FACTORS INFLUENCING TO THE RESULT OF EMBR YO-TRANSFER IN CATTLE

The use of embryo transfer (ET) in cattle breeding offers a possibilit y to increase the progeny of genetically valuable high-performance cow s. The present study aimed to find out in how far this goal could be a chieved under the conditions of practical cattle breeding. 3249 cows o f the black and white dairy cattle of the former G.D.R. were analysed. The superovulation rate decreased from 90.1 % to 80.8 % from 1987 to 1989. Furthermore, it was influenced by the breeding plant and the ind ividual donors. The number of intact embryos obtained per donor flushe d is strongly dependent on the given breeding plant, SO-regime (PMSG; FSH) and the mating bull. The pregnancy rate following fresh transfer was most strongly influenced by the breeding plant and the donor withi n the plant. Furthermore, the PMSG procedure was demonstrated to the s lightly superior. The number of calves born from ET per donor cruciall y depended on the number of intact embryos obtained, and on the pregna ncy rate and is most strongly influenced by the level of given breedin g plant. 2.0 calves per donor were born, 1.9 from these were intact an d 0.39 male calves per donor were used for breeding only.