Current trends in follow-up of trophoblastic function in ruminant species.

During the pregnancy of ruminants, different hormones and proteins are secreted by placenta or corpus luteum allowing the follow up of gestation. Among them, progesterone (P4) and pregnancy-associated glycoproteins (PAG) were proposed as laboratory tools to establish or to confirm pregnancy diagnosis. In last years, PAG assay also provided useful information for researchers working in programs focused on the follow up of trophoblastic function. Concentrations of PAG appeared as altered after the use of embryo biotechnology (in vitro fertilization, cloning by nuclear transfer, inter-specific pregnancies), according to nutritional status of pregnant females (overnourished or undernourished), or consecutive to infectious diseases leading to pathologies affecting the pregnancy in cows (Actynomyces pyogenes and Neospora caninum) and goats (Toxoplasma gondii, Listeria monocytogenes and Trypanosoma congolense). As well, in numerous studies, the association of repeated ultrasound examinations with P4 and PAG determinations allowed a better understanding of mechanisms related to embryonic and fetal mortalities: failure after artificial insemination or embryo transfer techniques, large offspring syndrome after in vitro fecundation and cloning.