[17 beta-estradiol and progesterone content of the blood plasma, colostrum, amniotic fluid and placenta of cows].

A study was carried out to shed light on the mode of action and the quantitative interrelationships between the levels of 17 beta-estradiol and progesterone in the blood plasma, colostrum, and amniotic fluid. The idea was to elucidate more fully the question on the role played by colostrum as a stimulant with regard to the polycyclic functions in farm animals. The evaluation of both agents was performed with the aid of KIT (IRC Sorin Torino).

[Lactate dehydrogenase isoenzymes in the colostrum of cows].

Investigated was the isoenzyme spectrum of lactatedehydrogenase in the colostrum of cows which was obtained at various intervals after calving. It was found that the activity of lactate dehydrogenase was most effective immediately following calving when a total of 5 isoenzymes were established, which lowered their activity with the extention of milk secretion.

[Change in the proteins in the colostrum of a cow during the 1st hours after calving].

Studied were the changes taking place in the protein content of the colostrum of cows during the first six hours following calving. The protein fractions were identified by the method of disk polyacrylamide electrophoresis. It was established that the amount of the total protein dropped with the increase in the secretion time.

[Effect of a gestagen used for the induction of synchronous estrus and fertilization of cattle].

The preparations Synchrosyn, Gestafortin, and Bovisynchron, having chlormadinonacetate as a common active ingredient, were used to induce synchronous estrus and fertilization in heifers. A total of 254 animals were involved belonging to the following breeds: Bulgarian Simmental, Bulgarian Red, Bulgarian Brown, and Black Pied. All three preparations were administered orally: Synchrosyn and Gestafortin were given with the forage at the rate of 10 mg chlormadinonacetate, and Bovisynchron was offered twice daily at an interval of 12 hours, rated 1 cu.