Skip To Content

NSA and the Ovine Semen Archive

The National Sheep Association and Rare Breeds Survival Trust strongly believes the UK sheep sector needs a gene bank to hold semen and other genetic resources to protect all sheep breeds in the event of a disease outbreak or similar disaster where huge numbers of animals were lost. It is the responsibility of the UK Government to fund this resource, working in partnership with industry to identify and collect appropriate genetic resources and update them regularly.

NSA and RBST is aware some gene banks already exist, but none are representative of the whole UK sheep sector. One example is the Ovine Semen Archive (OSA), which was formed by NSA and RBST in 2009 to manage semen that was originally collected by Defra as part of the National Scrapie Plan (NSP). The semen contained was collected solely in response to the scrapie situation more than 20 years ago and, therefore, the genetics stored are not a true representation of any individual sheep breed. In addition, the store has not been added to at any point since its creation.

However, in lieu of there being a representative and active gene bank, NSA and RBST have agreed to continue to maintain the archive until a suitable replacement can be created. This is in recognition that having some semen in store, albeit not always the most appropriate, is better than having nothing at all. The cost of maintaining the archive is shared by the National Sheep Association and Rare Breeds Survival Trust.

Between November 2020 and August 2022, the contents of OSA were thoroughly reviewed and rationalised. This mainly involved reducing the number of straws per ram to the accepted FAO (Food and Agriculture Organisation) level of 50 straws per ram, but also, where some breeds had straws from more than 25 rams stored, selecting which 25 to retain. In addition, all owners' shares (a hangover from when NSP became OSA in 2009) were removed. This reduced the total size of the store and created a better index of what is in OSA, for when it is called upon as a genetic resource in the future.

A list is available on this page of what is stored within OSA - straws from 873 rams representing 66 different breeds. The rationalisation process means there is very little within the archive that is surplus to requirements. However, where more than 50 straws for a single ram are held, please download a semen release form for details of how to apply for straws to use in your own flock.

For any questions about OSA, please email