U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska


Date of this Version


Document Type



Published in Beef Research Program Progress Report (1988) No. 3: 80-81


Deep freezing (cryopreservation) of bovine embryos provides an efficient economical method for storing embryos until suitable recipient cows (surrogate mothers) are available, or for transporting embryos to recipient cows at a distant location (e.g., exportation or importation of embryos between continents or geographic areas). Pregnancy rates achieved with frozen bovine embryos have increased steadily during the past five years and are approaching those obtained with fresh bovine embryos. However, acceptable pregnancy rates are only achieved when Grades 1 and 2 quality (excellent and good quality) embryos are frozen; survivability of Grade 3 (fair quality) embryos is considerably higher if the embryos are transferred fresh rather than frozen. A simplified method for freezing and thawing bovine embryos is described, and pregnancy rates obtained are compared with those for fresh embryos.