The success will bolster hopes that plunging eggs and sperm into the deep freeze is a credible long-term way of providing endangered species with a lifeline
SHEEP semen stored in a lab for over 50 years has successfully impregnated 34 sheep, scientists have revealed.
Samples were taken from four rams back in 1968, and still worked just fine, despite reportedly being the world’s oldest frozen semen.
Australian researchers defrosted the samples, taken by scientists from the University of Sydney.
They inseminated 56 Merino ewes – and 34 became pregnant.
The 61 per cent success rate was higher than that of sperm frozen for only a year - which impregnated 59 per cent of inseminated ewes.
The team said that their research revealed there was “no difference between sperm frozen for 50 years and sperm frozen for a year”.
University of Sydney associate professor Simon de Graaf said: “This demonstrates the clear viability of long-term frozen storage of semen.”
“The results show that fertility is maintained despite 50 years of frozen storage in liquid nitrogen.”
The semen had been stored as pellets in vats of liquid nitrogen below -196C.
The lambs appear to display the body wrinkle that was common in Merinos in the middle of last century, a feature originally selected to maximise skin surface area and wool yields.
This characteristic had been largely bred out of Merinos, because it made shearing harder and increased the chance of fly strike.
Because the new offspring are from old-stock, it will allow the researcher to compare whether the old characteristics were beneficial or not.
The success will bolster hopes that plunging eggs and sperm into the deep freeze is a credible long-term way of providing endangered species with a lifeline.
The original semen samples were donated in the 1960s from sheep owned by the Walker family of Yass Plains.
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