Conventional vs. organic agriculture – the battle continues

An article was published earlier this week comparing the nutritional content of milk from organically raised cows to that from conventional dairies. The principle finding in this report is that “organic milk contained 25% less ω-6 fatty acids and 62% more ω-3 fatty acids than conventional milk, yielding a 2.5-fold higher ω-6/ω-3 ratio in conventional compared to organic milk (5.77 vs. 2.28).” (ω-3 fatty acids are considered to be “healthy” and you’ve probably heard of them in association with fish consumption.)

Of course, the popular press has had a field day with this, with such headlines as “Study finds organic milk is more nutritious.” This of course is nonsense, because the researchers didn’t study the health effects on people consuming the milk. But for argument’s sake, let’s assume this might be true and move on to the study itself.

What researchers actually found was that cows who feed primarily on pasture grasses and other forages (the “organic” cows) had elevated ω-3 fatty acids compared to those receiving a primarily grain-based diet (the “conventional” cows). This isn’t new information – other studies (such as this one) have consistently demonstrated this.

The problem with this newest paper is the inaccurate terminology used to describe the study. It really has nothing to do with whether the cows are raised organically or conventionally – it has to do with what they eat. A better experimental design would have included multiple comparisons among “organic” cows (who by default are grass-fed), “conventional” cows that are fed a grain diet (typical with large operations), and “conventional” cows that are pasture-raised (common with smaller farms that don’t want to jump through the organic certification hoops). I’m betting that the milk from this last group of cows wouldn’t be much different from the “organic” cows.

The upshot of using such imprecise terminology is that the message is lost amid the furor of the ongoing organic vs. conventional agriculture battle. Readers erroneously jump to a  value-based conclusion – i.e., organic is “better” than conventional.

In my opinion, there’s no excuse for this. The experts who reviewed this article should have pointed out the loaded language and insisted on a change in terminology. (You might be interested to follow the comments on this article, one of which alludes to misleading terminology.)

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Linda Chalker-Scott

Dr. Linda Chalker-Scott has a Ph.D. in Horticulture from Oregon State University and is an ISA certified arborist and an ASCA consulting arborist. She is WSU’s Extension Urban Horticulturist and a Professor in the Department of Horticulture, and holds two affiliate associate professor positions at University of Washington. She conducts research in applied plant and soil sciences, publishing the results in scientific articles and university Extension fact sheets. Linda also is the award-winning author of five books: the horticultural myth-busting The Informed Gardener (2008) and The Informed Gardener Blooms Again (2010) from the University of Washington Press and Sustainable Landscapes and Gardens: Good Science – Practical Application (2009) from GFG Publishing, Inc., and How Plants Work: The Science Behind the Amazing Things Plants Do from Timber Press (2015). Her latest effort is an update of Art Kruckeberg’s Gardening with Native Plants of the Pacific Northwest from UW Press (2019). In 2018 Linda was featured in a video series – The Science of Gardening – produced by The Great Courses. She also is one of the Garden Professors – a group of academic colleagues who educate and entertain through their blog and Facebook pages. Linda’s contribution to gardeners was recognized in 2017 by the Association for Garden Communicators as the first recipient of their Cynthia Westcott Scientific Writing Award. "The Garden Professors" Facebook page - "The Garden Professors" Facebook group - Books:

4 thoughts on “Conventional vs. organic agriculture – the battle continues”

  1. Good explanation but most all grazing dairies and organic farms feed at least a little grain. As a grazing dairy farmer myself, the difference isn’t in grain or forage, but fresh forage vs stored feed as you can see the Organic (grazing dairy) advantages are eliminated during the winter months because all cows are being fed similarly… all stored feed. Very very few farms feed 100% forage, nearly impossible to get enough energy into today’s dairy cows on forage alone and takes a larger landbase to grow enough forage. So many graziers might feed rations that are 80:20 to 70:30 forage to grain. Conventional dairies that harvest all forages then formulate and mix balanced rations back to the herd as well as grazing and organic dairy farms thru winter months will typical feed rations that are 70:30 to as high as 50:50 Forage to Grain. Really unheard of to feed a ration higher than 50% grain. Not healthy on a cow’s digestive system nor is it economical.

  2. Thanks for referencing the article. I haven’t been convinced that organic milk has more nutritional benefits but found this information to be compelling. The article does include data from “conventional” dairy cows in Northern California that are primarily pasture raised and have lower w6/w3 ratio. As the authors note, there are feed standards for organic milk and none for conventional milk. Very interesting.

  3. i don’t understand what the hypothetical underlying mechanism is.

    as linda pointed out, the biggest difference between organic and conventional is one farmer applied for certification and the other didn’t. the actual farming techniques can be very similar or very different. i would guess that studies like this are hard to replicate.

  4. It could be that a reviewer did indeed object to misleading terminology but was overruled by the Editor. It happens.

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