[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 80.2% of the sheep. The percentage of fertilization of the first and second insemination was 44.8 in the experimental group of sheep and 43.2 in the control group, while the percentage of fertility was 101.0 and 73.6, respectively. The rate of the changes occuring in 17 beta-estradiol and progesteron concentration in peripheral blood during the period of ICI 80.996 induced oestrus reveals no deviations from the normal physiological values, typical of that period.