Plasma bovine pregnancy-associated glycoprotein concentrations throughout gestation in relationship to fetal number in the cow

Abstract

This study characterized the peripheral plasma bovine pregnancy-associated glycoprotein (bPAG) profile throughout gestation and examined the effect of stage of gestation and fetal number on this profile in Holstein cows after non-surgical embryo transfer. Cows (n ¼ 12) were divided into three groups: group 1 ¼ normal singleton pregnancies (n ¼ 5); group 2 ¼ normal twin pregnancies (n ¼ 5); group 3 ¼ abnormal twin pregnancies (n ¼ 2). Blood was collected about every third day from day 0 (defined as the first day of standing estrus), then daily for the last 10 days of gestation, and sampling was stopped one day postpartum. The time-related changes in plasma bPAG concentrations were significantly (P < 0:01) affected by the stage of gestation and fetal number (P < 0:01), except during the last 10 days of gestation. In both normal pregnancy groups, bPAG concentration increased rapidly during the first trimester (0.5Ϯ0.1 to 14.6Ϯ1.7 ng/ml and 1.0Ϯ0.6 to 21.8Ϯ4.8 ng/ml, in singleton and twin-bearing groups respectively), then progressively between days 160 and 20 prepartum (31.6Ϯ6.2 to 114.3Ϯ31.3 ng/ml and 41.6Ϯ7.4 to 155.8Ϯ36.6 ng/ml in singleton and twin-bearing cows respectively). The mean concentration between days 20 and 10 prepartum approximately tripled (P < 0:001) in both these groups of cows (114.3Ϯ31.1 to 493.0Ϯ75.3 ng/ml and 155.8Ϯ36.6 to 409.3Ϯ114.7 ng/ml in singleton and twin-bearing cows respectively), but between days 10 prepartum and parturition the values increased about threefold (P < 0:01) in the singleton group (493.0Ϯ75.3 to 1352.8Ϯ286.5 ng/ml) and fivefold (P < 0:001) in the twin-bearing group (409.3Ϯ114.7 to 2154.0Ϯ505.7 ng/ml). The two cows in group 3 that gave birth prematurely to a stillborn calf or to a schistosomus reflexus calf exhibited an aberrant bPAG profile. Our results indicate that peripheral bPAG concentrations are correlated to the stage of gestation and fetal number, and that the profile of the peripheral plasma concentrations provides a useful indication of the feto-placental status.

Expression profile and protein levels of placental products as indirect measures of placental function in in vitro-derived bovine pregnancies

“…This was associated with disturbances in placental development and function, including substrate transfer and accumulation in the uterine compartments , along with differences in the synthetic protein capacity by BCs, as seen in this study, which culminate in the delivery of larger calves (Bertolini et al 2002a). Placental BC products, such as bPL, bPSPB and bPAG-1, have been suggested as useful markers for embryonic or placental health, pregnancy normalcy and embryonic mortality, and for the prediction of abnormal conceptus development and postpartum pathological events (Patel et al 1997, Szenci et al 1998, Tefera et al 2001. Such BC products or the relative abundances of their placental transcripts have already been used in an attempt to detect or predict conceptus abnormalities after in vitro embryo manipulations (Vasquez et al 1995, Schmidt et al 1996, Hill et al 2000, Hashizume et al 2002, Heyman et al 2002, Ishiwata et al 2003, Patel et al 2004a, Ravelich et al 2004, and results from these studies have increasingly contributed to the understanding of those abnormalities.…”

Placental PAGs: gene origins, expression patterns, and use as markers of pregnancy

“…In addition to those described in this review, circulating concentrations of PAGs are also influenced by other factors such as breed, weight, parity status of the dam, fetal sex, fetal number, fetal birth weight as well as the assay platform/antibodies used to perform the PAG measurements themselves (Patel et al 1997, Echternkamp et al 2006, Lobago et al 2009, Mercadante et al 2013. Despite the often perplexing differences observed in circulating PAGs, the measurement of these proteins in maternal blood and milk is becoming a common practice for pregnancy detection in many ruminant production systems.…”

Predicting Embryo Presence and Viability

“…There are many members of the PAG family, and the presence of distinct circulating forms at different stages of gestation may account for the difference in observed half-lives between these studies. In cattle, circulating concentrations of PAGs have been shown to be infl uenced by a number of factors including breed, weight, parity, fetal sex, fetal number, fetal birth weight, and sire of the fetus, along with pregnancy stage and status (Patel et al 1997 ;Lobago et al 2009 ). Overall, PAGs have been shown to be an accurate tool for pregnancy diagnosis in cattle, sheep, goats, buffalo, and elk (Sasser et al 1986 ;Sousa et al 2006 ;Szafranska et al 2006 ;Silva et al 2007 ;Pohler et al 2013 ), and several assay platforms are commercially available for both blood and milk (Leblanc 2013 ).…”