EMBRYO-TRANSFER IN EXTENSIVE BEEF BREEDS OF CATTLE

The paper demonstrates success rate of transferring extensive beef bre ed embryos imported from Scotland and Canada to Czech Republic. All im ported embryos were preserved. Freezing, storage, thawing procedures a s well as pre-transfer treatment of embryos respected principles menti oned in Manual of International ET Corporation and veterinary regulati ons. Hereford embryos were transferred to 18 less suitable and superan nuated recipients of a breeder (1st group) and to 14 convenient recipi ents in Research Institute for Cattle Breeding Rapotin (2nd group). Su ccess rate amounted to 16.7% (1st group) and to 75.0% (2nd group, P < 0.05); total conception rate was 37.5% (12/32). Aberdeen-Angus embryos were imported fl om Canada (54.1% conception rate, 20/37) and from Sc otland (43.5% conception rate, 10/23; the conception rate varied in in dividual herds from 20.0% to 61.5%, P < 0.05). Repeated superovulation s of Galloway and Highland donors were successful. Conception rate in recipients of Galloway embryos and Highland embryos amounted to 80.0% (32/40) and to 51.3% (19/37), respectively. Significant differences of conception rates in individual herds (P < 0.05) were found in the two groups. Adequate selection and treatment of heifers - embryo recipien ts - and close collaboration and appropriate informative service betwe en the exporter and workers realizing ET in importing country form the necessary prerequisites of ET success.