Enhancing prognostication of corpus luteum function in cows through B-mode and Doppler sonography

Abstract

The utilization of B-mode ultrasound and Doppler techniques in ruminants has emerged as a promising avenue for investigating the intricacies of female reproductive physiology, with a specific focus on the dynamic processes occurring within the follicles and corpus luteum (CL). The primary objective of this investigation was to comprehensively characterize and evaluate the activity of the CL in cows using B-mode and Doppler sonography. To achieve this, 31 Algerian brown atlas cows were subjected to synchronization using the well-established Ovsynch protocol. Ovulation monitoring was conducted using an ultrasound scanner equipped with an endocavitary probe operating at a frequency of 7.5 MHz, precisely 24 and 48 hours after the final administration of GnRH. Subsequently, daily ultrasound assessments were carried out to closely monitor the development of the resulting CL, commencing from the day of ovulation (D0) and continuing up until D20. By meticulously observing morphological changes within the CL, detecting variations in blood flow through ultrasound-Doppler technology, and measuring serum progesterone (P4) levels, three distinct phases were discerned within the comprehensive summary curve, illustrating the relative  evolution of these parameters: a phase characterized by luteal growth, a subsequent static phase, and finally, a regression phase.
Notably, a robust correlation was observed between the area of the CL and P4 (0.67; p < 0.001), as well as between the CL blood flow area and P4 (0.93; p < 0.001). The application of colour Doppler imaging facilitated the estimation of blood flow quantity and patterns within the CL, which indirectly served as an indicator of its functional status. Consequently, assessing the vascularity of the CL holds great promise as a superior marker for evaluating its secretory activity, thereby providing an invaluable tool for making informed reproductive management decisions. These decisions encompass various aspects, including the objective selection of recipients within bovine embryo transfer programs, as well as the timely detection of pregnancies in both heifers and cows.