Friday, April 24, 2009

Playing God With Milk Cows

The Washington Post reports this morning that scientists have managed to sequence the entire genome of an eight-year old Hereford cow living in Montana, the first time a farm animal's entire genome has been published.

Hidden in her roughly 22,000 genes are hints of how natural selection sculpted the bovine body and personality over the past 60 million years, and how man greatly enhanced the job over the past 10,000.

As with other species, genes governing the immune system, the metabolism of nutrients and social interaction appear to be where much of the evolutionary action has occurred. The result is an animal that lives peacefully in herds and grows large on low-quality food, thanks to the billions of bacteria it carries around....

So what? How does a sequenced gene lead to anything positive?

The short answer is that a sequenced gene should enable cattle breeders to create more productive cattle faster because they will be able to find sires with the correct genetic outputs without having to go through the time-wasting (and expensive) process of actually crossing cows and tracking their production over a lifetime.

Traits carried by bulls are important in determining how much milk a cow produces. Because bulls don't make milk, however, a bull's "performance profile" has to be sketched by observing the milk production of his daughters -- a process that takes about six years and costs $25,000 to $50,000. Now, male calves can be tested at birth for milk-enhancing traits using gene-chip technology.
Of course, the great thing about cows and chickens and sheep, is that they actually have a milk, meat, and eggs axis upon which to evaluate the animal.

In the dog world
, a true axis for performance is largely gone. You can find it in the world of racing greyhounds, and (arguably) in the world of working terriers, sled dogs, and border collies. But Chihuahuas and Bulldogs, Scotties and German Shepherds?

Not so much.


retrieverman said...

I just got a comment yesterday defending the breed standard in my breed, saying that people breed "structurally sound" goldens that can still work. "Structurally sound" is a code phrase for "follows the breed standard."

I think showed a bunch of examples of how the show dogs were really poorly designed to do the work.

I can show hundreds of examples, via youtube videos and working retriever commentaries that go back to the early twentieth century.

And still they continue to think that the blond or "white" Newfoundland is the superior type of golden.

I've seen the work. It's a bit like watching a Belgian draft horse try to run the Kentucky Derby.

Most beef cattle aren't bred in registries and arbitrary breed standards. They are bred for the quality of their meat.

Most are outcrossed every few generations. I know lots of "Black Angus" (the marbled meat cattle derived from the Aberdeen-Angus strain) that have Hereford in them. The intermediate strain even has a name. They are called "Black baldies."

HorseCrazedLana said...

Actually, cattle genetics are controlled by some of the larger producers of breeding stock. Bulls' progeny are tracked and measured for traits, whether it be milk production, rib eye area size, birth weight (important for firt time heifers), weaning weight, etc. These are called Expected Progeny Differences, or EPDs. This is a statistic created with a plus or minus for pounds, days, etc. Bulls' data is published and their semen collected and marketed through Select Sires. Producers can find their perfect mates for their cows this way, to match their phenotypes.

HorseCrazedLana said...

Also, that is a picture of a beef, not dairy cow. ;)

HorseCrazedLana said...

Ack, misread, sorry. delete that.

retrieverman said...

Actually, cattle breeding is very much up to the producer. It's not up to the big farmers alone.

I grew up where every farmer had his own bull, and people took pride in their cattle strains.

Crossbreeding is very common in beef cattle production. The most common type is the cross breeding a "Black Angus" (Aberdeen-Angus) bull with a Hereford cow.

The offspring is called a black baldy. It is typically then bred back into the "Black Angus" gene pool until-- I think it's three generations-- it can be registered as full "Black Angus."

In America, we register the Aberdeen-Angus cows in two separate registries. The red ones are in one registry. The black ones are in another. The black ones have been better selected for marbled meat and is better marketed. Today, a black beef that has Angus characteristics is going to earn a higher price at market than virtually any cow.

How do I know this-- well, my grandfather raises beef cattle. He's well-known for raising beefs and Walker-strain American foxhounds. Most of the people I went to school were from families that bred their own strains. Saturdays were spent at the "stock sale," where you could buy new stock to either fatten and sell or add to your strain.