Relationships Between Immunoreactive Estrone and Estradiol in Milk, Blood, and Urine of Dairy Cows

Abstract

Quantities of immunoreactive estrone and estradiol in blood plasma, urine, and milk were measured during the estrous cycle and pregnancy of cows. The objectives were to develop a radioimmunoassay procedure for quantifying estrogen in milk and urine and to compare changes in milk estrogen with those in blood plasma and urine. Concentrations of estrone and estradiol in milk varied during the estrous cycle. Relative concentrations of estradiol in blood plasma and milk were not different, but average estrone concentrations in milk were four times greater than those in blood plasma. Concentration of total estrogen (estradiol plus estrone) exceeded 1 ng/ml in colostrum and milk from cows milked prepartum, and was correlated with total estrogen in blood plasma and urine before and after calving. Blood plasma estrone was correlated only with milk estrone whereas blood plasma estradiol was correlated with urinary estradiol, milk estrone, and milk estradiol during the estrous cycle. These results raise possibilities that mammary gland of the lactating cow may concentrate preferentially estrone or convert estradiol to estrone. However, estimated excretion of estrogen through the milk represents no more than a fraction of 1% of the total excreted during the estrous cycle, and the proportion becomes less as gestation progresses up to at least 7 mo.

Hormones, IgG and lactose changes around parturition in plasma, and colostrum or saliva of multiparous sows

“…Our data show a significant correlation between concentrations of E2 in colostrum and those in plasma, especially during parturition. This was also found to be the case in cows [58][59][60]. Österlundh et al [14] reported lower concentrations of E2 in colostrum/milk after parturition (< 100 pg·mL -1 vs. > 500 pg·mL -1 ) than in the present study despite similar concentrations in plasma.…”

The Development of a Sensitive Enzymeimmunoassay for the Determination of Estrone and Estradiol-17.BETA. in Bovine Blood Plasma based on the Same Homologous Combination with Antiserum and Steroid-Enzyme Conjugate

“…The E2β profiles were similar to those in other reports [7,8,12,16,17]. Estrone and E2β showed parallel changes in blood plasma, although E2β was predominant.…”

“…It is obvious that blood plasma E2β is an important indicator of follicular function in cows during the estrous cycle, because those estrogens are mainly derived from follicles [8,12]. On the other hand, pregnant cows during late pregnancy had higher levels of estrogens than those of cycling cows [8,16]. The placenta is the major source of both estrogens [9,10,28] in pregnant cows.…”

Hormones in bovine milk and milk products: A survey

“…They typically average 37.676 pg mL -1 for E2 and 4372 pg mL -1 for E1 in milk, whereas they average 1672 pg mL -1 for E2 and 1071 pg mL -1 for E1 in blood. Monk et al (1975) also determined E2 and E1 contents in milk at three stages of gestation. The authors did not report any increase in estrogens during the cycle, but noticed an increase in plasmatic contents of E2 but not E1, contrary to what has been reported during the ovarian cycle.…”

“…Estrogens concentrations were also estimated using RIA by Monk, Erb, and Mollet (1975) during the gestation and the cycle. Before estrus, the average E2 content was 25.876 pg mL -1 , increasing to 84741 pg mL -1 at estrus and decreasing to 42.4711.2 pg mL -1 after estrus.…”