What is in this article?:
- To be successful in the milk production business, you have to be able to recognize a good cow.
- These days, farmers use more than their eyes to tell them about a cow’s milk-making potential. They rely on extensive data about her pedigree and the performance of her mother and aunts and sisters. And now the sequencing of the cow genome—completed in 2009 by a team of 300 scientists from 25 countries—has opened a vault of new data and new possibilities.
Excitement over genomic screening
Much of the industry’s excitement about genomic screening has focused on having a new to spot the same traits measured by progeny testing—like a cow’s potential for producing milk, butterfat and protein. But genomics promises a much richer lode of data. Over time, it will make it possible to predict traits that are too difficult or expensive to measure on the thousands of commercial farms that supply data to the progeny testing system, such as genetic predisposition to infertility (see related story), or resistance to disease, or how efficiently a cow converts feed into milk.
“To measure feed intake on an individual animal basis you need a lot of labor and specialized equipment. We couldn’t measure it on hundreds of thousands of animals. It would be prohibitively expensive,” says Weigel. “But you can do it on a few thousand cows in research herds and then DNA-test those animals. If it works as we hope, we’d` be able to take specialized traits and put them in a national breeding program.”
Identifying specialized traits could lead to specialized cows. For example, producers who feed their cattle on pasture might be able to select cows that are really good at converting grass to milk. “In the past all you could do is try to select different sire families whose daughters seem to have done better on grass than on total mixed rations,” says Weigel. “You didn’t really know what you were selecting. But now you could test individual animals and target them for grazing, target them for confinement, target them for producing cheese, or for a certain kind of cheese. ”
“It’s far fetched today,” says Weigel. “But not that far fetched. We can imagine being able to do it.”
Back at the World Dairy Expo show ring, it doesn’t take any data mining to see the cumulative effect that a century of breeding has had on dairy cows. Compared to the squat, rounded cows Ted Halbach’s father judged 70 years earlier, today’s cows are bovine supermodels—longer, taller and svelte. This form has followed function: The industry has selected for cows that put energy into making milk rather than meat.
In recent years, however, it’s become apparent that such cows may not have the resilience to thrive in the larger herds that are becoming the norm in the industry. “This cow has to be able to function in the housing environment. She has to have the physical attributes that sustain and support her production,” explains Halbach. “You can have an animal with great production potential, but if she doesn’t have the physical attributes to reach that potential, she won’t. It’s as simple as that.”
Concerned that cows were becoming too frail, the Purebred Cattle Association asked Halbach in 2007 to lead an effort to revise its unified scorecard—the standard for that hypothetical perfect cow. Halbach turned to research conducted by Weigel, who had analyzed 20 years of data on Holsteins and Jerseys to find links between a cow’s physical characteristics and how long she survived in the herd.
“There was a perception that what makes a good dairy cow was her ability to milk herself—to take all this body tissue, mobilize it, make all this milk from it and not have any extra fat on her,” says Weigel. “Well, she also has to do other things, like get pregnant and not get sick and so on. It became fairly clear that that was a trait where we’ve maybe gone too far.”