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

Abstract

The 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.

Fertility response of anestrous buffaloes to eCG2-Modified or Norgestomet plus eCG6- Modified-GnRH-based ovsync protocols during the breeding season.

“…This may be attributed to the persistence of the LF that was present at the time GnRHa1 injection and bypassed its effect and continued to grow at a slower rate due to the negative feedback effect of higher serum P4 level on the frequency and level of the tonic level of LH. Unlike many previous studies whereas eCG was injected at the time of the of Norgestomet ear implant (de Carvalho et al, 2016)or IPVD (P4 releasing intravaginal device)removal (Carvalho et al, 2020),eCG was injected one day before ear implant removal in Norgestomet-eCG6-ovsync in the current study to increase the interval of eCG effect to 3 instead of 2 days before ovulation thereby maximize its growth-promoting action on the LF.…”