A pilot project carried out by a team from the Roslin Institute has underscored the value of genotyping in breed conservation work. The project’s aim was to collect genotypes for a number of UK native sheep breeds to investigate genetic diversity and measure genetic parameters, including heterozygosity.

Nasal swabs were collected from twelve native breeds by three students from the Royal (Dick) School of Veterinary Studies from four farms in Scotland between 2021 and 2023. Six of the breeds involved in the study are currently on the RBST Watchlist. The swabs were sent for DNA extraction and genotyping on the Illumina 50K SNP Chip which gave just over 58,000 genetic markers.

Previous studies have found that values of heterozygosi-ty calculated using Single Nucleotide Polymorphism (SNP) arrays in sheep typically range from 0.22 to 0.38, with higher values an indication of genetic diversity within a breed. The values in the breeds analysed for this project all fell within this range, with four rare breeds having the lowest values while the commercial breeds showed the highest. The study also showed that the rare breeds encompass a considerable amount of genetic diversity, having remained genetically distinct from other rare breeds and the production breeds included in the study.

The conclusion taken from the study was that, coupled with normal recording, routine genotyping of rams and the male lamb crop would be a powerful tool for breed conservation. It would help reduce the potential for inbreeding due to small flock sizes and reliance on a small number of rams and should be included in the development of strategies for sustainable conservation of the UK’s native sheep breeds. By applying genotyping to the larger populations of commercial breeds it would also help to ensure the long-term health of the UK sheep industry.

The study was led by Emily Clark with Ellie Kerr, Alissa Scinto, Lauren Collins and Katie Dubarry. The breeds included in the study were Border Leicester, Greyfaced Dartmoor, Lincoln Longwool, Whitefaced Woodland, Lleyn, Poll Dorset, Suffolk, Cheviot, Norfolk Horn, Oxford Down, Wiltshire Horn and Ryeland.

Commenting on the study, RBST Conservation Adviser Andrea Parry-Jones said: “We have previously used genomic analysis in our projects with North Ronaldsay sheep and the British Lop. In the case of the North Ronaldsays, we were able to confirm that the flock on the island of North Ronaldsay has a healthy effective population whilst with the Lop we were able to determine that it can be clearly defined as distinct from other native pig breeds. What this study shows is that genomic characterisation can have a wider role in helping to inform breeding strategies to protect the genetic health of breeds going forward.”