This article, Genomics Hits The Farm, over on Forbes, is really sticking in my craw. In it, they describe how mapping the cow genome has made it much more effective in selecting bulls for raising cows that produce higher quantities of milk.
It's similar in theory to the method that we've been using for the last 50 years or so, just a whole lot more accurate. In the year and a half since this new technique was introduced, this genome testing has completely replaced the previous method, which was quite successful in its own right. Over the past three decades, the previous breeding methods had boosted the annual milk production of the Holstein cow (the predominant dairy cow) by 30 gallons, or 8%.
Farmers and genetics companies use testing to select the best bulls for breeding. And, because one selected bull with high-quality semen (producing offspring with higher milk rates) can have lots of offspring, it makes financial sense to breed from a small pool. The end result is that in the U.S. only 500 bulls are bred, using artificial insemination, with 9 million Holstein cows.
On one hand, it's pretty damn amazing that we are able to select for higher production rates, but at what detriment? Much like the chickens that are bred for faster meat production, turkeys that are bred for huge breasts and every other selective breeding that goes on, there are potential problems.
An interesting point that Abbie brought up when I posted this on Facebook was this gem: "According to my uncle, who is a cow endocrinologist, the pregnancy rate is only about 30% from insemination and you're much more likely to get a pregnancy from the natural way. Not to mention that cows have been bred for milk production, not pregnancy rate, so that's part of the problem."
Today, I wanted to bring up the issue of genetic diversity, because when you are working with a narrowing gene pool, problems can arise. I'm sure Greenpa can educate us all on this much better than I (and hopefully will in the comments of this post), but the basic takeaway lesson here is that the smaller gene pool you have, the bigger risk of disease there is, either genetic or acquired.
So, your population of critters (cows in this example) are at higher risk for not surviving or procreating or otherwise serving their purpose if inbreeding a disease comes along or a mutated pathogen infects the whole lot. You see this issue crop up more often in severely depleted populations (like in those species that are endangered), so it's rather tragic to artificially create the same problem in such large populations. The potential for huge die-off may not necessarily be high, but if it does happen, it would be catastrophic.
What do you think? Is it better to selectively breed for highly desired traits at the risk of smaller population diversity? Or is it just better to leave well enough alone and go back to more traditional method of breeding that results in a lower "yield", but leaves more genetic diversity? Or do you even care?