Abstract
This paper presents the research on the zygotes production, evaluation and transfer in Simmental and Kazakh whitehead cows and heifers, bred in the North-East of Kazakhstan. It was identified that, by applying the German drug «Pluset» in an optimal dose, the average numbers of embryos that can be recovered from the Simmental breed are 8,2 from a cow and 6,4 from a heifer. 66,0 % of embryos from cows were transferable, 17,0 % were non-transferable, 17,0 % of ovicells were unfertilized. Embryos recovered from heifers were identified as transferable 53,1 %, non-transferable 21,9 % and 25,0 % as unfertilized ovicells. The study showed that the embryos recovered from cows and heifers can be found in various stages of development: early morula, compact morula, early blastocyst, blastocyst, hatching and expanded blastocysts. A Kazakh whitehead cow produces 1,3 embryos more than a Simmental cow. The percentage of developed embryos was 45 % in total transplanted embryos. It was determined that the embryos transferred into heifers develop better than embryos transferred into mature cows.