A new record has been set by scientists in Australia after they used the world's oldest known viable semen to impregnate dozens of sheep.
The sperm had been frozen since 1968, but the live birth rate was as high as when using semen frozen for 12 months.
A grand total of 34 lambs were born from the 56 ewes that were inseminated, which is a pregnancy rate of 61 per cent.
The semen had been stored in liquid nitrogen at -196 degrees Celsius.
Dr. Jessica Rickard tested its motility, velocity, viability and DNA integrity and said:
"What is amazing about this result is we found no difference between sperm frozen for 50 years and sperm frozen for a year."
"We believe this is the oldest viable stored semen of any species in the world and definitely the oldest sperm used to produce offspring."