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MOF&G Cover Winter 2001-2002

  

  You are here:  PublicationsMaine Organic Farmer & GardenerWinter 01-02Pasture   
 The Benefits of Raising Animals on Pasture Minimize

By Diane Schivera

Eating livestock products can benefit our health and the environment, particularly when the animals are raised eating a pasture-based diet. More and more research is establishing this viewpoint. At MOFGA’s Spring Growth Conference last March, Joel Salatin from Polyface Farm in Virginia addressed these benefits as well as the profitability of raising animals on pasture. Profitability is particularly great because animals that eat grass are healthier than those fed grain.

Products from pasture-raised animals are healthier for you to eat than those from grain-fed animals for many reasons. Basically, fresh pasture plants provide animals with more readily available nutrients, so their products contain more vitamin E, beta carotene, conjugated linoleic acid (CLA) and omega-3 fatty acids. Other benefits may come to light with more research. Vitamin E and beta carotene, the precursor to vitamin A, are powerful antioxidants that, among other functions, help our bodies cope with toxins. Conjugated lineoleic acid prevents many types of tumors and breast cancer in post menopausal women. Omega-3 fatty acids are essential in our diet. All of these nutrients promote a healthy heart, and omega-3 fatty acids have been linked to reductions in obesity, cancer, asthma and depression (because it crosses the blood-brain barrier and helps brain cells function).

We also need omega-6 fatty acids in our diet, and the ratio of omega-3 to omega-6 consumed is significant. Grasses have a lower level of omega-6 than -3, while grain has more 6 than 3. So grass fed beef has a ratio of omega-3 to -6 that is closer to our requirements. Products from pasture-fed livestock also are lower in fat than products from grain-fed animals.

For example, pastured broilers have higher levels of omega-3 fatty acids than grain-fed broilers. Eggs from pasture-fed hens have more folic acid, vitamin B12, vitamin E, and carotenes – especially lutein and zeaxathin, which reduce macular (center of the retina) degeneration – than grain-fed. Turkeys benefit even more than broilers from pasture because they naturally tend to forage more. Pastured lamb has less fat and more protein than grain-fed lamb. Sheep’s milk cheese is higher in CLA, and pastured sheep produce more milk than those fed hay and grain. (Interestingly, sheep’s milk has more CLA than milk from other mammals tested.) Sows’ milk has more vitamin E and selenium, as does pork from those piglets.

Beef animals that are fed either grasses of 12% or legumes of 18% crude protein, with more than 60% digestibility, and neutral detergent fiber of 58% grass – 42% legumes, can produce meat with less marbling and backfat but a healthier omega-3 to -6 ratio, and still be tender (Eramus Okine, “Effects of type of finishing diets on in vitro lipogenesis and oranoleptic qualities of beef,” Beef and Dairy – Research Update 1997-1998, Alberta Agriculture, Food & Rural Development).

The nutritional content of cows’ milk increases with pasture feeding, especially from afternoon grazing (more nonstructural carbohydrates are available) and from early fall pasture (G.E. Shewmaker et al., “Diurnal Variation in Alfalfa Quality and Implications for Testing,” Western Alfalfa Improvement Conference Proceedings, June 1999). After moving from grass to grain, omega-3 fatty acids in milk drop markedly within about 3 to 4 months. Also, the more a cow produces while she is fed grain, the more dilute the components from grass feeding become (S.K. Jensen, “Quantitative secretion and maximal secretion capacity of retinol, beta-carotene and alpha-tocopherol into cows’ milk,” Dairy Research, 66, no. 4 (1999): 511-522).

Butter and cheeses are great sources of good fats, with up to 500% more CLA in these products when they come from pastured versus grain-fed cows, according to a Finnish study (Aro, A., S. Mannisto, I. Salminen, M. L. Ovaskainen, V. Kataja and M. Uusitupa, “Inverse Association between Dietary and Serum Conjugated Linoleic Acid and Risk of Breast Cancer in Postmenopausal Women, Nutr. Cancer, 38, no. 2(2000):151-7). The longer cheese is aged, the lower its level of CLA, so a mild cheddar has more CLA than a sharp. But many artisan cheeses and muenster that undergo bacterial surface ripening have more CLA than those that are not surface ripened.

One reason pasture-fed animals – and their products – are healthier is that the animals eat more on pasture because they like it. This is their natural behavior. On the other hand, confined, grain-fed animals are subject unnatural, stressful environments, such as overcrowding and excessive ammonia in chicken houses. Likewise, when feedlot cattle are taken to slaughter, their hides are often caked with dried manure that is difficult to remove and may contaminate the meat with E. coli 0157:H7, the bacteria that can harm people. Grain-fed beef animals have a much higher level of acid-resistant than of non-acid-resistant E. coli 0157:H7 – a greater concern for people, because it survives more easily in the acidic contents of the human stomach , where it can cause disease. This research was done first at Cornell University (Diez, Bonzalez, T.R. Callaway, M.G. Kizoulis, J. Russell, “Grain Feeding and the Dissemination of Acid-Resistant Eschericia coli from Cattle,” Science, 1998, vol. 281, pgs. 1666-1668), then repeated at the USDA Meat and Animal Research Center in Nebraska (Scott, T., T. Klopfenstein et al., 2000 Nebraska Beef Report, pgs. 39-41, published by USDA).

