In The Omnivore’s Dilemma (The Penguin Press, New York, New York, 2006), Michael Pollan describes in vivid prose the nightmare world of CAFOs (confined animal feeding operations) and the “polluted water and air, toxic wastes, novel and deadly pathogens” they have produced “in their short history.” It is with some relief that Mr. Pollan also focuses on the alternative “bovine dining scene” of cows at pasture feeding on grass: “harvesting their own feed instead of waiting for a dump truck to deliver a total mixed ration of corn that had been grown hundreds of miles away and then blended by animal nutritionists with urea, antibiotics, minerals, and the fat of other cattle in a feedlot laboratory.”
There is little doubt that, in Mr. Pollan’s words, “growing meat on grass makes superb ecological sense: It is a sustainable, solar-powererd food chain that produces food by transforming sunlight into protein.” Further, cows are ruminants (like sheep and bison) and “have evolved the special ability to convert grass-which single-stomached creatures like us can’t digest-into high quality protein.” Pollan calls “the rumen” the most highly evolved digestive organ in nature: “About the size of a medicine ball, the organ is essentially a forty-five-gallon fermentation tank in which a resident population of bacteria dines on grass.” Mr. Pollan makes a convincing case that feeding corn to cows “violates the biological or evolutionary logic of bovine digestion.”
Mr. Pollan’ also asserts in The Omnivore’s Dilemma “that many of the health problems associated with eating beef are really problems with corn fed beef.” This contention now finds support in a thorough review by agricultural experts of the scientific research spanning three decades, which focused upon the differences in nutritional quality between grass-fed and grain-fed cattle, conducted by Patrick Doyle, Amber Abbott, and Cynthia A. Daley (California State University, Chico) and Glenn A. Nader and Stephanie Larson (University of California Cooperative Extension Service, Davis). The experts’ review of the scientific literature has confirmed that grass-fed beef is by far superior nutritionally to grain-fed beef [www.nutritionj.com/content/9/1/10].
Nutritionists agree that an imbalance of dietary cholesterol and fats are the primary cause of cardiovascular disease (CVD), and that the overall consumption of saturated fatty acids (SFAs), trans-fatty acids (TAs) and cholesterol should be reduced while the intake of n-3 polyunsaturated fats should be increased. The scientific review by the California-based agricultural experts concluded that grass-based diets for cows enhance (i) total conjugated linoleic acid (CLA) isomers, (ii) trans vaccenic acid (TVA) which is a precursor to CLA, and (iii) omega-3 fatty acid (FA). Grass-fed beef tends toward higher proportion of cholesterol neutral stearic fatty acid, and less cholesterol-raising saturated fatty acids (SFAs).
In addition, a healthy diet “should consist of roughly 1 to 4 times more omega 6 fatty acid than omega 3 fatty acid, and there are significant differences in this “n-6: n-3 ratios” between grass fed and grain fed beef: 1.53 grass fed; 7.65 grain-fed. (The reviewers noted that the typical American diet has an extraordinary 11 to 30 times more omega 6 fatty acid than omega 3 fatty acid, which may explain the rising rate of inflammatory disorders). Cattle fed primarily grass significantly increased the omega-3 content of the meat and also produced a more favorable omega 6 to omega 3 ratio than grain fed beef.
Further, grass-fed beef have elevated carotenoid content (precursor for Vitamin A) and elevated precursors for Vitamin E, as well as powerful cancer fighting antioxidants such as glutathione (GT) and superoxide dismutase (SOD) as compared to grain-fed beef. Ruminants on high forage rations pass a portion of the ingested carotenoids from the grass into their milk and body fat. Pasture fed steers incorporate significantly higher amounts of beta-carotene into muscle tissue as compared to grain-fed animals: a 7-fold increase in B-carotene levels over grain-fed steers. Plus, grass-fed beef has an overall lower fat content to grain-fed beef.
The review also lends support to the contention that animals should arguably be “finished” on 100% grass or pasture-based diets to maximize the favorable lipid profile and to guarantee the elevated antioxidant content because “shifting diets to cereal grains will cause a significant change in the fatty acid profile and antioxidant content within 30 days of transition.” In sum, the “pastoral approach to beef production,” according to the experts’ review of the scientific literature, results in an enhanced nutrient claim for grass-fed beef products, which is better for human health.
In Cultivating Science, Harvesting Power- Science and Industrial Agriculture in California (The MIT Press, Cambridge, Massachusetts, 2008), Christopher Henke, an Assistant Professor of Sociology at Colgate University, focused on the role of agricultural scientists, employed by Cooperative Extension of University of California (UC), in assisting growers in the development of industrial scale agriculture in California’s Salinas Valley. Growers invested a great deal of effort in “intervention” with Mother Nature in order to transform the valley into a “unique” place, and Prof. Henke detailed the role of agricultural scientists in this extraordinary transformation of an American landscape. For local food advocates, it is a hopeful sign to see that UC cooperative extension agricultural scientists have utilized their expertise to participate in this thorough review of the scientific literature on the differences in nutritional quality between grass-fed and grain-fed cattle. The major conclusion that grass-fed beef is superior to grain-fed beef lends significant support to Michael Pollan’s brilliant critique of industrial agriculture in The Omnivore’s Dilemma [FWB 1/28/11].