A recent article got me thinking about the scientific approach that has evolved pertaining to the breeding and selection of racehorses, from statistical mining for nicks to biomechanics and cardiovascular analysis. Yet, in spite of the putative science, Thoroughbred racehorses have generally not gotten any faster than their ancestors of 40, 50, or more years ago, with the possible exception of sprints, and have regressed when it comes to endurance. Moreover, contemporary racehorses may not be as durable as their ancestors, using number of career starts as the criterion.
I thought about this seeming lack of progress while reading “Why chickens are twice as big today as they were 60 years ago.” Following are a few excerpts:
- “Chickens we eat today are twice as big as they were 60 years ago. In 1955, the average weight of chickens sold on market was 3.07 pounds, while the number for the first half of 2016 was 6.18 pounds…
- The trend started with the 1948 contest that invited farmers nationwide to develop the “Chicken of Tomorrow” with specific goals — bigger, meatier, faster growth. As a result, Arbor Acre breed, the crossbreed of the two winners, has become the grandparents of most commercial meat chicken we eat today worldwide.
- The time it took to grow a newly-hatched chicken for market has been cut half since the 1990s to only less than 7 weeks from 16 weeks in 1925…And it only takes less than half feed to get the same amount of meat.
- There were massive genetic differences as a result of selective breeding by raising chicken breeds from different eras under exact same conditions, a 2014 study by researchers at the University of Alberta, Canada, observed. The result was stunning: At the same age, the 2005 breed had grown to about four times as heavy as the 1957 breed, despite being fed the same food.”
Why have chickens advanced so dramatically genetically and not racehorses? I am not a geneticist and can’t provide a scientifically-based answer. My layman’s guess is twofold:
First, the quest to breed faster racehorses is impeded by The Jockey Club’s policy that horses cannot be registered unless they are conceived by a registered TB stallion covering a registered TB mare. This precludes genetic engineering and experimental outcrossing with other horse breeds, at least if the owner wants to register the foal.
Second, Thoroughbred racehorses have been selectively bred for speed and endurance for over 300 years (since the days of the breed’s three foundation sires) and may have reached their genetic limits earlier than chickens that began to be selectively bred beginning about 1948.
The fact that racehorses are no faster now than a half century or more in the past matters little in terms of having competitive races. Where genetic engineering and outcrossing for hybrid vigor could possibly help is in breeding more durable and sounder horses less susceptible to breakdowns.
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