Thoroughbred Breeding: Pedigree Theories and the Science of Genetics

To many followers of Thoroughbred racing, the breeding and pedigree aspect of the business is a difficult to understand science. Casual fans may make use of generalizations or even completely incorrect assumptions, when discussing a horse's breeding and how it may predict his or her aptitude on the track. Many previous books have been written, but they either are too technical and complicated for the casual fan, or are oversimplified, glossing over important concepts that need understood, or even perpetuating those incorrect assumptions. In their latest book, genetics professor Dr. Matthew Binns and racing author Tony Morris set out to right past wrongs, by improving race fan's understanding of Thoroughbred breeding theory.

No study of the Thoroughbred would be complete without looking at the breed's origins and how the present-day horses we see at tracks worldwide descended from the original ancestors, three imported stallions from the Middle East and a set of taproot mares from England. Before even starting any science lessons, the writers spend the first half of the book educating the reader on history. The reader will quickly learn how the stallions got to England, which mares were chosen to be bred to them, which men were instrumental in the beginnings of the breed, and the origins of the General Stud Book.

The direction of the breed was set when the traditional 4-mile heat races for older horses, contested by Eclipse and his contemporaries, were supplanted by much shorter, single-heat events for younger horses, led by the introduction of the Epsom Derby restricted to 3-year-olds over the classic 1 1/2 mile distance. As Federico Tesio famously said, "The Thoroughbred exists because its selection has depended not on experts, technicians, or zoologists, but on a piece of wood: the winning post of the Epsom Derby." Offspring of Eclipse excelled in these races as well as the longer events, and as a result he appears in over 90% of Thoroughbred pedigrees today. The reader also learns about the early research into pedigrees, such as Nicholas Smith's study of inbreeding, Bruce Lowe's numbering of female families by taproot mare, and Joseph Vuillier's study of sires, the forerunner to modern dosage theory.

Having gained an understanding of how the breed got to where it is today, Binns and Morris move on to cover the science. They carefully explain basic concepts such as Mendelian genetics, the role of mitochondrial DNA, the recombination of genes during gamete formation, and the X-factor. The authors use easy-to-understand language aided by diagrams, in order to give the complete novice, including those who are not scientifically minded, just enough knowledge of the concepts to be able to apply these to Thoroughbreds.

With this understanding, it doesn't take long for the reader to see just how inexact "breeding the best to the best" really is. Full siblings only share 25% of genetic material, and the random combining of genes can easily result in two totally different individuals. A study quoted in the book explains that genetics contribute a mere 35% towards racing ability (using Timeform ratings as the standard). This means the other 65% comes from non-genetic influences from environmental variables such as nutrition, trainer, and jockey. This contrasts with coat color, which is completely determined by genetics. As for recent discussions on the weakening of the breed, the authors explain that in the past, breeders did not send mares to stallions with apparent defects, but this is not the case today, where unsound horses are allowed to stand at stud thus propagating unsoundness.

Breeding and genetics play such a key role in Thoroughbred racing that they cannot be ignored. Binns and Morris have produced an excellent work to allow casual fans to gain an understanding of the history and science of Thoroughbred breeding. Although this book is not and was never meant to be used as a handicapping aid, it will help the reader understand how a full sibling to a stakes winner might end up running in claiming company, or the reverse of this, how a horse with parents who were unsuccessful on the track might be competing in graded stakes competition.

Thoroughbred Breeding has a list price of £45.00 (about $70) and can be purchased from Amazon.com for $48.54.

Rating:     4/5

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