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The Sex of A Horse Makes A Difference

This week I am going to look at the fairer sex – no not what some of you might be thinking, but I am talking about the equine fairer sex. You often hear the following comments: “follow a filly in form”, or “back fillies in the autumn”, etc. However, what you don’t often hear is: “fillies and mares are at a disadvantage when racing against their male counterparts”.  This statement however, is TRUE! Looking all types of mixed sex races since 1990, which equates to over 60,000 races, we get the following results:


Colts / Geldings (male)        – strike rate (win %) 9.7%; percentage loss 27%

Fillies/Mares (female)          – strike rate (win %) 7.7%; percentage loss 40%


In other words, males outperform females by an impact value of 1.26. This might not sound too significant, but when you look at their respective percentage losses it is clear that it is very significant. If you randomly backed females rather than males, you would lose an extra £13 per every £100 you bet.


Below is a table showing a variety of circumstances where the gap between males and females increases:




(strike rate)


(strike rate)




Profit / Loss

Female Profit / Loss

Returning to track within 3 days




– 8.8%

– 23.7%

6f to 1 mile races




– 27.6%

– 42.4%

3 year old races




– 24.3%

– 40.9%

Claiming Races




– 31.1%

– 45.1%

Off track for 80 days +




– 32.6%

– 47%

Blinkered for 1st time




– 39.9%

– 56.4%

All weather racing




– 22.9%

– 48.1%


As punters, many of us do not take the “sex” factor into account. We certainly need to, as clearly it is an area where we can gain an “edge” over the majority. I would suggest that next winter, on the all weather, you must take the sex of a horse into account. With males out performing females on the sand by 1.56 times, this is a crucial factor that we cannot ignore!


Moving on to that old adage mentioned earlier: “follow a filly in form”. Unfortunately, you are much better off following a colt or gelding in form. In all open races from 1990, males who had won last time out, won again 17.4% of the time showing a loss of 14%. Females, on the other hand, were able to `repeat` a win 14.9% of the time showing a loss of 26%. The situation did not improve if the horses had won their last two races, so the facts suggest that there is no good reason to “back a filly in form”. The other old adage “back fillies in the autumn” is another fallacy. During the months of September, October and November, fillies and mares win 6.7% of their races for a loss of over 40%. Your best option is to back them in high summer – July and August – at least then you would only lose 33% of your money!


This information about the fairer sex can be used to produce some successful laying systems. Here are just a couple you might like to dabble with in the future:


Laying method 1 – mixed sex races, LAY a filly or mare who is blinkered / visored for the first time when racing on the all weather, and has been off the track for 80 days.


Since 1990 this system would have produced just 2 losing lays from 173 qualifiers for a profit of 160 points (profit of 92.2%). Both winners (losers in our case) were under 10-1.


Laying method 2 – mixed sex races, LAY a filly or mare who is blinkered / visored for the first time when racing on the all weather, and who is running in a claimer.


Since 1990 this system would have produced just 5 losing lays from 279 qualifiers for a profit of 221 points (profit of 79%). Eleven of the sixteen years saw a 100% LAY success rate.

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