Science Matters: Cloning Phar Lap
Could Australia's wonder horse be recreated in a laboratory?PT0M0S 620 349
Green Moon's victory in yesterday's $6 million Melbourne Cup came as something of a surprise. Only once in a blue moon, after all, can one be reasonably certain of which horse is likely to win.
One such "wonder horse" was the legendary Phar Lap. Foaled in Timaru, New Zealand, and 17.1 hands tall, Phar Lap triumphed at a time when Australia was at its lowest ebb — the Great Depression of the 1930s.
The chestnut champion, with a multi-generation pedigree, conquered the local racing scene by winning 36 of the 41 races he started — going the distance in 1932 to win North America's richest race, the Agua Caliente Handicap.
The great Phar Lap in action.
Are those days forever over? With his mounted hide at Melbourne Museum, his skeleton at Museum of New Zealand and heart at Canberra's National Museum of Australia, might scientists, given the right bits of Phar Lap's DNA, one day "reconstruct" the former champion?
"The only material you would need to produce a near-identical copy would be some intact cells or, to be precise, the nucleus of the champion horse's cells," says biotechnologist Rajneesh Verma of the Monash Institute of Medical Research.
"The nucleus, which contains DNA, can be transferred to a recipient egg from which the nuclear DNA has been removed – in the same way that Dolly the sheep was created."
Brett Prebble on Green Moon powers away to win the 2012 Melbourne Cup.
A drawback of this approach, Mr Verma says, is that the egg also contains its own mitochondrial DNA – the cell's powerhouse or energy-producing unit — which is present in the resulting clone. "Hence the clone would not be a 100 per cent copy of the champion," he explains.
The key issue here would be that the mitochondria are inherited only from the mother, agrees Sydney University veterinary physiologist Peter Knight.
"Basically what happens is that the mitochondria in the mother's egg get passed on to become the mitochondria in the offspring," Dr Knight explains. "The paternal side does not contribute as the sperm simply contributes DNA and the remaining structures in the sperm, such as the mitochondria, are destroyed after fertilisation."
The Phar Lap display at Victoria's State Museum.
In other words, he says, to recreate Phar Lap scientists would have to use eggs from the horse's mother. "This is because the mitochondria determine the rate at which energy can be produced — and that determines the rate at which energy can be used."
A second and more recent advance in biotechnology is a process for converting any adult cell to make it behave like an embryonic stem cell, obtained from an embryo a few days old. Called induced pluripotent stem cells, in mice they have been able to produce a whole animal.
"While these stem cells have been created for the horse by us and others, it is too early to assume they are identical to such cells from mice," says another Monash biotechnologist, Paul Verma. Also, in their current form, these horse stem cells may not be suitable for generating offspring, as they have been generated using genetic modification.
"If, through research, this can be overcome, such cells would certainly provide a possible way to generate a 100 per cent copy of a champion — at least at the genetic level," Dr Verma says.
The resultant horse, however, is unlikely to be Phar Lap II. "You can have the genes but not be able to reproduce all the other unique variables that make a true champion," Dr Knight says.
It has all to do with the question of nature versus nurture, he explains. A champion racehorse has the capacity to pump vast quantities of blood during exercise. It can do this because it can achieve heart rates of up to 240 beats per minute, its heart pumping more than one litre of blood with each contraction. Horses have the greatest capacity of any animal to use oxygen to supply energy, Dr Knight explains.
To be able to perform like that, everything needs to "right". This includes anything from the horse's physical fitness and freedom from injury to its diet and psychological state.
It's hard to get everything right even when you know what a horse is capable of, Dr Knight says. To predict that in a young horse — racehorses are sold as yearlings at about 18 months old, and do not race until they turn two — is a lottery.
Racing, after all, is a gamble. If canny scientists or trainers could identify yearlings that were likely to be champions, the breeding industry would collapse, Dr Knight says. "So, when we're talking about racing, some ignorance is essential."
It's a mistake to think of champion horses, all of which have good and bad days, as machines, he believes. "Champions have more good days, and the trainer's job is to make sure it stays that way and that good days coincide with big races."
Nature versus nuture
Trying to decide whether nature is more important than nuture is like asking what makes Buddy Franklin a great footballer, or Michael Clarke a great cricketer, Dr Knight suggests.
Nature, he says, begins with the pedigree. "One of the special things about thoroughbreds is that they have been selectively bred for hundreds of years on the basis of their racing ability."
All thoroughbreds are descended from 28 horses. They trace back to three foundation sires – the Darley Arabian, the Byerly Turk and the Godolphin Barb, which date from the early 1700s.
The Darley Arabian's Y chromosome is found in 95 per cent of modern thoroughbred stallions. A mare called Tregonwell's Natural Barb contributed 14 per cent of the genes passed down the female line. On average, any two horses share 47 per cent of their genes. So there is not much genetic variation.
