Autor(es)

Consentini, Carlos E. C. ; Carneiro, Tiago O. ; Neri, Humberto ; Batista, Emiliana O. S. ; Silva, Lucas O. e ; Souza, Alexandre H. ; Sartori, Roberto

• Tipo de documento: Artigo Científico
• Fonte: JDS COMMUNICATIONS; v. 3, n. 3, p. 6-pg., 2022-05-01.

Resumo

The present study evaluated the addition of gonadotropin-releasing hormone (GnRH) concomitant or 2 d after the beginning of protocols initiated with estradiol benzoate (EB). A total of 459 multiparous and 371 primiparous lactating Holstein cows were enrolled in the study. Weekly cohorts of cows were randomly assigned to 1 of 3 experimental groups that differed in the strategy to initiate the timed AI (TAI protocol. On d 0, all cows received a 1.55-g progesterone (P4) implant. Additionally, cows in the EBd0 group received 2 mg of EB i.m.; cows in the EBd0-GnRHd0 group were treated simultaneously on d 0 with 2 mg of EB plus 100 mu g of gonadorelin diacetate tetrahydrate (GnRH) i.m.; and cows in the EBd0-GnRHd2 group received 2 mg of EB on d 0 and 100 mu g of GnRH 48 h later (d 2). The remaining treatments in the protocol were similar among groups and included 0.53 mg (i.m.) of cloprostenol sodium (PGF 2 alpha ) on d 7, followed by a second PGF 2 alpha treatment on d 9 (at the time of P4 implant withdrawal) and 1 mg of estradiol cypionate i.m. Then, TAI was performed on d 11 (48 h after P4 removal) in all experimental groups. We detected an effect of treatment on pregnancy per AI (P/AI) on d 30, in which cows from the EBd0-GnRHd2 group demonstrated greater fertility than EBd0 cows, whereas cows in the EBd0-GnRHd0 group did not differ among EBd0 and EBd0-GnRHd0 (40.5 vs. 30.4 vs. 34.4%, respectively). In summary, GnRH treatment at the beginning of an estradiol and P4-based TAI protocol increased fertility only when GnRH was given on d 2. Moreover, a more pronounced positive effect of this strategy was observed in particular classes of cows: multiparous cows, cows with greater milk production, and those receiving the first service. (AU)

• Processo FAPESP: 17/15904-3 - Programas inovadores de pré-sincronização, sincronização e ressincronização para IATF em vacas leiteiras
• Beneficiário: Carlos Eduardo Cardoso Consentini
• Modalidade de apoio: Bolsas no Brasil - Mestrado
• Processo FAPESP: 18/03798-7 - Estudos de fisiologia ovariana e uterina e aprimoramento de Tecnologias de Reprodução Assistida para elevar a eficiência reprodutiva em bovinos
• Beneficiário: Roberto Sartori Filho
• Modalidade de apoio: Auxílio à Pesquisa - Temático