Abstract
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.
Highlights
timed artificial insemination (TAI) programs are used worldwide to increase reproductive efficiency and to enable genetic improvement in buffalo herds
On day 9, in the morning (TAI56) or afternoon (TAI64), the P4 device was removed and buffaloes received an injection of PGF2a (0.53 mg i.m; sodium cloprostenol; Sincrocio®, Ourofino Agronegócio) plus eCG
The diameter of the dominant follicle (DF) at TAI was similar between treatment groups (TAI56 = 12.9 ± 0.3 and TAI64 = 12.5 ± 0.5; P = 0.45)
Summary
TAI programs are used worldwide to increase reproductive efficiency and to enable genetic improvement in buffalo herds. An optimal pregnancy rate could be achieved when AI is performed 16.2 (MAATJE et al, 1997), 15.3 (AYRES et al, 2008), 14.7 (SÁ FILHO et al, 2013) and 21.8 (SALES et al, 2015) hours before ovulation in cattle. The aim of the present study was to evaluate different times for the performance of TAI in a P4/E2/eCG-based protocol in buffalo submitted to ovulation induction with oestradiol benzoate (EB) 24 h after P4 device removal during the non-breeding season. The hypothesis tested was that TAI performed earlier (56 hours after P4 device removal, ~14 hours before ovulation) would promote an optimal range for spermatic capacitation and viability of the oocyte, and increase the pregnancy rate in a P4/E2/eCGbased protocol in the non-breeding season for buffalo
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