Changes in Plasma Estrogen Concentrations during the First Trimester of Gestation in Dairy Cows: Comparison with the Origin of Embryos and Fetal Number

Abstract

The objectives of this study were to determine the profiles of plasma estrogen concentrations during the first trimester of gestation and to correlate them with the origin of the embryos and fetal number. Pregnancies were induced either by artificial insemination (AI) on the day of estrus (day 0) or by transfer of 1 or 2 blastocysts produced in vitro (IVF-ET) on day 7. Five singleton-bearing cows impregnated by AI, and 6 singleton and 6 twin pregnancies induced by IVF-ET were used in the experiment. Blood was collected by jugular venipuncture at 2 to 5-day intervals until day 100. The concentrations of plasma estrone, estradiol-17β and estrone sulfate were measured by using a radioimmunoassay. Concentrations of all the estrogens fluctuated at low levels until day 50 in all the groups. Thereafter, the concentration of estrone sulfate gradually increased, whereas those of estrone and estradiol-17β remained at basal levels until day 80. The concentration of estrone sulfate after day 50 was affected by the day of gestation and the number of fetuses. After day 80, the concentration of estrone sulfate increased drastically, coinciding with the increases in the estrone and estradiol-17β concentrations. The rate of increase in the concentration of estrone sulfate during days 80 to 100 was the highest among all the estrogens. In the singleton pregnancies, the concentrations of estrone and estrone sulfate between days 80 and 100 were higher in the artificially inseminated cows than in the IVF-ET cows. In the pregnancies induced by IVF-ET, estrone sulfate levels were higher in the twin-bearing cows than in the singleton-bearing cows during days 50 to 80 and 80 to 100. These results suggest that the concentrations of estrogens in bovine peripheral blood plasma could be applied for monitoring fetoplacental development in the first trimester of gestation.Discipline: Animal industry Additional key words: estradiol-17β, estrone, estrone sulfate, in vitro fertilization and multiple pregnancies JARQ 37 (3), 195 -200 (2003) http://www.jircas.affrc.go.jp Present address:

Hormonal and Immunological Changes During Pregnancy Period of Cows

“…Similarly, Opara et al (2006) reported higher level of estradiol in pregnant heifers as compared to estrus or other reproductive conditions (anestrus or diestrus) and in this situation findings of present study are in agreement with these earlier reports. Hirako et al (2003) reported that during the 1 st trimester of gestating cows, E2-17β remained at basal levels until day 80, followed by an increase in estrone and E217β after day 80 of gestation. Also, Al-Anbaky ( 2009) suggested that in pregnant cow's plasma E2 -17β levels varied from 9 pg/ml (in the first third of pregnancy) to 282.60 pg/ml (during the last month of gestation).Similar findings were reported by El-Masry et al…”

“…Several potential mechanisms affect the level of E2-17β during the pregnancy period, whereas the concentration of fetal cortisol from fetal adrenals helps in E2-17β releases from placenta (Gitau et al, 2005). Further, the conversion of testosterone hormone into E2-17β held at the granulosa cells by the action of aromatase (Peters & Ball, 1995;Hirako et al 2003). Also, sex of fetus and the levels of progesterone hormone might also associate with the releases -17β (EL-Fouly et al, 1998 b).…”

“…In addition, high circulating levels of estrogen during pregnancy course (El-Fouly et al, 1998 a;Patel, 1999;Hirako et al, 2003) and glucocorticoids near the onset of parturition can suppress important lymphocyte function (Levkut et al, 2002). Concerning the depression in IgG at postpartum period; Herr et al (2011) revealed that plasma IgG level recovered by the 4 th week of postpartum and the extent of IgG reduction seemed to be depended on the initial IgG concentration.…”