Finding a cow's inner dairynessFinding a cow's inner dairyness
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.
February 17, 2011
The cardinal rule in dairy judging is that, if you’re in doubt, you pick the cow with the best udder. Few people know that better than Brian Coyne, who grew up on a dairy farm near Eau Claire and began judging cows when he was 10. Yet in the biggest contest of his life, he was about to throw that maxim out the window.
Coyne, a CALS senior majoring in dairy science, was getting his first look at a group of Milking Shorthorns—four of the 48 cows he evaluated during the National Intercollegiate Dairy Judging Contest at the 2010 World Dairy Expo—and the first one in line really caught his eye. He liked every part of her, save one: She clearly had the worst udder of the group.
“She was huge,” Coyne recalled later. “She was really clean-cut. She had a big, sharp front end on her.” Despite her mammary shortcomings, she had what Coyne looks for in a great cow: “She was really dairy.”
“Dairy” is a compliment paid often around venues like the World Dairy Expo. You hear it from judges at the event’s seven major breed shows, from onlookers at the big-money cattle sales held each night, and from the visitors who stream through the barns that house nearly 2,500 of the world’s best show cows. The term is a bit of industry shorthand, usually uttered in awestruck tones to explain what separates an outstanding cow from one that’s merely good: “She is just so dairy!”
To be successful in the milk production business, you have to be able to recognize a good cow. Dairy judging contests teach one of the oldest ways of doing that: giving her a good long look, from muzzle to hip bones and rump to hooves, to see how closely she conforms to “true type,” the hypothetical perfect cow. In the most practical sense, being dairy means that a cow has a body that promises great things in the milking parlor.
“We’re talking about openness to rib, a sweeping slant to ribs, overall angularity and length of neck,” explains CALS dairy science instructor Ted Halbach, who coaches the students on the UW-Madison dairy judging team. “It means she looks like she’s giving a lot of milk.” These are traits Halbach knows well. In his dozen years as coach, the UW judging team has won three national championships, including one in 2010. He won the contest himself as part of Wisconsin’s 1980 team, and he’s the son of a winner. His father competed and won as a UW senior in 1939.
But a lot has changed in the 90 years since the national judging contest began. 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.
That was demonstrated during one of Expo’s biggest events, the Friday night Holstein sale, when auctioneer Tom Morris brought down his gavel to sell a four-month-old calf for $87,000, the highest price paid all week. Two weeks before the auction, that calf had topped a ranking of Holstein heifers by Genetic Total Performance Index, a prediction of her future performance gleaned by scanning her chromosomes for the presence of certain genetic markers. Although the calf came from a long line of top performers, her outstanding genetic report card undoubtedly helped fuel the bidding.
When the University of Wisconsin proposed to set up a genetics department in 1910, it had the enthusiastic backing of W.D. Hoard, publisher of the influential Hoard’s Dairyman magazine. But he wanted a different name. “Genetics,” he said, was a technical term that the state’s dairy farmers wouldn’t understand.
It didn’t take them long to catch on. Through genetic selection, the dairy industry has been able to achieve astounding gains in the quality and quantity of milk that cows make. Since 1939, the nation’s dairy herd has shrunk by 60 percent, but it produces 20 percent more milk because the average cow’s production has more than quadrupled.
Those increases were accomplished through the development of a gene pool that is not only deep, but also extremely well cataloged. In the 1800s, breed associations began keeping herd books to record the pedigrees of high-performing animals. Soon after, the emergence of the Dairy Herd Improvement record system created a standardized way to compare various bulls and cows by keeping track of how much milk their offspring produced. Today the industry collects data on well over half of the nation’s nine million dairy cattle, recording not just milk yield, fat and protein, but also data related to things like health, fertility and milk quality. International producers have adopted the same framework, creating a vast database of cow performance that spans the globe.
