245 Reproductive tract anatomical and physiological assessment by Doppler imaging in alpaca (Vicugna pacos) donors previously superovulated using bovine recombinant FSH (bscrFSH)

The use of Doppler ultrasonography can be interesting for assessing the anatomical status and the physiological process of the reproductive organs with high accuracy and sensitivity while exploring the potential of multiple ovulation embryo transfer (MOET) programs in South American camelids. The main aim was to assess the reproductive tract anatomical and physiological status by Doppler imaging in alpacas (Vicugna pacos) previously superovulated using bovine recombinant FSH (bscrFSH). A total of 30 healthy Suri breed alpacas (age: ∼48 months; bodyweight: ∼60 ± 5 kg; body condition score [BCS; scale 1–5]: 2.5–3.0) located in Melgar province, Peru (Köppen-Geiger: ET; precipitation: ∼600 mm; relative humidity: ∼50%; M.T.: ∼7.9°C, latitude: 14°46′17″S/longitude: 70°54′11″W; altitude: ∼3,970 m.a.s.l.) were previously divided into two groups (n = 15 each) and superovulated using different bscrFSH-derived superovulation (SOV) protocols. The low dose (LD; 100 µg bscrFSH) protocol was applied as follows: Day 0: 0.0082 mg intramuscular (i.m.) gonadotrophin-releasing hormone (GnRH) (a.m.); Day 2, 3, 4, and 5: 40, 30, 20, and 10 μg bscrFSH (i.m.) doses (a.m., total 100 μg), respectively; Day 7: 0.24 mg PGF_2α i.m. dose (a.m.); Day 9: first mating + 0.0082 mg intramuscular GnRH dose (p.m.); Day 10: second mating (a.m.); Day 16: embryo collection. Regarding HD group, the same protocol was applied with slight modifications: Day 0: same; Day 2, 3, 4, and 5: 65, 45, 30, and 15 μg bscrFSH (i.m.) doses (a.m., total 155 μg), respectively; Day 7, 9, 10, and 16: same. Uterine and ovarian-derived structures were scored by Doppler ultrasonography on Day 16: uterine horn diameter (UHD; mm), number of corpora lutea (CL), CL diameter (CLD; mm), CL volume (CLV; mL), non-ovulated follicles (NOF), NOF diameter (NOFD; mm), NOF volume (NOFV; mL). Ovarian blood flow parameters included the resistive index (RI), and pulsatility index (PI). The data matrix was analysed by GLMM (SPSS^® 25, USA). Statistical differences were detected regarding UHD between LD and HD SOV protocols (17.17 ± 0.65 vs 11.24 ± 1.73; P = 0.01). No statistical differences were detected regarding CL (5.46 ± 0.46 vs 5.07 ± 0.56; P > 0.05); however, statistical differences were observed regarding CLD and CLV between protocols (10.77 ± 0.88 vs 7.62 ± 0.42 and 0.95 ± 0.28 vs 0.28 ± 0.22, in LD and HD groups, respectively; P < 0.05). No statistical differences were detected regarding NOF and NOFD between SOV protocols; however, NOFV was statistically higher in LD compared to HD protocol (1.56 ± 0.56 vs 0.70 ± 0.27; P = 0.04). With regard to RI and PI index statistical differences were observed between LD and HD groups (0.49 ± 0.07 vs 0.28 ± 0.06 and 0.86 ± 0.18 vs 0.42 ± 0.10 in LD and HD, respectively; P < 0.05). In conclusion, although both SOV protocols are similar in producing homogeneous number of ovarian structures, differential characteristics in terms of ovarian dimensional and blood flow parameters were observed. These differences may be related to specific bscrFSH concentrations during the SOV protocols. Thus, more adjustments would be necessary to determine the optimal bscrFSH-based SOV protocol for ovarian superstimulation in alpaca (Vicugna pacos) donors.

This research was supported by ANID 21201280.