Many research have shown that the nutrients in beef can vary depending on what the cows eat. The way cows are fed can have a major impact on the nutrient composition of the beef. All cows do feed on pasture for the first six months to a year of their lives, but most finish at a feedlot on a concentrated mix of corn, soy, grains, and other supplements, plus hormones and antibiotics. The conventionally raised cows are often given drugs and hormones to grow faster. The cows live there for a few months and are then moved into the factory for slaughtering. Unlike the grass-fed cows which may continue to live on grassland for the remainder of their lives.
Grass-fed beef is up to three times leaner than grain-fed beef and usually contains less total fat than grain-fed beef. Meaning grass-fed beef contains fewer calories gram for gram. Grass-fed beef also contains higher levels of the beneficial nutrients including zinc, iron, phosphorus, sodium, and potassium. It is also an excellent source of vitamin B12 and very good source of protein, niacin, vitamin B6, selenium, and zinc. Studies have shown that grass- fed beef also contains two newly discovered "good" fats, and more beta carotene, vitamin E and folic acid. 
Grassfed beef is not only lower in overall fat and in saturated fat, but it has the added advantage of providing more omega-3 fats. More heart-healthy omega-3 fatty acids. Grass-fed beef is better for human health than grain-fed beef in so many ways. Some of these are lower in total fat, higher in total omega-3s, excellent source of Vitamin E and higher in minerals, calcium, magnesium and potassium.
Grass-fed beef is high in anti-inflammatory nutrients (CLA & Omega-3, not to mention higher in micronutrients), whereas grain-fed beef is not as high in these. Therefore it is possible (just a hypothesis of mine!) that the meat lobby knows that grain-fed beef is contributing to long-term chronic inflammation in the general population making people more susceptible to chronic disease. If the meat industry were to fund studies or speak out more, it might draw attention to the unfavorable nutrient profile of grain-fed beef - especially since in observational studies we already have that consistent bias of red meat being consumed in higher quantities by people following unhealthy lifestyles.
If there actually is a negative impact of grain-fed red meat on human health, why draw attention to it? Funding junk science may happen, but it's not necessarily easy. Not to mention, anybody who sees "funded by XX Meat industry" won't believe the study for a second, no matter its validity.
But also, the meat industry might see any publicity as bad publicity. If they were to try and advertise any benefits of meat, PETA, CSPI, and other crazy groups would have a field day. The industry may have made a calculation that they can sell more meat by keeping their mouths shut.

Grass-fed beef definitely has its advantages, but it is typically more expensive, and I’m not at all sure that’s a bad thing. It is important to keep in mind that even conventional, grain-fed beef is very healthy. Regular grain-fed beef is also loaded with Vitamin B12, B3 and B6.  There can also be subtle differences in taste. Grass-fed beef is often leaner and there may be some differences in texture. There is a dark side even to grassfed, it takes a lot of grassland to raise a grassfed steer. Some people prefer grass-fed, others are grain-fed.

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