In the nick of time

4 min read
Broodmare sire nicks are an often-utilised tool for mare mating assessment. John Boyce tackles the question: how long should you wait before acting on an emerging nicking trend?

The world of nicks between sire and broodmare sire is not always clearly understood.

I recall a breeder asking me to undertake a nicks analysis of a certain sire. The same breeder also noted that I would find a strong affinity between the sire and one particular broodmare sire. My research did indeed show a raised level of success, but when I delved deeper I also noticed that the mares in question were, as a group, simply of a higher standard than all the others.

It was arguable, indeed likely, that the reason for the observed increase in success was down to the quality of mares and not just the broodmare sire.

Crediting a sire-broodmare sire combination with all the success is problematic at best. Many of us will demand a strong statistical basis before employing a nick.

And that means waiting until the results are based on significant sample sizes.


How long do you wait?

But waiting for statistical significance has its costs. For a start, how long do you wait? Wait too long and the nick will become less useful at predicting future success. Not because it becomes less effective, but because your broodmare is now a little older and therefore less likely to produce top-class offspring.

"Wait too long and the nick will become less useful at predicting future success." - John Boyce

Most crosses will never be tried enough to be deemed statistically significant and those that do are probably less useful for the reasons mentioned earlier, plus the fact that breeders tend to ignore good reasons to avoid the cross when there is a good nick involved.

At the end of the day it is all about predicting future success, which is altogether different from observing successful patterns in past results. When we examine past results, there is far more information available to us. We know how good a stallion is and how he does or doesn’t cross with various broodmare sires.

G1 winner Prized Icon is an example of the most successful sire - broodmare sire combination, being by More Than Ready out of a Danehill mare

Of course we can employ as much of this information as we can when deciding the most appropriate stallion for our mare, but most sires that we will be considering for future matings will have no evidence available regarding their own status, never mind about how good the cross is.

Does sample size matter?

Yes, sample sizes do matter, but I would contend that they matter less than the fact that a particular cross has produced one or more good horses, from whatever sample size. From my own research, I have found that two good horses bred on a cross predict more success than one. Five predict more than four, and so on.

"As soon as some compelling evidence presents itself, away you go – as long as you respect all the other requirements of a good mating." - John Boyce

Therefore, as soon as some compelling evidence presents itself, away you go – as long as you respect all the other requirements of a good mating. Waiting two or three more years will only lengthen your odds of success.

Successful sire-broodmare sire combinations in Australia 1990-2018

Our table lists the best sire-broodmare sire combinations for Australian racing since 1990. The leading combination is More Than Ready (USA) with Danehill (USA) mares. It illustrates the point clearly: there are very few young broodmare daughters of Danehill around anymore, so this combination is very much about past glories and less about predicting future success.

Although, there may be clues to future successful combinations descending from these two sires such as More than Ready sons with daughters of sires by Danehill.

It is also true that nicks based on sirelines will produce less significant evidence than those featuring sire and broodmare sire alone. This is simply down to the greater pool of racehorses involved. Quite often sample sizes can run into the thousands or even tens of thousands and therefore end up predicting success at levels nearer the norm for the whole breed.