17β-Estradiol and Estrone Concentrations in Plasma and Milk During Bovine Pregnancy

Abstract

Estrone (E1) and 17beta-estradiol (E2) are present in milk, but the mechanism(s) that regulate their appearance in milk are not known. The objectives of this study were to determine the impact of stage of pregnancy on the concentrations of E1 and E2 in plasma and milk and to determine the correlations between plasma and milk E1 and E2 and with milk components throughout pregnancy. Blood and milk samples were collected from 13 cows every 28 d throughout pregnancy. The E1 and E2 were quantified in plasma and milk using RIA after organic solvent extractions and Sephadex LH-20 column chromatography. Plasma E1 concentrations averaged 0.8, 16.9, and 41.8 pg/mL in trimesters 1, 2, and 3, respectively. The respective E1 concentrations in milk averaged 0.6, 7.9, and 27.1 pg/mL. The E2 concentrations in plasma averaged 0.5, 0.9, and 2.0 pg/mL; milk E2 averaged 0.3, 0.9, and 5.0 pg/mL. Plasma and milk E2 concentrations were greater in trimester 3 compared with trimesters 1 and 2. The E1 concentrations in milk were significantly correlated with plasma E1 concentrations (r = 0.77), percentage of milk fat (r = 0.50), and milk yield (r = -0.43). The E2 concentrations in milk were significantly correlated with plasma E2 concentrations (r = 0.93), percentage of milk protein (r = 0.63), and milk yield (r = -0.57). The milk-to-plasma ratio of E2 increased from 0.4 during trimester 1 to 2.2 in trimester 3, which suggested that the mechanism(s) regulating the appearance of E2 in milk may change over the course of pregnancy.

Estrone and Estrone Sulfate Concentrations in Milk and Milk Fractions

“…13,14,19 However, because of the wide discrepancies among reported E 1 values and the limited number of samples analyzed in most studies, there is a need for accurate quantification of E 1 and conjugated E 1 in milk even though E 1 is less biologically potent than E 2 . 20,21 This is especially important considering the growing number of claims that have been made about the health effects of consuming estrone and its conjugates in milk.…”

Qualitative and quantitative comparison of hormone contents between bovine and human colostrums

“…Many studies have analysed bovine milk hormone content (Comin et al, 2005;Farlow, Xu, & Veenstra, 2009;Hatzidakis, Katrakili, & Krambovitis, 1993;Wolford & Argoudelis, 1979) and hormone concentrations during particular physiological stages in the cow, such as the estrous cycle and pregnancy (Foote, Ladd, Lafaunce, Mccauley, & Hasler, 1982;Ginther, Nuti, Garcia, Wentworth, & Tyler, 1976;Ginther, Nuti, Wentworth, & Tyler, 1974;Pape-Zambito, Magliaro, & Kensinger, 2008;Pennington, Spahr, & Lodge, 1981;Rosella, Chiesa, Mattioli, Nannetti, & Giovanna, 1984). However, very few studies have focused on bovine colostrum hormone content, especially cortisol and estrone.…”

Impact of cows’ milk estrogen on cancer risk

“…This effect is probably due to the fact that high feed intake increases liver blood flow and metabolic clearance rate of estradiol by the liver (Sangsritavong, Combs, Sartori, Armentano, & Wiltbank, 2002). Pape-Zambito et al (2008) estimate that the majority of cows producing milk for consumption would have less than 2 pg mL À1 of estradiol. This estimate is based on their studies with herd milk and milk from pregnant cows and because early lactation cows have high milk yields and farmers generally dry off cows at 60 days before the next expected calving.…”

“…In addition, during the past 60e70 years milk production per cow has increased about 5-fold due to improved genetics for milk production coupled with changes in nutritional management (Capper, Cady, & Bauman, 2009). Estradiol concentrations are negatively correlated with milk yield (Pape-Zambito et al, 2008). This effect is probably due to the fact that high feed intake increases liver blood flow and metabolic clearance rate of estradiol by the liver (Sangsritavong, Combs, Sartori, Armentano, & Wiltbank, 2002).…”