107 FACTORS THAT INFLUENCE FERTILITY IN AN IVF EMBRYO TRANSFER PROGRAM IN DAIRY HEIFERS

A retrospective study was performed to evaluate factors that influence pregnancy per embryo transfer (P/ET) in an IVF-embryo transfer program. A total of 5026 fresh in vitro-produced embryos were transferred during 2014 and evaluated for effects of embryo quality, embryo stage, size of corpus luteum (CL; 18–19.9 mm or ≥20 mm), interval from GnRH to embryo transfer, number of previous embryo transfer (0, 1, 2, 3, ≥4); and interaction of embryo stage and interval from GnRH to embryo transfer. One group (n = 850) had detection of oestrus after prostaglandin F2α application but most heifers (n = 4176) received fixed timed embryo transfer after a 5-day CIDR-Synch protocol: Day –8 CIDR inserted; Day –3 CIDR removed and prostaglandin F2α; Day –2 prostaglandin F2α; Day 0 GnRH. Ultrasound was performed on Day 6 after GnRH or oestrus to measure CL size and on Day 32 and 60 to determine pregnancy. Data for P/ET were analysed by logistic regression (LOGISTIC procedure, SAS 9.4). Embryo quality influenced P/ET at Day 32 [Grade 1 48.4% (1273/2631) v. Grade 2 37.6% (900/2395); P < 0.01] and at Day 60 [Grade 1 38.9% (1023/2631) v. Grade 2 29.0% (694/2395); P < 0.01], and altered pregnancy loss [Grade 1 19.6% (250/1273) v. Grade 2 22.9% (206/900); P = 0.03]. Stage of the embryo also had an effect on P/ET at Day 32 [Stage 6 35.5%a (582/1641), Stage 7 46.3%b (1431/3092), and Stage 8 54.6%c (160/293); P < 0.01] and at Day 60 [Stage 6 28.2%a (462/1641), Stage 7 36.6%b (1131/3092), and Stage 8 41.6%b (122/293); P < 0.01], but did not affect pregnancy loss (P = 0.22). Interestingly, interval from GnRH (or oestrus) until embryo transfer did not affect P/ET at Day 32 (P = 0.10), 60 (P = 0.23), or pregnancy loss (P = 0.3), nor was there an interaction between interval and embryo stage at Day 32 (P = 0.77), 60 (P = 0.96) or pregnancy loss (P = 0.55). As shown in Table 1, embryo stage 6 was always the lowest and stage 8 always the greatest P/ET regardless of interval from GnRH to embryo transfer. Size of CL also did not affect P/ET at Day 32 (P = 0.09), 60 (P = 0.21), or pregnancy loss (P = 0.90). Number of previous embryo transfer also did not alter P/ET at Day 32 [0 = 43.3% (886/2046), 1 = 44.1% (639/1450), 2 = 43.4% (444/1024), 3 = 42.6% (146/343), and ≥4 = 35.6% (58/163); P = 0.33] or 60 (P = 0.51) or pregnancy loss (P = 0.12). In conclusion, embryo stage and quality are the major factors that impacted P/ET in this study, with surprisingly little effect of interval from GnRH to embryo transfer, size of the CL, and number of previous embryo transfer. Thus, recipient programs for IVF-embryo transfer can be designed with substantial flexibility. Table 1.Effect of embryo stage and recipient synchrony on pregnancies per embryo transfer on Day 32 in recipient dairy heifers

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104 SOFaaci-HEPES or holding media can be used for embryo loading without changes in pregnancies per embryo transfer nor pregnancy loss in an invitro-produced embryo transfer program

Reproduction Fertility and Development ◽

10.1071/rdv32n2ab104 ◽

2020 ◽

Vol 32 (2) ◽

pp. 178

Author(s):

D. Pereira ◽

D. Moreno ◽

R. Sala ◽

L. Carrenho-Sala ◽

M. Fosado ◽

...

Keyword(s):

