Factors Affecting the Viability of Frozen Stored Cattle Embryos

Abstract

Cattle morulae and blastocysts were frozen, stored in liquid N2 and then warmed and cultured in vitro at 37· 5°C. They were frozen and stored in Dulbecco phosphate buffer enriched with 25 % cattle serum (DB+S)and containing 1·5 M dimethylsulphoxide (DMSO) or 1·0 M glycerol. Embryos were cooled at rates of 0 ·13, 0 ·15 or O· 30°Cjmin and warmed at rates of 1 ·2, 2·2 or 4· 6°C/min (measured over the range 0 to - 50°C). Warming and cooling between 0 and 37· 5°C was at a rate of 0·7°C/min and, after warming, embryos were cultured in DB+S for 12-18 h. A number of embryos were transferred after culture to recipient cows.