331 Importance of sex-steroids to uterine receptivity for pregnancy in beef cattle.

Abstract In cattle, pregnancy success is mainly determined by the endometrial function from a week prior to conception to three weeks after (i.e., the preimplantation period). The master regulators of endometrial function are the sex-steroids (estradiol and progesterone) and conceptus-derived factors, such as interferon-tau. These factors act in concert to generate a dynamic intraluminal environment that permits optimal development of the conceptus, from early cleavage to elongation, initial apposition and early placentation. In this presentation, data from experimental models that manipulated sex-steroids and from natural occurring variations in these hormones prior to implantation will be reviewed. The use of novel tools such as omics, sensors, artificial intelligence and doppler ultrasonography will be discussed.