Matthew Binns discusses the genetics of thoroughbred pedigrees

Speaking at the The Blood-Horse-sponsored conference on Thoroughbred Pedigree, Genetics and Performance in Lexington, KY today, Dr. Matthew Binns of The Genetic Edge said that a thoroughbred’s genetics contribute 35-50% toward his athletic ability. 

A founding member of The Equine Genome Project, Dr. Binns’ company performs genetic profiles of thoroughbreds to assess four traits linked to future success on the racetrack, ranking them from A to D.  About 10% of the best bred horses—such as those typically offered on the first day of the Keeneland September sale—are A-rated, with a better-than-average chance of winning in graded stakes.  Dr. Binns noted that it is impossible for even the most experienced horseman to visually identify these genetic markers, which not only tag those horses with the best chances of succeeding in elite company but also unearth their optimal distance and surface preferences and even their eventual height.

Discussing the genetic consequences of inbreeding, Dr. Binns pointed to Zenyatta’s five-cross pedigree, which shows that she is inbred to Champion and Horse of the Year Nashua, 5x5.  What this means, said Binns, is that Zenyatta may have gotten +/-four of her 64 chromosomes—or 6% of her DNA-- from Nashua, but there is also a possibility that she have gotten none of her material from him.  The chances that this inbreeding to Nashua would recreate Nashua’s genotype in Zenyatta are quite low, he said. 

The co-author of Thoroughbred Breeding:  Pedigree Theories and the Science of Genetics, with Tony Morris, Dr. Binns noted that top racemares are the best producers of stakes-class offspring, and also cited evidence that first foals tend to be less successful than subsequent ones because the “placentation” (the facility whereby nutrition is transmitted to an in-utero foal) is not as well developed in maiden mares.  Based on his research on Kentucky Derby winners during the last 40 years, Binns revealed the perhaps surprising fact that a full 50% of them had a genetic profile typical of a sprinter, rather than a router.