Stallions - Harnesslink

However, no system is perfect and there are a couple of matters that
must be considered when using AEI figures to compare stallions.
Cumulative AEI
The top earner for a stallion can skew the result if they earn a
considerable amount of the total prizemoney. Taking Pentire as an
example, his top earner Xcellent earned approximately $590,000
this season or around 40% of Pentire’s total. Working out Pentire’s
AEI without including Xcellent it comes in at 3.69 – still more than
three times the average of 1.00, but less than his season value of
6.06.To get a result that is less dependent on any one individual, an
AEI for a stallion is best taken over a longer period. In North America
where this system was developed, a cumulative (or lifetime) AEI is
calculated. The advantage of this is that the total pool of money
and runners is larger, so the AEI figure becomes more accurate. Or
put another way, the top-earning individual for a stallion becomes
a smaller percentage of the total money earned. Taking Soviet Star
as an example of seasonal variation, last season he was third on
the AEI list with an AEI of 2.94 – largely due to Starcraft’s earnings
during the Hawke’s Bay carnival. But this season his AEI is only
0.63; less than average. Soviet Star’s AEI for the two seasons
combined is 1.76. This seasonal variation highlights the need for
lifetime figures for a stallion. A lifetime (cumulative) AEI figure evens
out good and bad seasons for the stallion, while still valuing the
dollars earned by the leading money-earner. As discussed above,
because each season is taken as a separate pool, there is no impact
of prizemoney inflation on the lifetime AEI figure.
Mare Quality Opportunity
Another major consideration is the mare quality opportunity that a
stallion receives. The mare brings 50% of the pieces into the genetic
puzzle and that is easily overlooked when assessing the value of
a stallion. So how can we isolate the effect of the mare’s genetic
contribution to establish an accurate measure of the stallion’s
worth? A sire standing at a higher fee often attracts better mares,
while the opposite is true for lesser valued stallions. How can we
quantify the relative quality of the mares served by a stallion, so that
we can objectively assess stallions on a “man-to-man” basis?
Breeders often talk about whether a stallion upgrades his mares or
not. Debate rages about stallions that receive what’s considered
excellent great opportunities with quality mares, and then achieve
a level of moderate success. The debate centres on whether a
Group winner makes such a stallion successful, or whether he’s a
failure for not living up to the quality of mares he served. Conversely,
some stallions leave a decent percentage of good horses, but are
overlooked in the marketplace, perhaps because of small crops,
stud location or various other reasons. How do we easily find out if
a stallion is improving the mares he serves, or if the mares sent to
him are making his results better than they otherwise might be?
Comparable Index (CI)
The Americans overcame the problem of mare quality with the
invention of the Comparable Index (CI). The purpose of the
Comparable Index is to give a value to the quality of mares that
visit a stallion. If a number can be produced that also has 1.00 as
the average value then it can be compared directly to a stallion’s
lifetime AEI. If the AEI is larger than the CI, then the stallion is
an upgrading his mares. For example, Cape Cross is a sire who
has some relevance for New Zealand breeders and has available
figures online (courtesy of USA Bloodhorse magazine). His lifetime
AEI (northern hemisphere) is 1.74, but his CI is 1.35. Hence, Cape
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Cross has improved or upgraded his northern hemisphere mares.
However, if the CI figure is larger than the AEI, then the stallion is
performing worse than the mares sent to him have performed with
other stallions. The key here is to calculate such a figure for the
progeny of the mares sent to a stallion – but using only the progeny
by other stallions. For example, Eight Carat left seven runners by
Zabeel (2), Sticks and Stones, Sir Tristram (2), Gold and Ivory,
Danzatore. To work out her contribution to Zabeel’s CI, you would do
an AEI style calculation for her five runners that were not by Zabeel.
The CI is calculated on the same basis as the AEI – but is more
complicated to compute because the raw data is harder to compile.
The end result, however, is a figure that has the same mechanism
and allows direct comparison between a stallion’s AEI figure and
his CI figure. Simply put, a stallion’s AEI is the performance of his
own progeny, and his CI is the performance of his mares’ progeny
by other stallions.
Mare quality without CI data
However, this information isn’t currently available in New Zealand,
so breeders have to make judgement calls based on more informal
calculations. For example, if a stallion stands at a certain fee level,
say $20,000 or more, then it is assumed he’s had a decent mare
opportunity. But as we don’t have CI figures available, breeders are
forced to assume a level of mare quality. To assist with this, the
American figures are: stallions who stood for $25,000 or more had
an average CI of 2.53; stallions who stood between $10,000 and
$25,000 had an average CI of 1.95; stallions who stood between
$5,000 and $10,000 had an average CI of 1.63; and stallions who
stood for less than $5,000 had an average CI of 0.89.
Figures courtesy of USA Bloodhorse magazine.
Creating AEI/CI for the Asia-Pacific region
With the range of racing conditions and prizemoney available in the
Asia-Pacific region, any system that is going to be used to evaluate a
stallion’s lifetime record needs to be transferable between regions.
Because the calculation of AEI is ratio-based, it copes with the
problem of different average earnings per runner in different regions.
Looking at the American system, they calculate AEI for three regions
– North America, Europe and Japan. These are then combined into
a single figure to produce an overall result for a stallion. The CI
calculation is done on the same basis. It would be ideal for breeders
if these figures could be produced for New Zealand, Australia and
Asia (ie Hong Kong, Singapore etc).
Conclusion
The Average Earnings Index is another tool to help breeders make
decisions. It is particularly useful for sorting out which stallions
throw consistently good offspring and those who are high on the
stallion’s table by sheer weight of progeny numbers. Because the
figures are normalised (ie have an average of 1.00), both the AEI and
CI indexes allow comparisons for a stallion regardless of region. By
using a lifetime figure, this evens out good and bad seasons for a
stallion, giving a more accurate result in the long term. Lifetime AEI
and CI figures for stallions would show the relative merits of each
stallion, and help New Zealand breeders to assess each stallion
fairly. Not only will this show those stallions who have out-performed
their mare opportunity, it will also reveal those stallions who have
succeeded due to a high-quality mare opportunity, yet may not have
lived up to it.
© Renee Geelen & the NZTBA, 2006