Linda Benedict, Prinyawiwatkul, Witoon, Scaglia, Guillermo | 11/12/2014 10:51:04 PM
Fatemeh Malekian, Witoon Prinyawiwatkul, Damir D. Torrico and Guillermo Scaglia
Forage-fed and grain-fed beef differ in a number of qualities, including their fat content. Meat from forage-fed cattle is lower in total fat, and if the meat is very lean, it can have one-third the fat as beef from grain-fed animals.
In a study conducted by LSU AgCenter and Southern University Agricultural Research and Extension Center scientists, a total of 54 fall-born steers, which were purchased from a single source to minimize initial variations, were randomly assigned to one of the three forage feeding systems as described in the article Beef Cattle Performance on Three Forage Systems. Ribeye steak samples from steers finished on one of the three forage systems (labeled S1, S2 and S3) and a grain-fed choice steak (labeled C), purchased from a local supermarket, were analyzed in duplicate for total lipids, protein, moisture, ash and fatty acids.
Fat content in grain-fed beef was four times higher than forage-fed beef (Table 1). Because meat from forage-fed animals is lower in fat than meat from grain-fed animals, it is also lower in calories. The protein concentration was much greater in forage-fed beef (Table 1). Mineral content (ash) was greater in forage-fed beef (Table 1).
Red meat has high saturated fatty acid content. Saturated fatty acids build up on artery walls and make them hard, a condition known as atherosclerosis. This condition makes the heart beat faster to push blood through arteries, which in the long run will cause high blood pressure. There are three main types of saturated fatty acids found in red meat: stearic acid, palmitic acid and myristic acids. In this study, forage-fed beef and commercial grain-fed beef had almost the same portion of stearic acid, 28 percent to 29 percent. Palmitic acid content was similar for forage-fed and commercial grain-fed beef at 28 percent. Myristic acid was as follows in the samples: S1, 2.9 percent; S2, 3.8 percent; S3, 2.4 percent; and C, 3.3 percent.
Polyunsaturated fatty acids are subdivided into two categories, omega-6 and omega-3, based on location of the double bonds in the fatty acid chain. Omega-6 fatty acids are common in grains and vegetable oils.
Omega-3 fatty acids are common in plant lipids and fish oils. Omega-3 fatty acids are essential nutrients for human health. “Essential” means that our body cannot make them, and we must get them through food. There are two critical omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic (DHA), that the body needs. Sources such as walnuts and flaxseeds contain a precursor to omega-3, alpha-linolenic acid, that the body must convert to EPA and DHA. EPA and DHA are the building blocks for hormones that control immune function, blood clotting and cell growth, as well as components of cell membranes.
Omega-6 fatty acids are also considered essential fatty acids. Along with omega-3 fatty acids, omega-6 fatty acids play a crucial role in brain function, as well as normal growth and development. In general, hormones derived from the two classes of essential fatty acids have opposite effects. Those from omega-6 fatty acids tend to increase inflammation, blood clotting and cell proliferation, while those from omega-3 fatty acids decrease those functions. Both families of hormones must be in balance to maintain optimum health. For general health a balanced ratio of omega-6 to omega 3 should be in the range of 2:1 to 4:1. However, even lower ratios are recommended (1:1). In the literature, the average ratio of omega-6 to omega-3 in forage-fed beef is 1.53:1. In grain-fed beef, this ratio increases to 7.65:1.
In this study, the concentration of omega-3 fatty acids was three times greater in forage-fed beef (S1, S2 and S3) than in grain-fed beef (C) (Table 2). The ratio of omega-6 to omega-3 in forage-fed beef was much healthier than in grain-fed beef (Table 2).
Conjugated linoleic acid (CLA) has been shown to possess anticarcinogenic effects. Beef is an excellent dietary source of CLA, and forage-fed beef contains an average of two to three times more CLA than grain-fed beef. In this study, beef from all three forage-fed systems showed significantly greater concentrations of CLA compared to commercial grain-fed beef.
Based on the results from this study and others, forage-fed beef is lower in fat content and higher in protein content. It contains more omega-3 fatty acids and more CLA. Forage-fed red meat is more nutrient dense than grain-fed. Even though forage-fed beef is more expensive, it may be a better choice for Louisiana families than grain-fed beef. Louisiana has one of the highest rates of obesity in the country, estimated at 34.7 percent. A scientific consensus on the relationship of obesity to such diseases as diabetes, heart disease, stroke and some forms of cancer has been documented.
Fatemeh Malekian is a professor in the Department of Food Science and Nutrition, Southern University Agricultural Research and Extension Center, Baton Rouge. Her co-authors are Witoon Prinyawiwatkul, professor, and Damir D. Torrico, Ph.D. student, both in the School of Nutrition and Food Sciences; and Guillermo Scaglia, associate professor, Iberia Research Station, Jeanerette.
This article was published in the fall 2014 issue of Louisiana Agriculture.