The two major functions for horses - recreation and sport - has been helpful for the growth of many breeds, especially in the show ring. Showing has a great influence on breeding and there are two trends developing: the growing uniformity within breeds and the growing uniformity between breeds. We see this in the Appaloosa/Paint/Quarter Horse industry, and in the Warmblood types, for example. This is because many breeders of different breeds are breeding to the same show standard and performance goals. This results in a decline in genetic distinctiveness of many breeds. There are only a handful of truly distinct breeds in North America: the Cleveland Bay is one of them. This gives them the advantage of:
by Linda Yaciw
The Cleveland Bay Horse Society of North America is fortunate to have as an ally Dr. Gus Cothran of the University of Kentucky in the USA. Dr. Cothran is conducting a study of genetic variation in the domestic horse, with particular interest in breeds with small population sizes which include the Cleveland Bay.
In his work with rare breeds, Dr. Cothran provides information to the breed registries that may be of help in developing management plans for genetic conservation with in breeds. As of Dec 31st, 1998, Dr.Cothran has succeeded in bloodtyping 36 Cleveland Bays out of a total population of 54 purebreds in North America.
Blood typing kits are available free-of-charge from the University of Kentucky. The only cost to the CB owner is for blood collection by your own veterinarian and postage to mail the vial to the University of Kentucky. Dr. Cothran provides participants with a copy of the results of the blood typing, and these results may then be forwarded to the Equine Research Station in Newmarket, Suffolk, UK, which is the official agency responsible for keeping DNA/bloodtyping records as required by the Cleveland Bay Horse Society (UK).
At the American Livestock Breeds Conservancy annual meeting at the Kentucky Horse Park, Lexington, Kentucky, USA on June 29, 1996, Dr. Cothran made a presentation about genetic markers and conservation as it relates to all rare breeds. I am quoting some of his general comments that would interest purebred Cleveland Bay breeders.
Among a plethora of other very useful information for the rare breed owner, Dr. Cothran explained how genetic marker analysis in blood typing can "...be used to assess the level and distribution of genetic variation within a rare breed. Such information can be important in developing strategies and assessing the effectiveness of particular management stategies ...Small populations will inevitably lose genetic variation over time due to sampling error in the genes that are passed to each succeeding generation (a process called genetic drift) and the smaller the population, the more rapidly variation is lost. Also, in small, finite populations, every individual in the population will be related to each other, which means inbreeding. Inbreeding also results in the loss of genetic variation. Genetic drift and inbreeding both can lead to reduced genetic variation in rare breeds."
Dr. Cothran explained two ways of looking at genetic variation within a population, as individuals and as the population as a whole. He explained the individual way as "...the proportion of genes in an individual that are variable (the term is heterozygosity). Heterozygosity reflects the degree of inbreeding. The higher the heterozygosity, the lower the inbreeding, and vice versa. As inbreeding can effect (sic) viability and reproductive success, heterozygosity can be considered as a measure of genetic health."
Dr. Cothran explained populational variability as "...a measure of the genetic diversity within a population or breed and is primarily influenced by genetic drift ...Populational variability may be related to the long-term adaptability and viability of a breed and reduced populational variation can lead to reduced individual variation."
Dr. Cothran told of how his blood typing research can help preserve rare breeds, "Genetic marker typing can provide estimates of the levels of both individual and populational genetic variation. If a sufficient number of individuals are examined, the data can be used to develop management strategies for the maximum preservation of genetic variation within a breed."
Another important point of using genetic markers in the preservation of rare breeds is that of parentage testing. According to Dr. Cothran, "Accurate stud books are of critical importance for rare breeds. An incorrect pedigree can lead to inappropriate breeding decisions that could have serious consequences for breeds with very small numbers. For example, it could lead to an increase in inbreeding within the breed. Current techniques using blood group and biochemical genetic marker systems have considerable power for detecting an incorrect parentage..."
When asked how Dr. Cothran got involved in this work, he replied "I came to work with horses through work I was involved with related to genetic management and variation. This is why I am involved with the rare breeds. It allows me to continue the type of studies I am most interested in, rather than just concentrating on the more applied research, which pays the bills." So, if you, reader, are looking for a worthwhile project to donate to, please consider Dr. Cothran's research. Due to its low genetic variance, the Cleveland Bay needs knowledgeable breeders to prevent the breed's extinction. This important knowledge comes to breeders only via dedicated research scientists such as Dr. Cothran.
If an owner wants to breed his purebred mare to Forest Fellow and that mare has already had blood typing done at the University of Kentucky, Dr. Cothran has offered to give me his opinion of whether that particular breeding would be desireable from a genetic point-of-view based on his research.
Thank you Dr. Cothran. I think you and your co-workers will pay a pivotal role in preserving this breed.
For more information contact:
Another Veterinarian who has agreed to help Dr. Cothran by forwarding blood samples to him is Dr. Paul E. Mennick. Dr. Mennick's website is at www.pacintgen.com or e-mail pacintgen@postoffice.worldnet.att.net.
Dr. Mennick and Dr. Donald Peter specialize in worldwide consultation, fertility diagnosis and treatment, breeding services including semen cryopreservation and embryo transfer, USDA-approved import/export quarantine facility, and semi-private training courses.
The purebred Cleveland Bay breeder will be interested in these statements extracted from their website:
USA |
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12 StallionsWheelgate's Lord Charles - California 6 GeldingsStarlane Incognito - Connecticut 6 ColtsIdlehour Yorktown - 1996 - Pennsylvania |
6 MaresLevenmouth Elizabeth - California 18 FilliesAspen - 1996 - Colorado |
Canada |
|
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2 Stallions Forest Fellow - British Columbia |
3 MaresLevenmouth Heatherbelle - Ontario |
"The Cleveland Bay, by its genetic distinctiveness and prepotency, stands in contrast to other Warmblood breeds, which include outstanding individuals but are basically a genetic mix. Such horses are not prepotent because they are not representatives of a true breed, so each individual must be examined for its breeding potential." - a quote from "Ride a Rare Breed" by Carolyn Christman, July 1991, Horsemen's Yankee Pedlar.
http://www.premierpub.com/pursuits/articles/thornton-inbreeding.htm
http://www.premierpub.com/crossroads/xfactor/heart-1.htm
e-mail: lyaciw@pris.bc.ca