Clinical and research applications of real-time ultrasonography in bovine reproduction: a review.

Transrectal real-time ultrasonography has proved to be a rapid and reliable technique for studying reproductive functions in cattle. Through ultrasonography it is now established that follicular growth occurs in wave-like patterns during each estrous cycle. It has been shown that follicular growth and regression continue during early pregnancy, as well as in the postpartum anestrous period. Ultrasound has also helped us to understand the influence of dominant follicles on medium and small follicles. Among the numerous demonstrated applications of ultrasonography, early pregnancy diagnosis, fetal sexing, and postpartum reproductive management appear to be promising areas for immediate application. The new information that has been generated through ultrasound has thrown light on hitherto poorly understood areas of ovarian follicular dynamics, corpus luteum function, pregnancy establishment, and embryonic development in cattle, thereby opening newer areas for research. Still there is great potential for the continued application of this technology to further our understanding of the reproductive processes and to maximize reproductive efficiency of the bovine species. The significant contributions of real-time ultrasonography to the study of bovine reproduction in general and its practical applications in particular are discussed in this paper. The need for taking up technology assessment studies and for the introduction of low-cost portable equipment are stressed. Literature search for this review was done by scanning Current Contents Series 1991-92, AGRICOLA 1980-92, and MEDLINE 1990-92.