[Estrus synchronization in sheep with ICI 80 996].

An experiment was carried out including 96 experimental and 126 control sheep of a herd with the aim to study the synchronizing effect of ICI 80.996 in respect to their sex cycle and to the changes occuring in 17 beta-estradiol and progesteron content and dynamics in the blood plasma at the time of induced oestrus. In the course of three days following the application of the preparation synchronous oestrus was induced in 80.

[Estrus induction in sheep injected with colostrum at different phases of the sexual cycle].

Investigations on the mechanism of colostrum effect in sheep sex apparatus stimulation were carried out. The experiments included 57 sheep, 10 of them used as a check and the remaining 47 distributed in four treatment groups and injected with colostrum at various phases of the sex cycle. It was established that the effectiveness of injecting cow colostrum on sheep with the aim of inducing synchronous oestrus during the regular reproduction season depends on the sex cycle phase at which the injection takes place.

[Relationship between placental weight and the weight of sheep and of lambs at birth].

In 1972--1973 a study was carried out on the sheep flock at the Barley at Institute, Karnobat, to establish the correlation between the weight of placenta and the weight of ewes at impregnation and at giving birth, on the one hand, and the correlation between the weight of placenta and the weight of lambs at birth, on the other hand. The influence of the age of ewes on the weight of placenta was also followed up. Studies were organized with two breed groups of sheep--the newly developed ewe for Southeast Bulgaria, and the Karnobat ewe.

[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.