The meat from animals raised on pasture has been listed as one of the most nutritious. Several studies have concluded that the product contains high concentrations of beta carotene and α-tocopherol, increased levels of Omega 3 fatty acids, and more desirable higher proportion of Omega-3: Omega-6 and high levels of conjugated linoleic acid, all such substances known of favorable effects on human health.

Provitamin A: Beta carotene

         Beta carotene, an antioxidant liposoluble, is derived from the Latin name carrot, which belongs to the family of natural chemicals known as carotenes or carotenoids. The carotenes produce the yellow and orange found in fruits and vegetables and converted into vitamin A (retinol) by the body. While the artificial supplementation of vitamin A in excess can be toxic, the body converts only the necessary amount of vitamin A beta carotene in the food coming.

         Vitamin A is a liposoluble vitamin essential, important for normal vision, growth of bone, reproduction, cell division and differentiation. It is responsible, specifically, for maintaining the surface film of the eyes and mucosa of the respiratory, urinary and intestinal. The total integrity of the skin and mucous membranes is maintained by vitamin A, creating a barrier to bacterial infections. It is also involved in regulating the immune system, supporting the production and function of white cells.

         Descalzi et al, 2005 found that livestock grazing created to incorporate significantly larger amounts of beta carotene in muscle tissue when compared to animals confined. Concentrations vary from 0.63 to 0.45 g / g in the cattle pasture and 0.06 to 0.5 g / g confined to cattle, a tenfold increase in levels of beta carotene.

Vitamin E: alpha-tocopherol

         Vitamin E is a liposoluble vitamin that exists in 8 different forms with powerful antioxidant activity, the more active the alpha-tocopherol. Antioxidants protect the cells against the effects of free radicals. Free radicals are potentially damaging by-products to organic metabolism and may contribute to the development of chronic diseases such as cancer and cardiovascular diseases. Vitamin E also blocks the formation of nitrosamines which are carcinogens formed in the stomach on account of nitrites consumed in the diet. The current recommended intake of vitamin E is 22 IU (natural sources)) u 33 IU (synthetic source) for women and men (Harvard School of Public Health, USA, 2002).

         The concentration of alpha-tocopherol naturally found in meat from cattle confined is approximately 2.0 g / g of muscle while in the pasture of cattle varies from 5.0 to 9.3 mg / g of tissue, depending on the type of forage the animal assessable. The forage increases the levels of alpha-tocopherol on 3 times, necessary to extend the shelf life of the meat off. Vitamin E acts on post-mortem to delay the oxidative deterioration of meat, a process in which the myoglobin is converted into metamioglobina, giving the appearance dark meat.

Omega 3 fatty acids: Omega 6

         Omega 3 fatty acids are considered essential, meaning that are essential to human health but can not be produced by most mammalian species. For this reason, must be obtained from food.

         The essential fatty acids (EFAs) are polyunsaturated and grouped into 2 families: the Omega-6 and the Omega-3. Although there is a minimum difference in their molecular structure, the 2 families EFAs act differently in the body. While the metabolic products of acid Omega-6 promotes inflammation, blocking blood and growth of tumors, the Omega-3 acids act in a manner completely opposite. However it is important to maintain balance between the two types in the diet, as these 2 substances work together to promote health.

         Inadequate measurement essential from these fatty acids contributes to the development of diseases. A healthy diet should consist of 1 to 4 times more omega-6 fatty acids to Omega-3. Several studies have established clear association between low levels of Omega-3 fatty acids and depression.

         As in the human diet, cattle feeding or the composition of the ration has significant effect on the fatty acid profile of the final product. The livestock grazing increases to the level of Omega-3. In meat by about 60% and also generates a more favorable ratio between Omega-6 and Omega-3. The meat contains conventional 4:1 ratio of Omega 6:3 in proportion, while the cattle to pasture contains a 2:1 ratio. The amount of fat per serving is highly variable and depends on diet, genetics and the cutting beef. But when the lipid content is standard, a serving of meat from cattle confined with 10% fat, providing 84mg of Omega-3 in 100 according to French et al, 2000. (29). the same lot of livestock to pasture provides 136mg n-3/portion.

         In general, livestock grazing is the shot with weights lower than the confined, producing more total carcass lean meat (less fat). Therefore, the cuts of carcasses of cattle at pasture do not provide the same amount of n-3 lipid percentage with constant. The more lean carcasses have the advantage of a lower percentage total fat and higher proportion of unsaturated fatty acids favorable. However, the carcasses ultra-thin (less than 10 cm of back fat) lead to the cold shortening and reduced tenderness, and, furthermore, the lowest impact on the quality of fat, such as flavor and juiciness.

Conjugated linoleic acid in cattle to pasture

         The term conjugated fatty acid (CLA) is a group of polyunsaturated fatty acids found in beef, mutton, and dairy products, which generally exist as a mixture of isomers of conjugated linoleic acid positional and geometric. These compounds are produced in the rumen of cattle and other ruminant animals during biohydrogenation of linoleic and linolenic acids by anaerobic the ruminal bacterium Butyrivibrio fibrisolvens. Nine different positional and geometric isomers result of this process, in which, cis-9, trans-11 is the most abundant and is in its biologically active form. Cis-9, trans-11 produces up to 75% or more of the total CLA in beef.

         In the last 2 decades, many health benefits have been attributed to CLA in animal experiments, including actions to reduce carcinogenesis, atherosclerosis, diabetes, and establishment of body fat mass.

         The CLA is found naturally in various ruminant meat animals and their dairy products, due to the anaerobic activity of the ruminal bacterium Butyrivibrio fibrisolvens.The green flourishing pastures considered rich in this situation, and thus the species to grazing ruminants have demonstrated 2 to 3 times more CLA that contained ruminant diets with concentrated. On average, the meat of the cattle grazing provides about 123mg of CLA in a standard burger with 10% fat. The same burger made with beef and cattle confined provides 48.3 mg.

         Studies have shown that milk from cows on pasture is 5 times more CLA than milk from confined cattle. The meat of the cattle grazing has 200 to 500% more CLA in proportion to the total fatty acids that the meat of cattle with a diet based mainly on grains.

Source: Licinia De Campos - Nutritionist