After completing my studies in beef cattle nutrition, I have found that, frankly, the good news I used to hear about grass-finished beef is not all that great, and the bad news about conventional beef is not all that bad. Although I respect niche-market cattlemen for their creation of an artisanal product—I really am particularly fond of the grass-finished taste—I can finally admit that whatever you and I have heard from a handful of avant-garde critics about ecological and nutritional superiority is…hype.
USDA defines “Grass-Fed” as the product of animals whose diet is solely forage-based, without any inclusion of grain. I’m using the term “Grass-Finished” because all cattle, no matter the system, are reared on their grass-consuming mother’s milk and eat forage until the “finishing” stage that brings them up to harvest weight. They either remain on pasture and keep eating forage or enter a feedlot and consume a mixed diet of corn, grain and oilseed by-products, and preserved forages like alfalfa hay or silage. I’ll refer you to Anne Burkholder’s blog if you’d like to know more about how a feedyard is managed.
While studying ruminant nutrition, I learned that “you are what you eat” somewhat applies to humans and other monogastrics (pigs, horses, etc.), but not quite as much to ruminants. Sort of in the same way milk cultures in to yogurt, ruminants use microbes to “culture”, or ferment, their diet into metabolic intermediates (volatile fatty acids…like lactic acid in yogurt) and microbial bodies (microbial crude protein…like what most of yogurt consists of). What a cow actually digests is much different than what she originally ingests. That helps explain…
1. Omega 3 content: 0.052 g (3 oz. Grass-fed); 0.039 (3 oz. conventional); Yes, grass-fed beef will consistently have a statistically significant increase in Omega 3, but this difference is inconsequential compared to a 3 oz. serving of salmon, which has 1.83 g. The daily recommended intake of Omega 3 is 1 g…fish oil, yes please…60 ounces of grass-fed beef, no thank you. Indeed, the ratio of Omega 3 to 6 in grass-finished beef, being lower than conventional beef, is more optimal (about 1:4 vs. 1:10; Schmid et al., 2006; Leheska et al., 2008) in the way of reducing arterial swelling, improving circulation, and reducing triglycerides (Morris et al., 1993; Harris, 1997; I will make a qualifying statement about ratios in the section on Fats). I have seen data showing that some grass-finished beef has as much as 0.10 g Omega 3 (Leheska et al., 2008; French et al., 2000), but this value is not likely to improve because of microbial fatty acid alteration in the rumen (natural biohydrogenation – turning polyunsaturated fats like omega 3's into saturated and trans fats). In fact, beef from feedlot-fed cattle have much greater potential to increase in Omega 3 values because of the higher passage rate which reduces microbial interference with the dietary fats. If feedlot animals are fed Omega 3s with linseed or algal oil, their beef increases in Omega 3 to the same level as grass-finished beef (Razminowicz et al., 2007).
2. Vitamins A and E from grass-fed beef might be found in quantities 7 times higher than conventional beef, but a serving will only provide up to 2% of the daily value for both vitamins (Daley et al., 2010). Beef in general is not a good source of these vitamins.
3. Fats: Although grass-finished beef has consistently less fat overall than does conventional beef (about 10% less fat, Leheska et al., 2008), the types of fat grass-finished beef offers concerns me. If you ever eat a burger made of grass-fed beef, you'll notice something strange. The grease that falls from the burger to your plate will in a few minutes harden into a hard wax-like substance, reminiscent of candle drippings. Conventional beef patties drip grease that remains oily and doesn't harden much as it cools. As someone with hypercholesterolemia, I am very sensitive to monounsaturated fat—saturated fat ratios. When I lived in Spain during college, I didn’t watch this and almost went on statin medication as a skinny 21-year-old! Monounsaturated fat (MUFA; think olive, canola, pecan oils) makes my HDL (good) cholesterol rise, while saturated fat (SFA; think hard fats like butter, grizzle) makes my LDL (bad) cholesterol rise. Your HDL/LDL can reflect your MUFA/SFA dietary intake (Adams et al., 2010; Gilmore et al., 2011). Grass-fed beef has less MUFA than SFA (ratio of 0.71 – 0.95), while conventional beef has a more optimal ratio of 1.1 – 1.31. Keep in mind that I may cancel out beef's positive "ratio" effects by over-consuming Omega 6 or SFA, so that my overall diet ratio may be far from optimal. Grain-finishing deposits more MUFA, especially where the beef is marbled, while grass-finishing deposits more SFA and even trans fats (3 g in Choice grass-finished beef vs. 0.14 g in Choice conventional beef per serving) because of ruminal biohydrogenation (Smith et al., 2009; other data c/o Dr. Smith). For lower amounts of trans-vaccenic fats, I recommend buying conventional beef or grass-fed beef that grades USDA Select or lower.
