Sex Selection in the Sire


It is not easy to track genes in racehorse families. Occasionally, statistics can indicate that there is sex selection in the sire. The catalogues have started to arrive so how do we use the information to buy a winner? Well, it is a useful document to find most the information in one place. However, a catalogue is unashamedly a selling document and to improve your chance of success you need to know more.  Sometimes the information that is not there is just as important. Both sides of the pedigree require more data. Here is a tip for the male side.

Performance of the Sire

This information can be found in the Australian Stud book or, or a number of similar data bases.  The data shows things like stallion fees, winners/runners, best performers, premiership tables, siblings etc. However, sometimes you have to dig deeper than this. To illustrate the sort of information which could be useful in your investigations let’s look at the stallion performance of Foxwedge (Fastnet Rock-Forest Native).


Foxwedge was an excellent racehorse. In the G1 William Reid he pushed Hay List and Buffering into second and third places.  As a Sire he has a winners/runners ratio of 43.7% which puts him close to horses like So You Think (44.4%) and Nicconi (41.7%). However, what makes his performance worth another look is the fact that his progeny has won three of the highest quality G1 races. Not all G1 races are the same no matter what some industry people say. The table below lists some of the important winners of these races that have been won by his daughters.

All three of Foxwedge’ s G1 winners are fillies. Further investigation shows that of his 18SW, 15 are fillies and 3 are colts. Is there some sort of sex bias operating here? Is it a case of sex selection in the sire? Well, that may be true to a small extent as In the 2013-2015 crops there are 178 fillies and 142 colts.  However, this difference would not explain the SW disparity. It could be chance or is there is a sex-linked factor expressed in the X chromosome of Foxwedge that is related to racing performance. This gene is reinforced by the X chromosome in some of his mares. How do you use this information? If you are interested in Foxwedge progeny, give preference to the fillies. At a service fee of only $11,000 they are definitely worth a look.