Different times to perform timed artificial insemination when using a P4/E2/eCG-based protocol in buffalo

EnglishThe aim of this study was to evaluate different times for timed artificial insemination (TAI) in buffalo submitted to a P4/E2/eCG-based protocol. In this study, 204 buffaloes were distributed into one of two groups (TAI56, n=103 and TAI64, n=101). At a random stage of the oestrous cycle (Day 0 = D0), in the morning (TAI56, a.m.) or afternoon (TAI64, p.m.), buffaloes received an intravaginal progesterone device (P4; 1.0 g) plus EB (2.0 mg i.m.). On D9 a.m. (TAI56) or p.m. (TAI64), the P4 was removed and buffaloes received PGF2a (0.53 mg i.m. sodium cloprostenol) and eCG (400 IU i.m.). On D10 a.m. (TAI56) or p.m. (TAI64), 24 h after P4 removal, buffaloes were treated with EB (1.0 mg i.m.). Buffaloes from TAI56 and TAI64 were inseminated 56 and 64 h after P4 removal (D11, p.m. and D12, a.m., respectively). Ultrasound examinations were performed on D0 to ascertain ovarian follicular status, at TAI to measure the diameter of the dominant follicle (DF) and D42 for pregnancy diagnosis. The statistical analysis was performed using the GLIMMIX procedure of SAS®. There was no difference between TAI56 and TAI64 for the diameter of the DF at TAI and the pregnancy per TAI. It was concluded that TAI 56 or 64 h after P4 removal did not affect fertility in buffaloes submitted to the induction of ovulation with EB. The present research supports that is possible to perform TAI at any time throughout the day in buffalo synchronized during the non-breeding season portuguesO objetivo deste estudo foi avaliar diferentes momentos para a realizacao da IATF em bufalas submetidas a um protocolo a base de P4/E2/eCG. Neste estudo, 204 bufalas foram distribuidas em um de dois grupos (IATF56, n=103 e IATF64, n=101). Em estagio aleatorio do ciclo estral (Dia 0 = D0), pela manha (IATF56, manha) ou pela tarde (IATF64, tarde), as bufalas receberam um dispositivo intravaginal de progesterona (P4; 1,0 g) e BE (2,0 mg i.m.). No D9 pela manha (IATF56) ou pela tarde (IATF64), a P4 foi removida e as bufalas receberam PGF2a (0,53 mg i.m. cloprostenol sodico) e eCG (400 UI i.m.). No D10 pela manha (IATF56) ou pela tarde (IATF64), 24 h apos a remocao da P4, as bufalas foram tratadas com BE (1,0 mg i.m.). As bufalas dos grupos IATF56 e IATF64 foram inseminadas 56 e 64 h apos a remocao da P4 (D11, pela tarde e D12, pela manha, respectivamente). Avaliacoes ultrassonograficas foram realizadas no D0 para verificar o status folicular ovariano, na IATF para medir o diâmetro do foliculo dominante (FD) e no D42 para o diagnostico de gestacao. A analise estatistica foi realizada utilizando o procedimento GLIMMIX do SAS®. Nao houve diferenca entre os grupos IATF56 e IATF64 no diâmetro do FD na IATF e na prenhez por IATF. Conclui-se que a IATF 56 ou 64 h apos a remocao da P4 nao afeta a fertilidade de bufalas submetidas a inducao da ovulacao com BE. A presente pesquisa evidencia que e possivel realizar a IATF durante todo o dia em bufalas sincronizadas durante a estacao reprodutiva desfavoravel.