[Level of estrogens in the blood of swine during pregnancy]

Studied were six sows crosses of the White Bulgarian and the Landrace breed during pregnancy for the presence of estrogenic hormones in the blood. The blood was sampled on the 15th, 24th, 34th, 54th, 69th, 89th, 110th, 113th day and on the day following farrowing. It was found that up to the 54th day the level of hormones remains low, not surpassing 2.6 +/- 0.24 ng estron and 2.6 +/- 0.22 ng estradiol per 100 cu. cm plasma. After the 69th day the hormone level rises, and on the day prior to farrowing it reaches up to 286.6 +/- 33.48 ng estron and 8.9 +/- 0.69 ng estradiol in 100 cu. cm plasma. The blood level of hormones was found to drop abruptly reaching almost the same levels that were established at the beginning of pregnancy.