From what we know:
"Larkin-Snowden took swabs from the sheep’s nose and back and front legs, and they were sent to a
laboratory at the University of Warwick which specialises in testing for big cat DNA run by Prof Robin Allaby."
... it was either saliva or hair (but most likely saliva?)
Allaby is a plant geneticist but it seems they offer this DNA service, too.
Edit:
"Many people are convinced of the existence of large cats in the UK of the Panthera, Puma and Lynx genera. The folklore is that these may have been the refugees of the Dangerous Animals Act in 1976, and have found a niche in the UK countryside. In the beginning of 2012, my team was asked to investigate a possible cat kill on National Trust land, and the case received a lot of media attention at the time. This was a very young roe deer carcass. We took swabs and extracted DNA from bite wounds. There was sufficient interest in the subject that I decided to maintain a public support outreach program in which people can send samples they think might have cat DNA for testing.
The test also routinely tests for dogs and foxes, so is appropriate for cases in which the presence of these species may also want to be established. In the case of the big cats above, in fact it turned out that a fox was the more likely guilty party and any putative big cats were innocent on this occasion.
This service costs £100 - it is more than the bats because we test for both felids and canids, and the economies of scale mean we have to charge on a sample by sample basis. The appropriate types of sample should all be in a solid plastic container that can be popped into a jiffy bag in the post. Appropriate sample types are:
- Hair: snagged on a gate for instance.
- Scat: not all of it please, a slither is fine.
- Swab: ideally a sterile medical swab which is basically a cotton wool bud on a stick. Failing that, a cotton wool bud on a stick would do. A few wipes around bite wounds should be sufficient.
On no account send bits of dead body of prey in the post please. We will test for the presence of dogs/foxes and any of the cat species."
https://warwick.ac.uk/fac/sci/lifesci/research/archaeobotany/ecological_forensics/cats/
The cost is an interesting factor as I feel many farmers and ramblers would be deterred by the fee but not a dedicated big cat researcher.
Also looking more saliva as otherwise I feel hair would have been mentioned by the witness.