For Kent Weigel, a CALS dairy scientist whose work focuses on genetic selection, the records offer a trove of data that can be mined to optimize breeding. “We can statistically analyze those data and figure out which are the best families to select as parents of the next generation,” he says. Currently, the way most breeding companies do that is to collect and sift data on the progeny of their breeding bulls. It’s dependable, says Weigel, but slow. “It’s at least five years before you get any information and can decide if it’s a good bull you want to keep or a bad bull that you want to get rid of.”
In contrast, genomic screening offers immediate feedback. Technicians can take a sample of blood or hair from a newborn calf, extract the DNA, and have an almost instant prediction of how she’ll perform in the herd. This is done by scanning the calf’s genetic code for the presence of certain markers, snips of DNA that are associated with various important traits. Roughly $150 will pay for a scan of 50,000 genetic markers. A new, slightly more expensive version will look at almost 800,000 markers.
“It’s not as accurate (as progeny testing)—not yet,” says Weigel. “We’re in this transition period, starting to move away from the progeny testing to the DNA testing. But decisions based on the DNA test results are taking a greater and greater role.”
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.”
Strength and dairy character
The revised standards emphasize more balance between strength and dairy character. “We’ve started to get people to think again that, yes, we want cows that produce a lot of milk, but we also want them to not kill themselves doing it,” Weigel says. “We want them to be able to maintain good health.”
Still, the ideal cow epitomized in the revised standards and in the show ring is geared toward a particular kind of dairying, in which cows live in large, open-stall barns and are fed a mixed ration that includes grain, forage, protein and mineral supplements. This is the dominant milk production system in the United States today, but plenty of cows across the nation and around the world live a different kind of life.
“Those cows are Ferraris,” says dairy farmer and UW-Extension agent Vance Haugen, describing the show cows at World Dairy Expo. “That’s wonderful, but I’m not going drive Ferrari on my back forty. I’d rather be driving my Jeep.” Haugen, who operates a pasture-based dairy farm, says he prefers cows with “a little more girth, maybe a wider muzzle so she can graze a little bit better. And smaller.”
Smaller is also better in Central America, says Ysidro Matamoros, an animal scientist from Honduras who brought a group of students to Dairy Expo. In his country, the average dairy herd has about nine cows that subsist on low-quality pasture and endure a brutally hot and humid climate. “She has to be smaller, because she has to dissipate a lot of heat,” he says. She also has to have some meat on her bones, literally. In Honduras—as in many places around the world—much of the milk comes from cows raised for both milk and meat.
What this means is that in an increasingly diverse global dairy industry, there is no ideal. One herd’s perfect cow might be a cull cow in a herd on the other side of the world.
The ability to find genetic markers for hundreds of discrete traits will continue to refine our ability to define perfection on a case-by-case basis. “The idea in the past was to look at what people thought the cow should look like intuitively. What they favored. What they liked to look at,” says Weigel. “Now you’ve got the data telling you what the cow should look like.”
But perfection will always be in the eye of the beholder. Brian Coyne says he will never forget that great Milking Shorthorn with the subpar udder that caught his eye during the national dairy judging contest. Nor will he forget his conversation with the Shorthorn judge in the final portion of the competition, in which contestants give their reasons for ranking the cows the way they did. Coyne dug deep into dairy-judging lexicon to explain why he picked that cow. He talked about her “decided advantage in dairyness, longer and cleaner head and neck and sharply chiseled top line.” But the judge wasn’t buying it. She pressed Coyne, asking how he would have rated the cows on udders alone. By that standard, he admitted, his first-place cow would have gone last.
“The judge gave me this funny look, and I was like, ‘Yeah, I started with my worst-uddered cow,’ and thinking, “I screwed this up really badly.”
Actually, he didn’t mess up much at all. He won the contest with the highest score in event history, and he did okay with the Shorthorns. The one he ranked first belonged in second place. She may not have been the perfect dairy cow, but she was a very dairy cow.
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