Notice to industry - Advancing eradication: genetic scrapie resistance in goats

April 22, 2021

Testing for genetic resistance in sheep has been a useful tool in scrapie management and eradication. The Canadian goat industry may now also breed for genetic resistance to scrapie. The Canadian goat industry has been supportive of better understanding of genetic resistance in goats to help producers eradicate scrapie.

The Canadian Food Inspection Agency (CFIA) is working towards piloting the use of genetic resistance alleles S146 and K222 (via a pilot study) in the future of our National Scrapie Eradication Program (NSEP). This is an approach consistent with the United States (US) and the European Union (EU).

Research

CFIA-evaluated genotype data collected from several scrapie-infected goat herds in Canada, along with ongoing research findings from North American and European studies, provide convincing evidence for genetic resistance to classical scrapie in goats. Based on the data, goats having a single copy of either the S146 (the amino acid serine at prion protein position 146) or K222 (the amino acid lysine at prion position 222) alleles have shown a strong degree of resistance to natural infection with scrapie.

Over 17 years, the EU studied over 10,000 cases of scrapie in goats. In a 2017 publication, the European Food Safety Authority (EFSA) assembled a panel of experts to evaluate the scientific evidence for scrapie resistance in goats. The panel found the S146 and K222 alleles in goats provided a strong level of resistance to classical scrapie.

Other alleles were also studied by the EFSA, but the data showed resistance to scrapie wasn't as strong. 1 such allele was Q211 (the amino acid glutamine at prion protein position 211). At this time, there isn't enough evidence to support using Q211 for regulatory purposes in our Canadian disease control program; although emerging data continues to be considered.

These 2 alleles (S146 and K222) naturally occur in Canadian goat breeds.

• Allele S146 was most often found in meat breeds such as Boer and Savannah, as well as the Nubian dairy breed.
• The K222 allele has been found less often in the Canadian goats tested up to now, and was mainly found in Toggenburg (dairy) herds.

These alleles will most likely be found in other breeds in Canada as more goats are genotyped.

Internationally, these alleles have been found in the following breeds:

• S146 allele has been found in meat and dairy breeds including Boer, Nubian, Alpine, Saanen and LaMancha.
• The K222 allele appeared most often in dairy breeds such as Toggenburg, LaMancha, Saanen and Alpine.

How this applies to the goat industry

The CFIA, in line with the US, recommends focusing on the S146 and K222 alleles when breeding for resistance in goats. The CFIA is looking to pilot these alleles in our disease response program. This is also in line with a recent 2020 EU regulatory update, which recognized that S146 and K222 offer genetic resistance against classical scrapie. The EU directed incorporating this information into the scrapie disease response, with specifics at the discretion of each Member State.

In Canada, genotyping services for DNA testing of goats at alleles S146 and K222 are available through GoatGEN Inc. and the Animal Health Laboratory.

Producers may use genotyping services for their selective breeding programs and individual herd management decisions. At this time, genotyping results from external laboratories are not considered official, and animals would require testing by the CFIA during a scrapie disease response.

Co-operation and action is required from all parties involved with the health of both sheep and goats. Like scrapie management in sheep, goat producers are encouraged to follow these practices to continue moving Canada towards our goal of scrapie eradication:

• use pre-approved identifiers to identify goats (or place identifiers on them before they leave the farm), until mandatory national identification is in place for this sector.
• increase the submission of mature goats for scrapie sampling
• reduce inbreeding
• select goats bred for genetic resistance for scrapie
• buy goats from herds enrolled on the Scrapie Flock Certification Program (SFCP).

Assessing for scrapie resistance and following the above practices will greatly support Canada's continued progress towards scrapie eradication.

If you have questions or concerns, please contact cfia.ahprograms-programmessa.acia@inspection.gc.ca