ELSENIER Animal Reproduction Science 42 ( 19%) 289-297 REPeoN SCIENCE Mechanisms regulating suckling-mediated anovulation in the cow G.L. Williams a1b9* , O.S. Gazal a, G.A. Guzman Vega a, R.L. Stanko a a Animal Reproduction Laboratory, Texas A&M University Agricultural Research Station, Beeville, 7x, USA b Center for Animal Biotechnology, Institute of Biosciences and Technology, Texas A&M University, College Station, TX, USA Abstract This review summarizes our current understanding of mechanisms through which the suckling calf attenuates gonadotropin secretion and extends the postpartum anovulatory interval of cattle. Recent research has clearly demonstrated the importance of the maternal-offspring bond in mediating these effects, including roles for maternal vision, olfaction, and calf identity. However, little is known about the hormonal and neural control of maternal behavior in cattle. Goals to further define the physiological regulation of this behavior and its relationship to hypothalamic GnRH secretion have recently been facilitated by techniques for monitoring GnRH release in cerebrospinal fluid (CSF) of the third ventricle. Glucose availability, the insulin-likepeptides, and uterine prostaglandin F,, have also been shown to play pivotal roles in the tmnsition out of the anovulatory state. Continuing advances in these areas of fundamental biology should lay the groundwork for the development of novel management strategies of the future. Keywords: Suckling; Anovulation; Cow; Maternal behavior 1. Introduction Suckling-mediated anovulation remains as one of the foremost problems associated with management of beef and dual purpose cattle throughout the world (Short et al., 1990; Williams, 1990). Its importance as a production, management, and research problem is clear if one considers (1) the physiological requirements for maintaining an ?? Corresponding author. Fax: 512/358-4930; e-mail: GLW@tam2OOO.tamu.e&. 0378-4320/%/$15.00 0 1996 Elsevier Science B.V. All rights reserved. PII SO378-4320(96)01531-X