299 CONSEQUENCES OF REPEATED ULTRASOUND-GUIDED FOLLICLE ASPIRATION OF THE OVARIES OF GIR (BOS INDICUS) COWS

Abstract

Ultrasound-guided follicle aspiration has been widely used to recover cumulus–oocyte complexes (COC) for in vitro embryo production in cattle, but the safety of this procedure is still under discussion. The aim of this study was to evaluate the negative effects of repeated follicle aspiration on ovarian structure. Pluriparous, non-lactating Gir breed (Bos indicus) cows (n = 22), previously used as COC donors, were evaluated. Follicle aspiration was performed twice a week with a portable ultrasound device, using disposable 19G or 20G needles (Neolus; Terumo Europe, Leuven, Belgium) and a vacuum pressure ranging from 60 to 80 mmHg. At the end of the collection period, cows were examined by rectal palpation and ultrasonography to estimate the degree of ovarian adherence and fibrosis. A group of cows (n = 8) punctured for different periods was selected for histological evaluation of ovarian lesions. Ovaries were surgically recovered 48 h after the last aspiration session, fixed by immersion in a solution of 4% paraformoldehyde and processed for histology. The slides obtained were stained by hematoxylin–eosin and Gomori's trichromic techniques. The association of follicle aspiration and the presence of ovarian abnormalities were estimated by Pearson's correlation method. Results are presented as means ± SEM. The cows evaluated underwent from 9 to 42 puncture sessions, and yielded from 10 to 719 oocytes. Some degree of adherence and/or fibrosis was detected in 37.5% of the ovaries. The incidence of lesions was higher in cows undergoing more than 20 OPU sessions (77.8% vs. 28.6%; P < 0.05). There was a positive correlation between the degree of ovarian adherence and the number of puncture sessions performed (R = 0.31; P < 0.05), but not with the total of oocytes recovered (R = 0.03; P > 0.05). The opposite was observed for ovarian fibrosis, which presented a positive correlation with oocyte yield (R = 0.52; P < 0.05), but not with the number of puncture sessions (R = 0.17; P > 0.05). This difference may be related to the wide range in oocyte yield per donor (means ranging from 1.1 ± 0.9 to 38.6 ± 12.8) and, consequently, in the number of punctures performed in the ovaries. Histological evaluation showed thickening of the tunica albuginea, presence of inflammatory cells infiltration in punctured areas, and increase in the proportion of conjunctive tissue in the ovarian stroma. Punctured follicles showed hemorrhagic clots and variable degrees of disorganization in the follicular wall layers, including dispersion of luteinized cells. These results show that ultrasound-guided follicle aspiration may have negative effects on ovarian structure, depending on the number of sessions performed and oocytes recovered.

This work was sponsored by FAPEMIG and CNPq.