Estrogens and progesterone in the posterior vena cava and estrogens in the urine of cattle

TL;DRAbstract

Cannulation of the posterior vena cava of four Jerseys and one Holstein (non-gravid) and one Jersey (gravid) was performed.Blood samples were collected every other day until the tubing plugged* Urine was also sampled at the same time* The samples of blood were analyzed for the estrogens and progesterone and of urine for the estrogens* Two peaks in the total blood estrogens occurred in all cows sampled* In the majority of the cows the first peak occurred during the period of days 6 to 8 and the second during the period of days 12 to 17 after heat* Similarly, the quantities of the excretion of estrogens in the urine reached two peaks* In most of the cows the first occurred during a period between days 3 and 8, whereas the second peak occurred between days 15 to 20, after heat* The levels of progesterone reached a peak level on day.17 Of the estrous cycle* During thirty-four days postconception only one peak of the total estrogens in the blood and urine, corresponding to the first peak ob

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