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The proof is in the pasture: Grass-fed milk verification

Tamara Scully for Progressive Dairy Published on 11 September 2019

Milk and dairy products made from grass-fed cows are hitting grocery store shelves. Adding a grazing component is not only a consumer-friendly approach, it is also a viable economic one for many dairy farmers today.

Some of that economic benefit comes from market premiums. The USDA’s National Organic Program (NOP) certification requires a minimum of 30 percent of dry matter intake (DMI), on average, from in-season grazing plus a minimum of 120 days on pasture. These standards may satisfy some farmers and consumers, although uproar has focused on large dairies that seem to be skirting the pasture rule. A growing focus on 100% grass-fed dairy farming is emerging from both the farmer and consumer sides of the equation.



With so much riding on distinguishing milk from grazed cows, how does the dairy industry ensure that milk actually does come from grazed herds which meet some type of minimum standards and prevent imposters from duping consumers and hurting the farms that are actually making “value-added” milk through intensive grazing management?

Third-party certification

The American Grassfed Association’s dairy standards allow no grain feeding, require 60 percent DMI from pasture grazing and 150 grazing days minimum. Just as in certified organic regulations, there are guidelines for animal care, pasture management, allowed supplements and medications and more. Producers under this label do not need to also be USDA-certified organic.

Some USDA organic certifiers, such as Pennsylvania Certified Organic, have developed add-on labels for certified organic producers who are making milk from 100 percent grass.

The Certified Grass-Fed Organic Livestock Program is a new, voluntary program that has created a national standard for grass-fed livestock production. Maple Hill, Organic Valley and Natural by Nature products are now touting this new grass-fed label. Designed to standardize the management parameters of 100% grass-fed milk, cows must graze for a minimum of 150 days and receive an average DMI of 60 percent from pasture. The certification is an add-on to the USDA-certified organic label.

Beyond the label

While third-party certification may go beyond the NOP standards for grazing, they are still a labeling program. Consumers and farmers are trusting a certifying agency to see that the regulations are upheld. A part of the perceived problem with NOP standards is the accusation of lack of oversight by certifying agencies.


Is there any other way to ensure that milk which claims to come from grass-fed cows actually does?

Bradley Heins, University of Minnesota, West Central Research and Outreach Center, published a recent study examining the rumination data from a grazing herd and a low-input conventional herd at the center. The four-year study found that, on average, the grazing herd spent 15 additional minutes per day on rumination.

The average activity level, as measured in two-hour blocks, was higher for the grazing-based cows for the majority of the day. The study was designed to determine whether behavioral monitoring systems could provide grazing dairy producers with information to help better monitor their herds.

“I don’t think that activity monitoring would ‘prove’ that a herd is grass-fed or not. But it may be a starting point. I think it may give some indications that they are at least grazing,” Heins said.

Another data-based tool that could prove helpful in verifying grass-fed milk really is from pastured cows involves analyzing the fatty acid, omega-3 and omega-6 profiles, Heins said.

Data from a three-year study in which the fatty acid profiles in milk from certified organic cows fed a 100% forage-based diet, as well as those from milk from cows fed 12 pounds of grain per day and from a low-grain-supplementation group fed 6 pounds of grain per day, were measured via gas chromatography.


Notable differences in these profiles were found based on the amount of grazing. Other differences included lower lauric, myristic and palmitic acid levels in the milk from 100% grass-fed cows. Stearic, oleic, linoleic and linolenic values were elevated in the grass-fed cows compared to the other groups. The study clearly showed the time spent grazing does impact milk’s nutritional values.

“The fatty acid profile and omega-3 and omega-6 might be the best, but they would not be perfect as well,” Heins concluded.

The high omega-3 content in grass-based milk was also the impetus behind the recent Iowa State University and Leopold Center study using fluorescence spectroscopy to measure the amount of chlorophyll metabolites in milk samples. They found that milk from grass-fed cows has higher levels than those from grain-supplemented herds. The method uses light and requires little preparation or expense.

Levels of chlorophyll were substantially elevated in grass-fed cows from Radiance Dairy, a certified organic dairy owned by Francis Thicke. Chlorophyll metabolite levels from this herd’s milk was compared to that from certified organic milk and conventional milk brands from the grocery store.

The cows at Radiance Dairy receive more DMI from pasture than required by organic regulations, with the majority of the diet, year-round, coming from grass. The fluorescence spectroscopy found the level of chlorophyll from Radiance Dairy to be 0.11 to 0.13 micrometer (μM), while off-the-shelf certified organic milk levels were 0.07 to 0.09 μM and conventional milk levels a mere 0.01 to 0.04 μM.

Visualizing grass-fed milk

“The subtle seasonal flavors of our pastures,” which happen naturally as pasture forages change throughout the season, are the signature of the Grassmilk brand, as per the Organic Valley website. It’s a marketing approach unlike the conventional milk market’s emphasis on product consistency, achieved via commingling milk for dilution effects and using processing techniques to neutralize off flavors.

The color of pasture-based milk fluctuates seasonally as well and typically has a more pronounced yellow color, a result of carotenes which concentrate in the butterfat. The yellow hue is most noticeable in unhomogenized milk or in cheese, butter and cream from grass-fed herds.

Change is here. Dairy farmers are demanding recognition for their management and husbandry skills, and are looking to differentiate their farms from the large and very large dairies – confined and otherwise – which are flooding the markets. If the emerging 100% grass-fed dairy market is any indication, authenticity in the marketplace is going to win the trust of a growing segment of consumers who are eager to reward those farmers who can prove their worth. A new era of dairy transparency may bring with it the economic boost many dairy farmers need, and grass-fed milk may become the new normal for a certain percentage of the consumer – and dairy farming – population.  end mark

Tamara Scully, a freelance writer based in northwestern New Jersey, specializes in agricultural and food systems topics.

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