Embryo Transfer ◽

Fixed Effects ◽

Pregnancy Loss ◽

Embryo Quality ◽

Prostaglandin F2α ◽

P Value ◽

Transfer Program ◽

Embryo Viability ◽

Stage Embryo ◽

Embryo Stage

Time elapsed between removal from culture and embryo transfer (ET) can have a profound effect on the success of an invitro-produced (IVP) ET program. The embryo culture medium provides the necessary nutrients for embryo development and the use of media with a different nutrient composition to load embryos into straws could negatively affect embryo viability. The objective of the present study was to evaluate the effect of type of media used for embryo loading on pregnancy establishment and maintenance. Holstein heifers (n=800) were synchronized using a modified 5-day CO-Synch + controlled internal drug release (CIDR) as follows: Day −8: CIDR inserted, Day −3: CIDR removed, prostaglandin F2α treatment (500μg cloprostenol sodium), Day 0: gonadotrophin-releasing hormone (GnRH; 100μg of gonadorelin acetate). Five days after GnRH, heifers were evaluated by ultrasonography to determine presence of a corpus luteum (CL). Embryos were removed from culture on Day 7 (Day 0=fertilization), placed into tubes containing SOFaaci, and transported in an incubator (LabMix, WTA) to the transfer facility within 1.5h. Upon arrival embryos were removed from transport tubes and randomly assigned to be loaded into 0.25-mL straws containing either holding media (Vigro Holding Plus) or SOFaaci-HEPES. After loading into straws, embryos were placed in an ET gun and AI gun warmers set at 35°C until transfer by 1 of 5 technicians. Heifers with a CL were randomised for transfer of a fresh IVP embryo loaded into a straw containing either holding media or SOFaaci-Hepes on Day 7±1. Interval from embryo loading to transfer ranged from 1 to 3h. Pregnancy was determined by ultrasonography on Days 32 and 60. Data were analysed by logistic regression and included the fixed effects of loading media, embryo stage, embryo quality, interval between GnRH and ET, and biologically relevant interactions. Pregnancies per ET (P/ET) on Day 32 were not different between the groups in which embryos were loaded using holding media and those which used SOFaaci-Hepes, nor there were interactions between loading medium and embryo stage, embryo quality, or interval from GnRH to ET (P>0.10; Table 1). Pregnancies per ET (P/ET) on Day 60 were not different between the loading media groups, nor were there interactions between loading medium, embryo stage, and embryo quality, or interval from GnRH to ET (P>0.10). Pregnancy loss between Days 32 and 60 was not different between groups, nor there were interactions between loading media groups and any other factor (P>0.10). In conclusion, the use of either holding medium or SOFaaci-HEPES for fresh IVP embryo loading does not affect fertility; thus, both are suitable alternatives for loading of embryos into transfer straws. Table 1.Pregnancies per embryo transfer (P/ET) and pregnancy loss in recipient heifers transferred with fresh invitro-produced embryos, using either holding medium or SOFaaci-HEPES medium for loading Item P/ET Day 32 (n) P/ET Day 60 (n) Pregnancy loss (n) Loading medium Holding 47.0% (186/396) 41.3% (163/395) 11.9% (22/185) SOFaaci-HEPES 48.8% (197/404) 43.1% (174/404) 11.7% (23/197) P-value 0.77 0.22 0.84

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110 TREATMENT WITH GnRH ON DAY 5 REDUCES PREGNANCY LOSS IN HEIFERS RECEIVING IN VITRO-PRODUCED EXPANDED BLASTOCYSTS

Reproduction Fertility and Development ◽

10.1071/rdv28n2ab110 ◽

2016 ◽

Vol 28 (2) ◽

pp. 185 ◽

Cited By ~ 2

Author(s):

A. Garcia-Guerra ◽

R. V. Sala ◽

G. M. Baez ◽

M. Fosado ◽

L. F. Melo ◽

...

Keyword(s):

Embryo Transfer ◽

Pregnancy Loss ◽

Body Condition Score ◽

Prostaglandin F2α ◽

Gonadotropin Releasing Hormone ◽

Crown Rump Length ◽

Releasing Hormone ◽

Embryo Size ◽

Embryo Stage

The hypothesis was that GnRH on Day 5 of a synchronized cycle in embryo transfer recipients would increase progesterone (P4) concentrations, embryo size, and fertility. Holstein and cross-bred Holstein heifers (n = 1562) were synchronized using a modified 5-day CIDR Co-Synch as follows: Day –8 CIDR inserted; Day –3 CIDR removed; prostaglandin F2α treatment; Day –2 second prostaglandin F2α; Day 0 gonadotropin-releasing hormone (G1, 100 μg of gonadorelin acetate) to induce ovulation. On Day 5.5, heifers were assigned in a completely randomised design to 1 of 2 treatments: Control (untreated) or GnRH (200 μg of gonadorelin acetate). Transfer of fresh in vitro-produced embryos was performed between d 6 and 8 after G1. Data collected from each heifer included embryo stage and quality, body condition score, technician, interval from G1 to transfer, and number of previous transfers. All heifers were evaluated by transrectal ultrasonography on Day 5, 33, and 62 and a subset of heifers was scanned on Day 12 (n = 718; to determine ovulation to treatment) and another subset on Day 33 (n = 296; 16-s video to determine embryo and amniotic vesicle size). Serum P4 was determined from a subset of heifers on Day 12 (n = 467). Fertility data were analysed by logistic regression (LOGISTIC procedure, SAS 9.4), whereas continuous outcomes were analysed by ANOVA (MIXED procedure). Ovulation to Day 5.5 gonadotropin-releasing hormone was 83.9% (302/360) in GnRH-treated heifers v. 3.3% (12/358) in Control (P < 0.001). Progesterone on Day 12 was greater in GnRH-treated heifers 7.2 ± 0.1 ng mL–1 v. Controls 6.0 ± 0.1 ng mL–1 (P < 0.001). There was an effect of embryo stage at Day 33 and 60 of pregnancy, with Stage 7 having greater P/ET than Stage 6 embryos. Treatment with GnRH did not alter pregnancy per embryo transfer with either embryo stage but decreased pregnancy loss in Stage 7 embryos, as shown in Table 1. Embryo size measured as crown-rump length (CRL) did not differ, as shown in Table 1. Similarly, amniotic vesicle volume (AVV) was not different between GnRH (549.1 ± 16 mm3) and Control (543.5 ± 14 mm3; P = 0.86), nor was there an interaction between treatment and embryo stage (P = 0.71). In addition, neither AVV (P = 0.22) nor CRL (P = 0.41) were associated with pregnancy loss between Day 33 and 60. In conclusion, treatment with GnRH on Day 5 resulted in increased P4 and a reduction in pregnancy loss in heifers receiving a Stage 7 embryo without changing conceptus size. Table 1.Pregnancies per embryo transfer (P/ET), crown-rump length (CRL), and pregnancy loss in embryo recipients receiving gonadotropin-releasing hormone (GnRH) on Day 5.5 v. control

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