RESUMO
On the Slusovice co-operative farm, embryo transfer has been practised since 1984 as a method of controlled reproduction of the heifer and cow herd. The effect of superovulation, embryo recovery and administration of 500 micrograms Oestrophan Spofa upon the donors' conception rate and upon their resuming a new reproduction cycle was studied on this farm. The effect of superovulation, induced by FSH-P (Folicotropin, Spofa), was evaluated in 162 cows, out of which 121 (74.69%) got in calf after three inseminations. Fifty-nine (48.76%) of the pregnant cows got in calf after the first insemination, 38 (31.40%) after the second insemination, and 24 (19.83%) after the third insemination. Having been subjected to embryo collection and luteolysis, the donors conceived within 67.6 days, on an average, and the animals superovulated within 60 days post partum conceived within 59.11 days. The average SP of the superovulated animals was about 148 days but in the donors from which the embryos had been recovered within 60 postpartal days the SP did not exceed 110 days. Hence the earlier postpartal superovulation of cycling cows speeds up the resumption of reproduction in the donors and increases the numbers of recovered embryos. Repeated superovulation had no influence on the fertility of the cows but adequately prolonged the service period.