• Byron Rogers

Genomic Estimated Breeding Values


In our opinion there are two papers on what is wrong with thoroughbred breeding in terms of breed improvement that are really "must reads" for us. The first is a paper written by Burns, et al titled "The Status of Equine Genetic Evaluation" while the second is a great paper written by Dr Betrand Langlois titled "A consideration of the genetic aspects of some current practices in Thoroughbred Horse Breeding".

I have provided links for both of these papers (the fact that one was written back in 1996 says a lot about the industry!) and I would suggest that you download and read them if you have a chance. Both papers outline how much the Thoroughbred Breeding industry is missing in terms of genetic gain by not having industry wide breeding values, or even just having a measure that shows the genetic worth of a horse with a known heritable figure. Right now the industry uses handicap figures (Timeform, Beyer, Ragozin), with no known heritability at all to make its decisions on what genetic merit there is. Timeform aside (Cunningham did a study on their heritability back in the 1970's), using handicap/speed figures to select for breeding/genetic merit is pretty worthless as the stud careers of Formal Gold (peak Beyer of 126) and A.P.Indy (114), show us. And after all, as Langlois postulates "Why should one pay more for this or that pedigree or high performing sire if the performance itself is not heritable?"

There's been a lot of excitement about equine genomic research over the past couple years, but to date it has been a rather one sided affair with horse buyers being able to use products such as Sales Select to better select their yearling and two year old purchases. Breeders however are still waiting for practical performance applications. The good news is that may not be as far away as we think. Dr Anne Ricard, a genetics researcher at the French National Institute for Agricultural Research (INRA) in Joay-en-Josas, France presented to the public in early March (a paper in English is shortly to be published) a first draft of a genomic estimated breeding value model for horses. Inspired by the results of a genomic performance evaluation in dairy cattle, Ricard and colleagues investigated 908 French sport horses, primarily stallions, using a 54,602 code DNA analysis chip (we used a more recent chip with more than 65,000 SNP's). The researchers deigned a complex mathematical formula for developing a reliable performance indicator based on varying levels of coefficients for certain genetic analysis values. They also calculated data from the performance of parents, siblings, and offspring--called "pseudo-performance"--into the formula, weighted according to proximity of the relationship with the horse being evaluated. At this stage, let's call in version 1.0, the model is not yet perfected, but does show promise.

While the research is completed in sport horses, its application to the thoroughbred world is possible. Indeed a properly designed estimated breeding value model, followed by a genomic overlay, would give significant gains to the thoroughbred industry with any measurable trait, not only performance at varying distances, but soundness, and other factors, being modeled.

#Timeform

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