Temporal relationships of the LH surge and ovulation to echotexture and power Doppler signals of blood flow in the wall of the preovulatory follicle in heifers
M. A. R. Siddiqui A C , J. C. Ferreira A , E. L. Gastal B , M. A. Beg B , D. A. Cooper A and O. J. Ginther A BA Eutheria Foundation, Cross Plains, WI 53528, USA.
B Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, WI 53706, USA.
C Corresponding author. Email: masiddiqui@wisc.edu
Reproduction, Fertility and Development 22(7) 1110-1117 https://doi.org/10.1071/RD09251
Submitted: 10 October 2009 Accepted: 1 March 2010 Published: 20 August 2010
Abstract
Changes in echotexture and blood flow in the wall of preovulatory follicles in heifers were studied in relation to the LH surge and ovulation in gonadotrophin-releasing hormone-induced (n = 7; Experiment 1) and spontaneous (n = 8; Experiment 2) ovulators. Ultrasonographic examinations and blood sampling were performed either every hour (Experiment 1) or every 6 h (Experiment 2). The interval from LH peak to ovulation in induced and spontaneous ovulators was 27.1 ± 0.3 and 34.5 ± 1.5 h, respectively. Follicle diameter did not increase between the LH peak and ovulation. In the induced ovulators, serration of the stratum granulosum was detected in one (14%), two (29%), three (43%) and four (57%) heifers at 4, 3, 2 and 1 h before ovulation, respectively. An initial increase in blood flow (P < 0.001) encompassed the LH peak in both experiments. In the induced ovulators, blood flow increased (P < 0.02) to maximum 3 h after the LH peak, maintained a plateau for 5 h, decreased (P < 0.05) between 9 and 14 h, increased (P < 0.05) again between 19 and 21 h and then decreased (P < 0.01) between 25 and 26 h (1 h before ovulation). The biphasic increase and decrease in blood flow and serration of the granulosum in the wall of the preovulatory follicle in cattle are novel findings.
Additional keyword: Doppler ultrasonography.
Acknowledgements
This study was supported by the Eutheria Foundation, Cross Plains, WI, USA (Project H1-AZ-07). The authors acknowledge donations of Ovacyst from Phoenix Scientific (St Louis, MO USA) and Lutalyse from Pfizer Animal Health (New York, NY, USA).
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