Making More With Less, As in Milk and Feed

Lou Armentano leads Dairy Science Feed Efficiency Initiative

By Kaine Korzekwa

Eat feed — get milked — repeat. Such is the life of a dairy cow.

The two actions are fundamentally linked. They affect a cow’s overall health and play a role, along with genetic factors, in how much she needs to eat for producing a lot of milk.

Ideally, feed rations will contain all of the necessary nutrients required to keep a cow healthy and also a cow will be able to efficiently use her feed to maximize milk production. Researchers at the University of Wisconsin–Madison’s Department of Dairy Science are passionate about making sure both of those things happen for Wisconsin’s dairy farmers today and into the future.

(Left to right) Dr. Lou Armentano and Dr. Kent Weigel

(Left to right) Dr. Lou Armentano and Dr. Kent Weigel

Professor Lou Armentano is part of a committee in the National Academy of Sciences called the National Research Council that is charged with updating the Nutritional Requirements for Dairy Cattle, which were last updated 2001. Armentano, along with Dairy Science Chair Kent Weigel, is also part of a five-year project to improve feed efficiency in cattle — a project that has the potential to save the Wisconsin dairy industry millions.

“Both of these projects have a direct effect on Wisconsin dairy farmers, as well as those across the country and the globe,” Armentano says. “I can’t imagine a more obvious and direct example of tying research that gets done at universities directly with the industry. There’s research that’s been done and rather than leaving it to sit in journals where only academics read it, we’re integrating it into an actual application with utility in the field.”

For his work with the NRC, the application is in the form of the “Nutritional Requirements for Dairy Cattle,” a book that sets the nutrition standards for all dairy cows. Its recommendations detail optimal levels for basic nutrients and even some supplements and toxins. Armentano explains how almost all dairy farmers use the ration balancing and models put forth in the book even if they don’t know it because large nutrition companies or private consultants incorporate it into their work.

“I consider it a part of my duty as a member of this department at the University of Wisconsin to be part of this committee,” he says. “The study of nutrition is pretty quantitative, especially in this case. We strive to look at all of the research and come up with a model where each feed component has a number associated with it that you then build a feed ration around.”

While the work with the NRC is about keeping dairy cattle healthy, another project in the Department of Dairy Science is trying to make cows more efficient in how they use that feed to make milk. The project is a $5 million National Institute Food and Agriculture grant in collaboration with Michigan State, Iowa State, Virginia Tech, Florida, USDA Agricultural Research Service, Wageningen University (The Netherlands), and the Scottish Agricultural College.

Professor Mike VandeHaar of Michigan State University was the leader of the project and said that having faculty from Dairy Science at UW–Madison was invaluable.

“I have known Lou since we were both in graduate school in the early ‘80s,” he says. “Lou, Kent, and the other faculty we worked with are all excellent scientists. The UW–Madison Department of Dairy Science is top-notch and well rounded. It was great to have them as part of this team.”

The project looked into the genetic components of feed efficiency, in particular a concept called residual feed intake (RFI). A cow with a low RFI is able to more efficiently turn feed into milk and body tissue when compared to her herdmates. For example, a cow that can eat less food than those around her but produce the same amount of milk as them is said to be more efficient.

“Feed expenses are a huge part of milk production,” Armentano explains. “So making cows more efficient is one of the best ways to remain viable and that means decreasing the amount of feed it takes to make milk.”

For years, farmers have selected cows based on how much milk they can produce. However, after a certain point, selecting for milk production becomes a diminishing return, says Armentano, and is no longer as effective a method as it once was. That is why the USDA was interested in exploring a complimentary selection method and was willing to fund grants to pursue it.

This new method involves amassing a database of feed consumption, milk production, weight, and genetic information for 8000 cows, which was a difficult, expensive, and tedious process because of how dairy cattle are fed and milked. By looking at the genetic information of the most highly efficient cows, the researchers will be able to find common gene markers between them.

“These genetic markers aren’t the actual genes increasing efficiency but they are inherited along with them so we’re looking for markers that a lot of highly efficient cows have in common,” says Dairy Science Chair Kent Weigel. “I like to think of these genomic markers as mile markers on an interstate. If we have all of the mile markers we can tell where important genes are located and if some cows have them compared with others.”

Weigel adds that the main purpose of the data gathered isn’t to solely select the most efficiency dairy cows. It’s also to select the best young bulls based on their genomic profiles and use them to breed other cows, thus producing more highly feed efficient cows. However, this selection for feed efficiency does not come at the sake of selecting for milk production, which is still highly important. “It will play a role in the breeding model so, for example, if you have several cows that all produce a lot of milk, it would be smart to select for the one with the highest feed efficiency and now we can do that,” explains Armentano.

A cow could be more efficient for a variety of reasons. She may digest food effectively, have an enzyme that allows her to better metabolize feed, or be less active than other cows so she doesn’t waste energy. The reasons are complex and should be explored by further research, Weigel says.

However, he also points out how the method could save dairy farmers millions. The old method of testing bulls was to study their progeny, which was time consuming and expensive — actually it would cost about $20,000 per bull to evaluate his daughters’ feed efficiency. Thanks to genomic testing and research projects like ours, selecting a bull that will transmit good feed efficiency can be done for less than $200 in the future.

“We can take this data, with our university herds serving as a reference population, and share it with the industry,” Weigel says. “Part of the project is having an open dataset to really aid the industry and help others add to the research. The blending of genetics and nutrition research in this project is very valuable.”

Those interested in this research can learn more about it at the 2015 Dairy Research Showcase on Nov 3. The Showcase, designed to highlight the department’s research, extension and instructional efforts, will feature several aspects of the study. The program will also include graduate student presentations on other current research initiatives and a poster session.

To attend the Dairy Science Showcase, please register online by October 23rd at dysci.wisc.edu/showcase/. Registration is free and covers complementary lunches and an ice cream social for participants. All activities will be held at campus’ Dejope Hall, located at 640 Elm Drive. Parking passes can be purchased when registering for the event.