4. CLA: The alleged benefits of CLA (conjugated linoleic acid, a fatty acid only available in products from the cattle/sheep family) are that it fights cancer, reduces arterial inflammation, and lowers body fat. These have been confirmed in laboratory rodent studies (Schultz et al., 1992; Parodi, 1994; Belury, 1995; Nicolosi and Laitinen, 1996; Pariza et al., 1996) but not in human studies (Brown et al., 2010). Grass-finished beef can offer up to two or three times as much CLA as conventional beef, but both are still a good source at ranges of 0.1 – 0.15 g per serving (Leheska et al., 2008; French et al., 2000).
While scientific credence for health advantages of grass-finished beef wanes, I still buy both types of beef, because both provide 29 different cuts of lean (< 10% fat) meat that don’t even need seasoning like other meats do. As someone prone to anemia and upper respiratory issues that is also at risk for Alzheimer’s disease, it’s good to know that a serving of beef has three times as much iron, six times as much zinc, and seven times the vitamin B12 of chicken. Plus, it’s nice to get as much iron in one serving of beef as there is in three cups of raw spinach, or as much protein as 230 calories of raw tofu, 374 calories in beans, or 670 calories in peanut butter (25g protein from 180 calories of lean beef!).
Any animal management system that does not advance the growth rate of its animals will be inadvertently spending resources for maintenance more so than production, which is wasteful. Slow growing animals will consume more food and water and excrete more solid and gaseous waste per unit of meat or milk they produce. Grass-finished cattle go to market at almost twice the age and at lighter weights than do grain-finished cattle. In light of this…
1. Land Use: Some neo-agricultural purists advocate finishing all beef produced in this country on pasture. Putting climatic limitations and weather capriciousness aside, let’s say all the acres of grain crops used to finish cattle at feedlots were converted to pasture. It requires 3 times more land to finish cattle on grass than it does to grow crops for finishing cattle in a feedlot (Avery & Avery, 2007). In order to produce the same amount of beef, an additional 60 million acres of non-forested land that receives > 38” annual rainfall would be required to support this goal (Capper et al., 2009). Did anyone find Atlantis yet?
2. Methane Production: Cattle consuming grass produce as much as 3 times more methane than cattle on a feedlot diet. This has to do with different fermentative pathways that can operate in response to different diets. Since I’m a nutrition nerd, please post a comment and ask about it you’re curious. However, I typically view cattle methane production as a moot point because cattle contribute to only about 15% of world totals (Wahlen et al., 1993…see post “Bitten hands that feed…”).
3. Sanitation: Free-ranging cattle like those on a grass-finished system are free to excrete wastes directly into groundwater. Waste deposited by feedlot cattle is contained and treated. Feedlots must follow stringent regulations for water quality control. They must submit a site-specific Pollution Prevention Plan that is engineered to “prevent and limit discharge of pollutants to surface and ground waters” and must include a plan for a catastrophic 100-year, 24-hour rainfall event. For more details, read Avery & Avery, 2007.
I buy beef in general because it keeps open range and wildlife habitat profitable as ranchland instead of as pavement or row crops. Beef cattle management protects 75% of wildlife habitat in the United States from development.
What do you think?