EN
The aim of these experiments was to attempt equine embryo freezing, using simplified methods. Twelve embryos were frozen, using the vitrification procedure described by Massip et. al. (12), of which 8 were transferred by the non-surgical method. However, none of the recipient mares became pregnant. Using a modified procedure, according to Willadsen (24), 16 embryos were frozen using a simple apparatus for controlling the rate of temperature reduction. The embryos were placed in straws and submersed in ethanol, cooled by a copper spiral, of which one end was immersed in liquid nitrogen. The length, width and volume of the alcohol bath was determined in such a way as to ensure the proper rate of temperature loss (Fig. 1). Of the 8 embryos frozen by this method, 4 were non-surgically transferred, but no pregnancies were obtained. Three of the remaining 4 embryos were surgically transferred through the flank, of which one pregnancy was obtained, being resorbed 40 days after ovulation. One embryo was transferred to the linia alba in England, followed by pregnancy and parturition of a healthy Polish Pony foal.