Doctoral student

Improving the cryopreservation of animal semen for artificial insemination purposes

  • School: School of Animal, Rural and Environmental Sciences
  • Starting: 2018
  • Funding: UK student / EU student (non-UK) / International student (non-EU)


This studentship is offered in collaboration with Stallion AI Services Ltd, UK, leaders in the commercialization of stallion semen cryopreservation.  In addition to horses, they are working collaboratively to develop semen cryopreservation techniques in endangered mammals and domestic animal species such as turkeys and camels. Their expertise, combined with cross-school biochemical and physiological expertise from NTU makes for a strong multi-disciplinary supervisory team for a project that has high impact, scientific novelty and industry changing relevance.

Artificial insemination (AI) has been instrumental in supporting genetic improvement and breeding efficiencies in animals, with added biosecurity and welfare benefits associated with animals not meeting.  Though AI fertility rates are highest using fresh or chilled semen, the finite life of sperm limits the scope of use and requires female reproductive monitoring and manipulation that increases costs and welfare issues.  The cryopreservation of semen removes many of these constraints and provides added benefits, including long-term storage, wider transport potential, semen quarantine, natural oestrus mating and gamete banking for competing, genetically superior or dead sires and endangered species.  However, semen cryopreservation is far from established science, even in dairy cattle, the biggest commercial users of the technique, and stallion semen cryopreservation has yet to be developed to a desired level of consistency.

Semen cryopreservation methods and cryoprotectants used in most species are adaptations of those developed for cattle, a non-ideal starting base, and has resulted in some potentially problematic ingredients for some species. Animal-derived additives have improved freezing success for some species, but these have created biosecurity concerns, traceability issues and import restrictions in some countries. Antibiotic use is also falling out of favour due to bacterial resistance risk.  Viable replacements to these additives therefore need to be found.

Equine semen presents a good initial model for the development of cryoprotectants and protocols to improve consistency of success and fertility rates for semen cryopreservation. Utilizing chromatography, mass spectrometry and proteomics, the first main study in this project will: (i) analyze the chemical composition of seminal plasma from several stallions, towards characterization of components with supportive and detrimental effects on sperm survival and (ii) investigate the nature of their supportive actions. Outcomes of this work will inform the second main study of the project to investigate current diluent and cryoprotectant technologies; taking into account impacts of international legislation. The third main study will develop and test novel cryoprotectant formulations and establish their supportive role in maintaining sperm integrity through the freeze and thaw stages, with scope for optimization, leading to commercial trial.  Complementary areas of interest to explore further as part of the project include exploration of how the secretion of beneficial seminal plasma components can be manipulated in vivo and transferring analytical methods and results from the equine study to other species of interest, particularly those with no established cryopreservation methodologies, facilitated by well-established links to these applications via the supervisory team and the industrial partner.

Key outcomes of this project are anticipated to be:

  • A science-led evaluation methodology of in-vivo and in-vitro sperm support and survival during long-term storage and cryopreservation;
  • Development of improved reagents and improved, standardized protocols for species for which cryopreservation is currently used;
  • Transfer of techniques to species where semen cryopreservation is novel with the potential to use the techniques to support food production, sustainability and genetic improvement of food animals of importance to developing nations;
  • Transfer of techniques to endangered species to support managed artificial breeding to preserve genetic diversity, gamete banking, post-mortem harvesting and long-term storage.

A tax-free stipend of circa £14k pa will be awarded to the successful applicant but may be different for international students.  

Shortlisted candidates will be interviewed on 26 July 2018. The closing date is 16 July 2018 and invitations to interviews will sent out by 25 July 2018.  Informal enquiries should be made to

Start Date: 1st October 2018.


Dr Gareth Starbuck

Dr Gareth Cave

Dr Kelly Yarnell

Entry qualifications

Applicants should have a minimum of a 2:1 undergraduate degree or a 2:2 degree and a masters degree in animal science, veterinary science, applied biochemistry or similar relevant subjects. The ideal candidate will also have related experience of working in the animal, veterinary, applied biochemistry, assisted reproduction or similar sector.

How to apply

How to apply

Applications close at 5 pm on Monday 16 July.

Download an application form here.
Please make sure you take a look at our application guidance notes before making your application.

Further information on how to apply can be found on this page.

Fees and funding

The studentship will pay UK/EU tuition fees. It will also provide a maintenance stipend of approximately £14,777 per year for three years (the stipend is linked to the RCUK rate, starting in 2018).

Applications from non-EU students are welcome, but a successful candidate would be responsible for paying the difference between non-EU and UK/EU fees. Fees for 2017/18 are £13,250 for non-EU students and £4,260 for UK/EU students.

Guidance and support

Further information on guidance and support can be found on this page.

Still need help?

Gareth Starbuck