GetBreeding

Wikipedia states: “Lies, damned lies, and statistics” is part of a phrase attributed to Benjamin Disraeli and popularised in the United States by Mark Twain: “There are three kinds of lies: lies, damned lies, and statistics.” The statement refers to the persuasive power of numbers, the use of statistics to bolster weak arguments…

A quick flick through February or March’s horse magazines will show you how statistics are used to bolster arguments. Quite often the statistics are useful, and meaningful. However, looking at the stallion and stud adverts in Horse Deals, and Horse and Hound, I am struck by two things:

1) Not a single stallion advert (as far as I can see) shows reliable/meaningful fertility statistics.

2)Those adverts that do have a “statistic” (if we can call it that), have used a misleading and essentially meaningless number to “bolster” their advert.

For fertility statistics to be meaningful, we need to know how many mares the stallion was bred to, and how many attempts/cycles it took for those mares to become pregnant. Now, these figures are most usefully represented by showing the number of mares (as a perecentage) who became pregnant on the first cycle, or as the average number of cycles it took each mare to become pregnant. Here are some -rough- averages to see what you might expect:

Type of breeding   /    Average first cycle pregnancy rate  /   Average number of cycles for pregnancy

Natural cover or Fresh AI   / 70%   /   1.6 cycles

Chilled semen /  60%  /   2 cycles

Frozen semen  / 40%  /    3 cycles

These are rough averages, and what you might expect of each type of breeding.

I would imagine that if you’ve seen fertility statistics you’ve seen figures like (and I’m quoting these from Horse Deals) “100% in foal success rate” or “99% conception rate” or “high conception rate”. These statistics are not worth the paper they are printed on. Why do I say this? Because these numbers give you no idea of how many mares have been bred to that particular stallion/at that AI centre, and you have no idea how many cycles it took for those mares to become pregnant.

For example… Say the pretend stallion “Mr Dudd” covers 1 mare in 2008 via natural cover. She gets pregnant on the 5th cycle. What figure does the stallion owner quote? “Oh, well 100% of Mr Dudd’s mares went in foal last year” or “Mr Dudd has a 100% conception rate”. If they quoted the statistics properly, it would be an average 1st cycle conception rate of 0 (ZERO) and an average of 5 cycles for the mare to become pregnant. Now obviously, the stallion owner won’t want to quote that (and the number of mares makes the statistic almost totally meaningless (although you would question why it took 5 cycles, right?)), but quoting the “100% conception rate” figure is VERY misleading. The owner could quote:

“100% of mares pregnant within 5 cycles. Of those, each pregnancy required an average of 5 cycles. The overall percentage of cycles resulting in pregnancies was 20%”.

Let’s go for another example… Mr Dudd’s hypothetical sire, “Fye Ring Blanks” is actually quite popular, and covered 20 mares in 2008. 5 mares became pregnant on the first cycle, 5 mares on the 2nd, 5 mares on the 3rd, 2 on the 4th and 3 mares didn’t get in foal at all. Now, old Fye’s owner likes to give the impression that he’s still pretty fertile… so she looks at the numbers. 17/20 in foal… that’s 85% overall. So again, she quotes “85% fertility” which still sounds pretty good. Right? Wrong. His first cycle pregnancy rate is (5/20) 25% which is pretty low.  On average it takes 2.24 cycles to get a mare pregnant, which isn’t so bad. (Don’t forget, all these figures are totally hypothetical, so you’re unlikely to see that combination of numbers). It would be fair for the owner to quote the 2.24 cycles average, but not “85% fertility” because that leads mare owners to believe that they have an 85% chance of their mare being in foal after the first cycle, which is simply not the case. This owner could quote:

“85% of mares pregnant within 4 cycles. Of those, each pregnancy required an average of 2.24 cycles. The overall percentage of cycles resulting in pregnancies was 34%”.

So… the next time you see “100% conception rate”, “99% fertility”, or “all mares in foal in 2008″, have a think about what these statistics are actually saying. Ask the stallion owner or stud what a stallion’s fertility figures were “per cycle” last season. If they can’t give you an answer, they either don’t keep good enough records, don’t understand fertility statistics, or they know the rates are low and don’t want to tell you. Any of these reasons should be cause for concern!

Statistics can be very misleading!

The Metropolitan police are investigating allegations that a senior manager of the UK’s largest NHS Trust used NHS funds to purchase and illegally import equine semen, disguised as human semen for IVF treatment.

Louise Tomkins who runs a stud in Horsham, West Sussex was arrested and questioned last week, after internal NHS audits revealed unusually large purchases of human semen from overseas. It is alleged that Mrs Tomkins had created false invoices to the value of several hundred thousand pounds. However when these invoices were later checked, it appears that the companies the NHS were buying from were actually studs supplying stallion semen.

This incident has not only wasted hundreds of thousands of NHS funds, but could also have posed a huge threat to the UK’s EVA (Equine Viral Arteritis) status. Introducing unauthorised semen into the UK from continental Europe means that the semen could be carrying any number of diseases including CEM, EIA or EVA. If EVA infected semen was inseminated and caused an infection, that infection could spread very quickly causing abortions in mares, and causing stallions to become permanent “shedders” of the virus (in their semen). This kind of EVA epidemic could potentially be disastrous in a country like the UK where EVA is almost non existant, due to much tighter controls than are present in Continental Europe.

Mrs Tomkins, who is the daughter of a former British ambassador to France said the claims were “rubbish”. She said: “There is an ongoing investigation into some invoices that I issued, but it’s got nothing at all to do with horse semen and IVF treatment. That’s all rubbish.” Mrs Tomkins said she was co-operating with the police investigations, but denied all the accusations.

A spokeswoman for the trust declined to comment on the matter, but police confirmed a 45-year-old woman had been arrested and bailed over allegations of fraud at the trust. Hammersmith Hospital is a leading provider of IVF treatment, but felt the need to stress that it does not use horse semen in treatments.

If you think you’ve got a naughty stallion, or have dealt with a nasty one in the past; did he compare to this one?

“…nearly every stallion seems to have a story about how bad he is. While reputations vary, consider the tale that accompanied Executive Officer. A son of the well-known rogue Native Dancer, Executive Officer bit and pawed his handler unconscious. While the man lay on the floor of the breeding shed, the stallion dropped down and rolled on top of him, crushing the man’s pelvis. Then, to add further insult to injury, Executive Officer proclaimed his triumph by urinating on him.”

Taken from The Stallion: A Breeding Guide for Owners and Handlers by James P McCall, PhD. The book can be purchased from Amazon.co.uk by clicking that link.