Genetics Archives - St. Croix Hair Sheep Breeders

Genetics Project Update: Analysis Complete

Posted on October 5, 2023June 3, 2024 by Lori Marion

The SCHSB Directors have worked for over year on a Genetics Project for the breed. We partnered with Dr. Brenda Murdoch at the University of Idaho. She worked to determine if St. Croix sheep can be differentiated from other breeds using genetic testing. Dr. Murdoch further evaluated if both medium-density (60K) and low-density (Flock54) marker panels would generate equally valid results.

The Process

Fifteen (15) SCHSB members from across the country volunteered to obtain tissue samples from their sheep. They selected sheep that represent a variety of bloodlines and phenotypes (shedding, color, muscling, size, fast growth, slow growth, scurs, behavior, eye color, etc.). Several of the sheep express color to varying degrees. It was important to include this variety to ensure that the data collected adequately represents the breed as a whole.

In all, we sent 90 samples to Dr. Murdoch. Of those, 78 were analyzed and some late-arriving samples will be added soon. Dr. Murdoch’s team obtained genotype data from the 78 St. Croix sheep samples using both the 60K and Flock54 marker panels. The team compared our sheeps’ genotypes to those of three other hair breeds (Katahdin, Dorper, Barbados Blackbelly) and several wool breeds (Suffolk, Rambouillet, Targhee, Polypay, Suffolk x Texel, Targhee x Polypay, and wool sheep from the Sheep Discovery Center).

Figure 1 - 60K PCA Plot — *Figure 1 – 60K PCA Plot*

Figure 2 - Flock54 PCA Plot — *Figure 2 – Flock54 PCA Plot*

The Findings

Both the medium-density (60K – see Figure 1) and low-density (Flock54 – see Figure 2) panels produced results that clearly clustered St. Croix sheep (the black dots) in such a way that they can be differentiated from other breeds. Barbados Blackbelly sheep (the dark orange dots) clustered closest, but still exhibit clear separation from the St. Croix sheep in this sample. Dr. Murdoch is confident that both panels can be used to confirm the genetic conformity of a sheep believed to be a St. Croix. There may be some individual Barbados Blackbelly or St. Croix sheep that are so genetically similar that the Flock54 panel may not be adequate without additional statistical analysis.

Next Steps for the Genetics Project

The SCHSB Directors have formed a Genetics Committee to discuss how we will use these findings to meet our central mission; preserving the breed. The committee includes members who participated in the project and expressed an interest in serving. We will consult with experts in genetics and breed conservation.

The Genetics Committee will meet to explore options and make recommendations to the SCHSB Board of Directors. We will consult with the experts throughout the process. The Board will schedule a webinar early in 2024 to help all members fully understand the information.

We encourage members to ask questions and share your thoughts on this matter by contacting us.

St. Croix Genetics Project Update

Posted on June 13, 2023October 1, 2023 by Treasurer Treasurer

by Lori Marion, Vice President

The genetics project is entering its final phase. The last of the tissue samples have been collected, with sheep added from Pennsylvania, Tennessee, and Missouri. The sheep included represent a variety of St. Croix sheep both genetically and geographically from across the United States. Brenda Murdoch, Ph.D., of the University of Idaho Moscow, is finishing with sample analysis and will begin analyzing the full data set shortly.

To get an idea of the depth of Dr. Murdoch’s expertise in sheep genetics, read her article on the genetic structure of terminal breeds in the US. It includes detailed information and while I can’t claim to understand what an ‘eigenvalue’, or a ‘cladogram’ really is, it does give some idea of the complexity of the genetic analysis. If you aren’t overwhelmed by that study, take a look at this one. It details the genetic relationship between Caribbean Hair Sheep and West African sheep breeds.

Thank you to all the SCHSBI members across the country, who donated their time and effort to obtain the samples. We are closer than ever to learning what genetic ‘secrets’ St. Croix sheep may hold and look forward to sharing the findings with our members.