Use of Doppler ultrasonography in embryo transfer programs: feasibility and field results

Abstract

The intensive use of Doppler ultrasonography in several studies in the last decade allowed the characterization of vascular perfusion and the estimation of function of the reproductive organs and tissues along the estrous cycle and pregnancy in cattle. We aim to discuss the possibility of using Doppler imaging and to explore the potential of its inclusion in reproductive programs in cattle industry. Recent studies in dairy and beef cows indicated a high accuracy and sensitivity when Doppler ultrasonography is used to evaluate corpus luteum function and to diagnosis pregnancy between days 20 and 22. Moreover, resynchronization programs starting 5 to 7 days after timed embryo transfer (FTET) coupled with early pregnancy diagnosis were developed for beef cattle, and have been implemented in commercial embryo transfer programs. These strategies allow a reduction in the interval between two FTET from ≈ 40 to 24 days and may improve the gains in reproductive efficiency when compared to traditional programs than begin resynchronization after the pregnancy diagnosis at 30 days. A second alternative to use Doppler imaging is the evaluation of luteal blood perfusion at the time of embryo transfer for selection of recipients with greater receptivity potential. This may increases fertility in FTET, as embryos would not be transferred to females with non-functional CL, and in cases with recipients surplus, females with higher receptivity would be prioritized.

A novel strategy for resynchronization of ovulation in Nelore cows using injectable progesterone (P4) and P4 releasing devices to perform two timed inseminations within 22 days

“…Therefore, treatments with increased doses of injectable P4 could be preferred as recent studies (Cavalieri, , ) reported that greater doses of P4 might efficiently suppress gonadotropins and induce a new follicle wave. The use of 100 mg short‐acting P4 associated with the P4 device for resynchronization 13–14 days after TAI resulted in pregnancy rates ranged between 45% and 60% cows submitted to fixed‐ET and TAI protocols (Pugliesi et al, ). Our interpretation of the results suggests that administration of 75 mg of long‐acting P4 with insertion of an intravaginal P4 device 12 days after TAI did not significantly affect POF diameter but may improve POF function, as a greater percentage of cows were detected in oestrus and a greater pregnancy rate at the second TAI were observed in cows treated with P4.…”

“…In the control group, cows ( n = 184; 40 primiparous and 144 pluriparous) received a new P4 intravaginal device (Progestar), whereas in the P4‐LA group ( n = 192; 43 primiparous and 149 pluriparous), cows received the P4 device and 75mg P4‐LA (0.5 ml; Sincrogest Injetável, Ourofino, Cravinhos, Brazil). On D20, the devices were removed and cows underwent colour Doppler ultrasonography evaluation to identify non‐pregnant females by structural regression of corpus luteum as previously described (Pugliesi et al, , ). A duplex B‐mode and pulse‐wave colour doppler ultrasound instrument (MyLab Delta; Esaote Healthcare) was used and, cows bearing a CL with >25% of colour signals indicating blood perfusion in the luteal area were considered pregnant on D20 (Pugliesi et al, ).…”

“…Recent studies in dairy (Siqueira et al, ) and beef (Pugliesi et al, ) cattle indicated that colour Doppler ultrasonography could be used as a method for evaluation of corpus luteum (CL) blood perfusion and consequently identify non‐pregnant cattle at 20 days after TAI. The greater accuracy and sensitivity observed for detection of non‐pregnant animals allowed the development of new strategies to reduce the interval between TAI and timed embryo transfer (TEF) to 22–24 days (Baruselli et al, ; Pugliesi et al, ). However, considering that administration of 17β‐oestradiol (E2) esters during the second week of the oestrous cycle may induce CL regression in inseminated dairy cows (Vieira et al, ), the use of increased doses of injectable progesterone (P4) could be an alternative to induce a new follicular wave and avoid the use of E2‐based protocols (Cavalieri, ; Cavalieri, Gaina, & Hepworth, ).…”

>b<Impactos do uso do estradiol na ressincronização superprecoce aos 14 dias pós-IATF em novilhas de corte>/b<

“…Ultrasonography evaluations were performed daily from D14 to D22 for follicular and luteal dynamics ( Figure 1). On D22, an early diagnosis of pregnancy was performed by color-Doppler ultrasonography as previously described in beef cows [9,14]. Heifers with a functional CL (≥ 2 cm 2 and >25% of blood perfusion) on D22 were considered potentially pregnant and had only the intravaginal P4 device removed.…”

“…With the recent advent of innovative methods for early pregnancy diagnosis at 20-22 days using color Doppler ultrasonography [9,10], a novel strategy for resynchronization has rised and a super early resynchronization around 12 to 14 days after the first TAI can be performed [11,12]. The high accuracy (90 to 95%) reported for this method for non-pregnant diagnosis based on identification of the females with luteolysis, allows a reduction in the interval for the second TAI to 22 to 24 days after first TAI [3,[12][13][14]. However, the beginning of this super early resynchronization protocols coincides with a period before the maternal recognition period of gestation (i.e., 15-17 post-estrus days), usually called as the critical period for pregnancy maintenance [15].…”