo controle (41,93%, 44,44% vs. 22,22%; P<0,01). Conclui-se que vacas, com até 45 dias do PPP, o eCG associado ao Norgestomet aumenta as taxas de concepção.

Inglés. This study aimed to compare conception rates at the postpartum period (PPP) in beef cows which were administered either Equine Chorionic Gonadotrophin (eCG) or Estradiol Benzoate (EB) after Norgestomet and submitted to fixed-time artificial insemination (FTAI). The hypothesis was that the administration of eCG or EB enhances the conception rate. Lactating Nelore cows (n=138) and Brangus (n = 63), between 26 and 118 days of post partum period (PPP) were divided into three homogeneous groups, and subdivided in two blocks, inside each group one of them with a PPP d" 45 days (PPP1; n=107) and another with a PPP >; 45 days (PPP2; n=94). All cows received an auricular implant containing 3mg Norgestomet (Crestar®), followed by the administration of 5mg Estradiol Valerate. The auricular implants were kept during 10 days. Cows received 1mL saline solution (n=68, Control Group) or 500IU eCG (Folligon®; n=67; eCG Group) or 1mg Estradiol Benzoate (Index, n=66; EB Group) 24 hours after the removal of the implant. FTAI was made 54 hours after the implant removal. The pregnancy diagnosis was carried through ultrasonography 30 days after FTAI. There was an interaction between treatments and PPP. In the PPP1, the conception rate was higher in the eCG Group than in the EB Group (47.22% vs. 15.38%; Pd"0.01). In the PPP2, the conception rates of the eCG and EB Groups were higher than in the Control Group (41.93%, 44.44% vs. 22.22%: Pd"0.01). It was concluded that in cows up to 45 days of PPP, the eCG associated with Norgestomet enhances the conception rates.