In Australia, sperm stored in a laboratory in Sydney since 1968 was thawed and successfully used to fertilize 34 merino sheep.
Samples taken from four rams are described as "the oldest known viable sperm in the world." The test results demonstrated the clear viability of long-term stored frozen livestock sperm.
Associate Professor Simon de Graaff of the University of Sydney said: “The lambs appear to have wrinkles on their bodies that were common in Merino in the middle of the last century, designed to maximize the surface area of the skin and coat. According to him, “This Merino style has since lost much of its popularity, since folds have led to difficulties in cutting and increased risk of fly bites.” According to the university, sperm were stored in the form of small granules in large tanks with liquid nitrogen at a temperature minus 196 degrees.
Researchers then conducted in vitro sperm quality tests to determine the motility, speed, viability, and integrity of the DNA of 50-year-old sperm. Original sperm samples were donated in the 1960s from manufacturers belonging to the Walker family. These samples, frozen in 1968 by Dr. Stephen Salamon, were obtained from four rams belonging to the Walkers.