On March 31, 2009 the National Survey of Scrapie Genetics in Canadian Purebred Sheep came to a close after three and a half successful years. Also known as the National Genotyping Survey, the project was an initiative that involved a number of Canadian sheep industry groups including the Canadian Sheep Federation (CSF) and the Canadian Sheep Breeders’ Association (CSBA). Industry made a cash contribution of $82,186 to the project, as well as a $107,782 in-kind contribution, meaning time and resources put forth by industry representatives and producers. Government also played a role in the project with funding coming from Agriculture Canada’s Advancing Canadian Agriculture and Agri-Food Program. In total, Ag Canada contributed $436,013 in cash to the project.
Going back to the beginning, the National Genotyping Survey got underway in early summer 2005 when invitation letters were mailed out to over 900 purebred sheep producers nationwide, informing them of the opportunity to get involved with the project. Purebred producers who participated on the project got the chance to genotype test both rams and ewes at a discounted price, receiving a subsidy for each animal tested.
By mid-July of the same year, blood and DNA samples were beginning to be delivered to the participating five laboratories across Canada. As samples were received by the labs, they were tested at codons 136, 154 and 171- the genes associated with how easily sheep can be infected with scrapie once exposed to the disease. By genotype testing, it is possible to determine which animals are genetically resistant to scrapie and will pass that resistance on to their lambs providing producers with valuable information.
Throughout the course of the project, all test results were forwarded to a national database developed by the Nova Scotia Agricultural College (NSAC), in Truro, Nova Scotia. Scrapie Canada worked the NSAC to develop an extension program to interpret genotype results, which helped producers use the genotype information when making breeding decisions.
In total, about 9,300 Canadian purebred sheep were genotype tested through the National Genotyping Survey. Taking into consideration both data sets- national and provincial- the total number of farms and sheep with genotypes in the NSAC database was 18,966 sheep from 496 farms as of March 31, 2009. This is broken down by:
The number of sheep whose genotypes were predicted from the above information is 1,311, making the total number of genotyped sheep in the database 20,277.
The numbers and percentages of Canadian sheep by resistance class are currently:
Industry partnerships and alliances were both developed and strengthened as part of the National Genotyping Survey. The CSBA, the CSF and the NSAC worked closely throughout the project to determine the best method of analyzing and managing the genotyping test results. The industry is now looking at different options for developing a national database.
Through this project, information about genetic testing and scrapie has become more familiar to the Canadian sheep industry, increasing sheep producers’ knowledge of scrapie. Over the course of the project, 50 announcements were made in various national and provincial publications releasing new and up to date information on how to recognize, test for and prevent scrapie outbreaks. A website (www.scrapiecanada.ca) specifically related to scrapie was launched in both English and French and highlighted disease information, as well as information on the National Genotyping Survey.
Overall, the results of the National Genotyping Survey have played, and will continue to play, a positive role in the Canadian sheep industry. The project has furthered the industry’s knowledge of scrapie; it has increased the number of sheep in Canada that have been genotype tested; and it has provided the industry with valuable information to set up scrapie reducing breeding programs. All of these are important steps forward in moving towards a TSE-free industry, as well as keeping Canada in line with scrapie initiatives that are occurring in the international agricultural community.
Scrapie is a fatal disease that affects the central nervous system of sheep and goats. It is classified as a transmissible spongiform encephalopathy (TSE). While the exact cause of scrapie is unknown, it is thought to be associated with the presence of an abnormal protein called a prion.
Clinical signs of scrapie usually don’t become evident for at least a year and a half or sometimes as long as eight years after infection. There is no cure, vaccine or reliable live animal test available for scrapie. Once the clinical signs are observed, the animal will generally die within two months.
Signs of the disease may include: increased aggression or apprehension, disorientation, teeth grinding, biting at limbs and feet, increased scratching, and development of an unusual “bunny hopping” gait.
Scrapie is transmitted at lambing through the placental tissues and fluids of infected ewes. It can be transmitted from a ewe to her lambs and to other sheep and goats which are exposed to the birthing environment.
Variation at three regions of the sheep prion gene (codons 136, 154, 171) are associated with how easily sheep exposed to scrapie will become infected. By genotype testing, it is possible to determine which animals are genetically resistant to scrapie and will pass that resistance on to their lambs. Genotype testing can be completed on blood or DNA samples.
Unique to Canada, this leading edge project provided the knowledge base for increasing resistance of Canadian flocks to scrapie. The survey, which included the sampling of ewes and rams, is currently the most extensive testing program in the world. Because the Canadian project included ewe testing, producers can use the information to develop breeding programs that consider quality and performance as well as scrapie resistance among those top performing animals.
All purebred producers, registering sheep with the Canadian Livestock Records Corporation (CLRC), from across Canada were invited to participate in this initiative.
Other countries, including the USA and Great Britain, are already working to reduce the incidence of scrapie and eventually eradicate it from their flocks. In order to remain competitive and maintain market access, it is in Canada’s best interest to increase resistance to scrapie so that it doesn’t become a trade barrier in the future.
Currently in Canada, flocks which hav been exposed to scrapie may be destroyed. This is a devastating situation for a producer which represents much more than a financial loss. Additionally, this is an animal welfare concern and a cost to the government for compensation programs.
By pro-actively working to increase the resistance of the Canadian flock to scrapie, it will be possible to decrease the negative impacts of this disease