It is possible that having the same sire represented in both the maternal and paternal line has advantages. There are many breeding systems that exploit these so-called "nicks".
But pedigree alone does not tell the whole story. Many expensive yearlings with impressive pedigrees have been unsuccessful racers, and many inexpensive yearlings have had successful careers. The current superstar, Black Caviar, cost $210,000 as a yearling, which is relatively inexpensive in the prestige horse market.
The nurture side begins with the way yearlings are raised. Areas such as New South Wales's Hunter Valley are thought to produce better yearlings because of local conditions. "No one can be sure if this is right or not, but it is true that yearlings raised on pastures deficient in trace minerals may develop skeletal problems as they grow," Dr Knight explains.
Nurture becomes most evident when the horse goes to a trainer. The extent to which the trainer keeps the horse happy depends on close observation and a feeling for the horse's physical and psychological wellbeing.
Human versus horse
The training of horses, which has developed over hundreds of years, is different from that of human athletes, who train far more each week than horses do. Athletes also use vary their training sessions, with periods of harder work followed by easier work. Humans also alternate methods such as training to build fitness and to build strength.
Horses tend to do less work, Dr Knight points out. A typical racehorse will do two gallops a week, over a few hundred metres, with slower work to support the gallop. On non-gallop days, horses will do trotting and cantering work. Horses may stay in work for only a few months before resting for several months or so.
Whether this is the best way to train horses is uncertain. "It seems that general training methods have been optimised," Dr Knight says. "It is possible that a total paradigm shift could result in better results. But this is unlikely to occur, because such shifts are associated with huge risks."
Exercise physiology has been applied by some veterinary scientists, but with limited success. Today, techniques are limited largely to measuring heart rate during exercise, which reveals whether a horse is being worked too hard or too little. Increased heart rate may indicate lameness.
Some trainers in Victoria also measure lactate produced by horses during exercise, which reflects the intensity of the horse's work. By keeping exercise intensity within a zone that produces a certain level of lactate in the blood, usually four to six millimoles per litre, gains in aerobic fitness can be maximised.
Gene tests, that determine which versions of a gene called myostatin are present, provide a good indication of a horse's best distance. On the basis of these tests, horses can be divided into sprinters, middle-distance runners and stayers.
But that does not tell whether horses will be successful at racing. "All a trainer can hope for is to enable an individual horse to perform at its full potential," Dr Knight says. True champions cannot be made, but a horse with great potential can be ruined by poor management and training.
The mental make-up of horses is also important. Some are track-work champions that win few races, and many great racehorses have been track-work bludgers. So much so, Dr Knight explains, that trainers have kept slow horses for them to beat during training gallops — the theory being that you don't want to teach a horse to lose.
As with human champs, horses are champions because they have a winning mindset.
Dr Knight noticed this when conducting exercise-physiology tests. "Horses that got only average physical scores went on to be very good racehorses if they showed the trait of wanting to run," he explains. "Horses that were physically superior, but didn't really want to run, weren't successful."
As the saying goes, you can take a horse to water, but you cannot make it drink. "That's why lobbyists who say racing is cruel are wrong," Dr Knight says. "What they really mean is that they perceive it to be cruel."
Every race, he says, is an opportunity for a horse to show whether or not it wants to race. "If you watched yesterday's Melbourne Cup on TV, you will have noticed horses walking calming around the mounting enclosure, cantering happily off to the barriers, walking around waiting to go into the barriers and then standing quietly waiting for the gates to open. Once they did open, they were keen to race."
Role of jockeys
Fifteen-times British Champion jump jockey Tony McCoy has ridden a record 3368 winners in the course of his career, which is not over yet.
Does this suggest the jockey is as important as the horse?
"Just like any sportsman, jockeys have differing abilities," Dr Knight says. Owners and trainers identify the better jockeys and want them to ride their horses.
"So the best jockeys are usually linked to the best trainers, and thus success feeds on success. Jockeys, or their managers, study form and select the horses they want to ride. In this way, they are just like punters picking the horse they want to back."
This is different from selecting good horses before they race, Dr Knight explains. "Once a horse can race in Melbourne it has already shown racing ability. To jump to Melbourne Saturday races it has demonstrated more ability, and to qualify for a race like the Melbourne Cup they have demonstrated clear superiority."
Does Dr Knight have any tips for this Saturday's race? "You can be certain that it will have a high capacity to deliver oxygen to its muscles and to use that oxygen once it gets there," he says.
It will also have the specific genetic makeup that suits it for racing that distance — as well as the will to win that can only be assessed on the track. "If racing is to continue to fascinate people, then that's the way it has to be," Dr Knight says.
• Watch Green Moon win the Melbourne Cup here.
• Read more about Peter Knight and his research here.
• Check out the work of Rajneesh Verma here.
• Discover more about the world of horse science here.
• Unravel the ins and outs of Phar Lap's history here.
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