295 DOPPLER SONOGRAPHY OF THE OVARIAN ARTERIES IN SUPEROVULATED CATTLE

Abstract

Despite considerable progress in the understanding of ovarian follicular growth in cattle, the variable and unpredictable superovulatory response of donor animals is still a limiting factor to the success in the embryo transfer industry. One of the main factors affecting the outcome is the presence or absence of a dominant follicle at the time of gonadotropin treatment. It has been shown that the removal of the dominant follicle using ultrasound-guided aspiration before superovulation increases the number of ova and transferable embryos (Bungartz and Niemann 1994 J. Reprod. Fertil. 101, 581–593). Transrectal color Doppler sonography has been used to evaluate the blood flow in the ovarian artery and to test the ovarian blood flow in relation to ovarian response upon hormonal treatment for superovulation. It has been determined that blood flow parameters (BFV: blood flow volume, PI: pulsatility index) have only limited diagnostic value to predict the outcome of a superovulation treatment (Honnens et al. 2008 doi.org/10.1016/j.anireprosci.2008.05.077). The objective of the present study was to investigate the effect of dominant follicle ablation on the ovarian blood flow during superovulation related to the outcome. At Day 8 of the estrous cycle, the dominant follicle was removed in 16 animals (Group 1). In 12 animals, the dominant follicle was left intact (Group 2). All animals received an eCG (3000 I.U.) injection on Day 10, a PGF2α injection on Day 12 and were inseminated twice starting 48 h later. Ovarian blood flow was determined in all animals by investigating the left and right ovarian arteries on Days 8, 10 and 12 of the estrous cycle and on Day 6 p.i. using a Logiq Book XP (General Electrics, UK) equipped with a 7.5 MHz probe. Doppler analysis was carried out using Pixelflux software (Chameleon Software, Germany). The PI was measured as described recently (Honnens et al. 2008 doi.org/10.1016/j.anireprosci.2008.05.077). On Day 7 p.i., ova/embryos were collected by standard non-surgical uterine flushing and classified according to the IETS guidelines. Similar results were obtained for the PI in group 1 on Day 8 (1.13 ± 0.08) and Day 10 (1.35 ± 0.09). A decrease (P ≤ 0.05) was measured at Day 12 (0.89 ± 0.07) and Day 6 p.i. (0.60 ± 0.06). In group 2, the PI remained constant until Day 12 (Day 8: 1.34 ± 0.11, Day 10: 1.43 ± 0.14, Day 12: 1.44 ± 0.12). At Day 6 p.i., the PI was significantly reduced (0.66 ± 0.09; P ≤ 0.05). Between both groups, a significant difference (P ≤ 0.05) was only detected at Day 12. More ova/embryos and transferable embryos (P ≤ 0.05) were recovered from group 1 (11.3 ± 1.6, 4.7 ± 0.9) compared to group 2 (4.8 ± 1.2, 1.9 ± 0.6). However, no significant relation (P > 0.05, Spearman) between the PI and the number total ova/embryos or the number of transferable embryos could be determined. These results show that removing the dominant follicle increases the number of embryos after superovulation. However, PI in general could not be used to predict the outcome of a superovulatory treatment.