Lambs born from oldest semen

Scientists have successfully impregnated dozens of merino sheep. The sperm used was frozen since 1968. The live birth rate is usually higher only when a semen frozen for less than 12 months is used. This impregnation proves that artificial insemination is safe with frozen semen. The semen was stored in liquid nitrogen at -196 degrees celsius. The sample was collected from a family of sheep farmers who now keep 8000 sheep in Yass plains.