When animals are fed a diet that is heavy in grain, undigested starch accumulates in the colon, ferments and increases the acidity of the colon contents. E. coli bacteria growing in this acidic environment develop a high level of acid resistance, then become more infectious to humans. If the animals are fed hay or pasture, even for just five days prior to processing, the E. coli population is greatly reduced. This research was repeated at the USDA station because feedlot owners were concerned about what the first study said about their meat. In Nebraska researchers tried many diets to reduce the acid level in the cows’ colons; the hay diet worked best.

Dairy cows raised on pasture generally have fewer foot problems than those raised on grain. Heavily grained cows have a propensity toward acidosis (a blood condition in which the bicarbonate concentration is below normal), because they cannot digest the grain easily. Acidotic cows often have liver problems, laminitis, and are generally “off feed.” Heifers raised on high grain diets accumulate fat in their udder tissue, which reduces their capacity to produce milk. An article in the Journal of Dairy Science (75(1):96-104) stated that intensively grazed cows had lower somatic cell counts than confined cows. A preliminary study done in Germany reported in Nutrition Research (Jahresis, G., et al., 1997, 17(9):1479-1484) showed that organically raised cows on pasture had nearly twice as much CLA in their milk as did the milk from a neighboring, conventional herd.

The increased health of pastured animals has an additional advantage: Antibiotics and other drugs are used less in these animals, so fewer antibiotic-resistant bacteria develop. A study reported in Applied Environmental Microbiology (Langlois, B.E., K.A. Dawson et al., 1998, “Effect of age and housing location on antibiotic resistance of fecal coliforms from pigs in a non-antibiotic-exposed herd,” 54(6):1341-1344) showed that pasture-raised pigs had less antibiotic resistant bacteria than confinement-raised pigs.

Good pasture generally supplies the most economical feed for cattle, sheep and horses during the growing season, despite the fact that intake of nutrients is usually reduced when animals feed on grasses and other hay crops in the pasture, compared with their intake from hay (because the farmer can harvest hay or haylage when nutrient concentrations are optimal, while animals that freely graze do not always eat grass at the prime time). The difference in yield is more than offset by the greater expense for labor, seed and machinery in planting, tilling, harvesting and feeding forage crops. Studies conducted by USDA in seven dairy districts showed that pasturage supplied one-third of the total nutrients consumed by the cows during the year, but cost only one-seventh of the total annual feed cost. One of the biggest problems with confinement feeding is that it involves high capital investment in facilities and equipment and large amounts of purchased supplements. Feeding in confinement costs two to six times more than allowing animals to graze their own forage. A study entitled “At the Crossroads: An Economic Comparison of Grass Based and Confinement Dairying in Wisconsin,” done by EPA’s ACE program, listed a net return of $1.19 for a pasture system and $.73 for a confinement one (Greener Pastures on Your Side of the Fence, by Bill Murphy, Arriba Publishing, 1987). Another way to increase the economic return from a pasture is to follow cows with chickens a few days later. This not only increases the protein levels of the grasses in the field, but the chickens eat the fly and parasite larvae, reducing the need for chemical pesticides.

The Institute for Environmental Research and Education showed a gain of one-half ton per acre per year of carbon on land that is converted from tilled cropland to grassland. Native or planted grasses remove CO2 from the air by photosynthesis and store it in the soil as organic matter or rotting plant parts. This process, known as sequestering, is a way to reduce greenhouse gases. Grassland ecosystems evolved with animals and produce a natural flow of nutrients. Grazing promotes the return of native plants – including red clover. Dairy cows that graze on fields with more than 20% red clover have a significant increase in the level of CLA in their milk.

The environmental impact of livestock production is reduced with pasture-raised animals: Less fossil fuel is required to raise and harvest feed or spread manure. With grain-based systems, more animals are kept than otherwise could be supported by the farm without purchased feed and supplements. The resulting excess manure applied to the limited land area of a farm overwhelms the soil ecosystem, and leached nutrients pollute.

Earthworm numbers in the soil of a permanent pasture system are much higher than in one rotated with field crops. This is just another good indicator of the positive environmental impact of pasture-raised livestock

About the author: Diane is MOFGA’s assistant technical director. You can reach her at the MOFGA office at 568-4142 or at dianes@mofga.org. Some of the information in this article came from www.eatwild.com/, the web page for Jo Robinson’s new book, Why Grassfed is Best (Vashon Island Press, 2000).

    

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