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Research Project: PROCESSING METHODS TO MODIFY THE LEVELS OF BIOLOGICALLY ACTIVE COMPOUNDS IN MILK AND CHEESE

Location: Dairy and Functional Foods Research

Title: Case study: Comparison of milk composition from adjacent organic and conventional farms

Author
item Tunick, Michael
item Van Hekken, Diane
item Paul, Moushumi
item Karreman, Hubert - Rodale Institute
item Ingham, Elaine - Rodale Institute

Submitted to: International Journal of Dairy Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/6/2015
Publication Date: 2/1/2016
Publication URL: http://handle.nal.usda.gov/10113/62622
Citation: Tunick, M.H., Van Hekken, D.L., Paul, M., Karreman, H.J., Ingham, E. 2016. Case study: Comparison of milk composition from adjacent organic and conventional farms. International Journal of Dairy Technology. 69(1):137-142. doi: 10.1111/1471-0307.12284.

Interpretive Summary: Consumers wonder whether or not organic milk is different from conventional milk, but most studies test two herds that are not in the same area, which can introduce soil type and weather conditions as factors. Our laboratory eliminated those variables by comparing milk from adjacent farms, one an organic herd and the other a herd using conventional management. The composition, types of fatty acids, and minerals were measured over 80 weeks, including two warm weather grazing seasons. The only major differences observed were in the fatty acids. Two fatty acids that have been shown to have numerous health benefits, CLA and ALA, were found to be at significantly higher concentrations during the grazing seasons. The organic herd did not consume special feed intended to raise CLA and ALA levels, meaning that farmers can rely on pasture plants to elevate the amounts of these fatty acids in milk. CLA and ALA are likely to be at higher concentrations in organic milk, which is often a factor in consumer purchases.

Technical Abstract: A study of two adjacent dairy farms, one using conventional confined herd management and the other organic management with averages of 53 percent dry matter from pasture during the grazing season, revealed significant differences in the fatty acid composition of the milk. Compared with conventional milk, organic milk had higher levels of conjugated linoleic acid (CLA) and alpha-linolenic acid (the major omega-3 fatty acid in milk), and less stearic and linoleic acid (the major omega-6 fatty acid in milk) during the spring-summer grazing season (S-S). During fall and winter (F-W), the organic milk had higher levels of palmitic and alpha-linolenic acid, and less stearic, oleic, and linoleic acid, than conventional milk. The F-W organic milk provided more total CLA and a-linolenic acid since it contained 4.0 percent fat while the conventional milk and the S-S organic milk contained 3.6-3.7 percent fat. During S-S and F-W, few differences between the two types of milk were observed in protein, solids-not-fat, ash, Ca, Fe, K, Mg, Mn, Na, P, and Zn contents. When removing geography and weather as variables, organic milk appears to yield more CLA and omega-3 fatty acids.