225 Evaluation of superovulatory response in Brazilian native sheep by B-mode ultrasonography

Abstract

The objective of this study was to evaluate the correlation between the number of corpora lutea (CL), as determined by B-mode ultrasonography, and the total number of structures recovery by non-surgical embryo recovery (NSER) from superovulated ewes. Somali (n=18), Santa Inês (n=18), and Morada Nova (n=16) ewes received an intravaginal device with progesterone (0.33g, controlled internal drug release device, CIDR, Zoetis), which was maintained for 9 days. The superovulatory protocol started 60h before device removal, with 6 decreasing doses (25, 25, 15, 15, 10, and 10%) of p-FSH (IM 133mg, Folltropin V, Vetoquinol) injected every 12h. D-Cloprostenol (IM 37.5μg, Prolise, Agener Union) was injected 12h before and at the moment of device removal. Ewes in oestrus were mated by fertile male rams three times after the onset of oestrus with a 12-h interval. Flunixin meglumine (24.9 mg; Banamine, MSD Animal Health) was injected IM on Days 12, 13, and 15. One day before NSER, B-mode ultrasound evaluations were performed using portable equipment (Z5 Vet, Mindray) with a stiffened multifrequency linear probe to evaluate the number of structures present in the ovaries. Embryo recovery was performed 7 days after progesterone CIDR removal (Day 16). The number of CL and the number of recovered structures were determined and their association evaluated using the Pearson correlation test (P<0.05). Only 17 Somali, 16 Santa Inês, and 15 Morada Nova ewes were submitted to NSER; the other 4 ewes could not be flushed because of low cervical dilation or cervical puncture. After B-mode ultrasound evaluation, 168, 217, and 131 CL were observed, with an average of 9.9 (range: 1 to 12), 13.5 (range: 2 to 47), and 8.7 (range: 3 to 18) CL per donor for Somali, Santa Inês, and Morada Nova ewes, respectively. The recovery rates (i.e. structures recovered by the number of CL counted) were 60.1% (101/168), 96.3% (209/217), and 103.5% (135/131) for the 3 breeds, respectively. There was a positive correlation (r=0.69; P<0.01) between the number of recovered structures and number of CL. Those findings confirm results from other studies, in which the recovery rate varied from 35 to 91%. In some cases, recovery rate can be overestimated because of the difficulty in quantifying CL. In conclusion, B-mode ultrasonography can be used to estimate superovulatory response in ewes and thus as a criterion to decide whether a donor will undergo embryo flushing. Financial support for this study was provided by Embrapa (02.13.06.026.00.04) and Fapemig (CVZ-PPM 00201-17).