Cows Get Nutrition Advice Too

  • Article
  • 3 min read August 10, 2016

You've heard of sports nutritionists -- experts who are specially trained to help athletes adopt a nutritious lifestyle in order to improve their health and performance. But maybe you didn’t know that there are experts in the dairy world who are specially trained to assess and optimize the diets of the “athletes” on a dairy farm: the milking cows. We talked with one dairy cattle nutritionist, Mary Beth de Ondarza, about her work with dairy farmers and their cows.


Why do farmers work with a nutritionist like you?

Dairy farmers want to keep their cows healthy, so they can give plenty of milk and live a long life.  Feeding them a balanced diet is an important factor, just like it is for humans.

What makes dairy cows unique?

Dairy cows are ruminants, meaning that their stomach – or rumen -- is like a large fermentation vat. It contains bacteria that digest the cow’s feed, and convert it into energy and protein. 

Keeping that bacteria in the rumen healthy allows the cow to digest fiber, and keeps her healthy and productive. And because of her rumen, cows can convert hay and other fibrous feeds into protein-rich milk that humans can use to keep us healthy and productive, too.

What is a typical diet for a dairy cow? 

Cow diets will vary depending on region of the country or world primarily because of differences in available forages and feeds. Where I work in the Northeast U.S., about 50-65 percent of the milking cow’s diet will be forages grown by the dairy farmer. The rest of the diet will be a combination of corn, soybean, canola, by-product feeds from wheat milling, corn milling, and ethanol industries and some additional minerals and vitamins. In Florida, you will often find citrus by-products in the diet. In California, you will find almond hulls in the diet. Cows are great food recyclers and can use many by-products that would otherwise by wasted.

What's one thing that might surprise people about a dairy cow's diet?  

When I tell people that I am a dairy nutritionist, they often look at me like I am crazy, especially if I tell them that I have a Ph.D. in dairy cattle nutrition. Some think that dairy farmers simply throw a bale of hay in front of a cow and she makes milk. But, just like we have advanced with computers and cell phones and the science of feeding humans in the 21st century, the science of feeding dairy cows has advanced too. This has helped our farmers to greatly improve both the health and performance of their cows, and helps the dairy farm to be both environmentally and economically sustainable.

What is your favorite part of your job? 

I love it when I hear back that cows on a farm have responded positively to a diet change that is good for them and meets the farmer’s goals, too!

What inspires you to do this work? 

I have always loved dairy farming. I find that it very satisfying to help dairy farmers find ways to improve the health and productivity of their animals as well as increase farm profitability and sustainability.