Grass and human nutrition

Authors: KARSTEN, HEATHER - PENN STATE UNIVERSITY; Baer, David

Submitted to: Grasslands
Publication Type: Book / Chapter
Publication Acceptance Date: 3/9/2008
Publication Date: 1/1/2009
Citation: Karsten, H.D., Baer, D.J. 2009. Grass and human nutrition. In: Wedin, W., Fales, S.L., editors. Grassland Quietness and Strength for a New American Agriculture. Madison, WI: American Society of Agronomy. p. 189-204.Grasslands.

Interpretive Summary: Food products from animals that graze grasslands and consume diets high in forages may be better for human health than livestock fed diets with forages and concentrates. Meat from livestock that graze pastures in the United States frequently has less fat and higher concentrations of omega-3 fatty acids and vitamin E than animals fed diets primarily based on grains. Similarly in various studies, dairy cattle that graze pastures and consume diets high in forages produce milk that has higher concentrations of the omega-3 fatty acids than when cows were fed concentrated and conserved forages. Chickens that forage on pasture produce eggs with almost 3 fold more omega-3 fatty aacids significantly more fat-soluble vitamins than poultry fed typical grain-based diets. These differences appear to be due to the nutritional qualities of the livestock diets.

Technical Abstract: Food products from animals that graze grasslands and consume diets high in forages are often better for human health than livestock fed diets with forages and concentrates. Meat from livestock that graze pastures in the United States frequently has less fat and higher concentrations of omega-3 fatty acids (FA), conjugated linoleic acid (CLA), and vitamin E than animals fed diets primarily based on grains. Similarly in various studies, dairy cattle that grazed pastures and consumed diets high in forages produced milk that had 1.3 to 3.8 higher concentrations of the omega-3 FA alpha-linolenic acid, and 2 to 3 times higher CLA concentrations than when cows were fed concentrated and conserved forages. Further, chickens that foraged on pasture produced eggs with almost 3 fold more omega-3 FA and significantly more fat-soluble vitamins than poultry fed typical grain-based diets. These differences appear to be due to the nutritional qualities of the livestock diets. Grassland plant tissues are primarily photosynthetic tissues with chloroplasts that contain a high proportion the unsaturated fatty acids linoleic and alpha linolenic acid. Further, plants that are grazed, rather than dried for hay or ensiled, have higher concentrations of carotenoids and vitamin E than most conserved forages and grain crops that are fed to livestock.