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The pregnancy rate was 61 per cent for the 50-year-old semen against 
59 per cent for a recently frozen sample.

Still swimming after 50 years on ice

Ram sperm frozen in 1968 successfully used to impregnate 34 ewes

Semen stored since 1968 in a laboratory in Sydney, Australia has been defrosted and successfully used to impregnate 34 Merino ewes, with the resulting live birth rate as high as sperm frozen for just 12 months. “This demonstrates the clear viability of long-term frozen storage of semen. The results show that fertility is maintained despite