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Professor

Ph.D. - University of Kentucky, 1979

Phone: 301-405-1366
Email: erdman@umd.edu

Research Interests:

Due primarily to the negative persception of dietary fat, there has been a remarkable change in consumer preferences for fluid milk in the U.S. where --low fat milk (less than 2% fat)- increased from 22 to 62% of total fluid milk consumption in the U.S. over the last 20 years. These changes in consumption patterns may problems for the dairy industry since the average fat content of raw fluid milk has not changed significantly from 3.67% in the last 30 years.

One potential opportunity for regulation of milk fat production is to manipulate the cow's diet. Several dietary factors including diets high in polyunsaturated fatty acids (PUFA) from both marine and plant sources, diets with reduced forage particle size, and high grain diets, are all known to induce depression of milk fat by as much as 40%. We were the first to identify an increase in trans 18:1 fatty acids (tFA) in milk as a factor common in each of these dietary situations. Subsequent experiments with postruminal infusion of fats differing only in cis vs trans fatty acid isomer content showed a direct effect of trans fatty acids on milk fat secretion. There is now evidence that other fatty acids containing trans double bonds such as conjugated linoleic acid (CLA's) may also be involved in diet induced milk fat depression. Trans fatty acids and CLA's are produced as intermediates in the rumen biohydrogenation process where unsaturated fatty acids are hydrogenated to their complementary saturated forms. Two key factors affecting trans fatty acids and CLA production, and milk fat depression in the dairy cow are rumen pH and intake of dietary polyunsturated fatty acids. Although we are confident that absorbed trans fatty acids are the factor which induces milk fat depression in dairy cows, the exact mode of action is unknown. Our recent work suggests that activity of enzymes associated with de novo fatty acid synthesis in the mammary gland are inhibited during diet induced milk fat depression. Our long term goal is to understand the process of diet induced milk fat depression and to develop practical techniques to regulate milk fat production in the dairy cow.

Awards and Honors:
- Northeast American Dairy Science Association-American Society of Animal Science Young Scientist Award, 1990.
- U.S. Patent. Method for regulating milk fat and milk production using trans fatty acid. Joint with M. Keeney, J. Sampugna and B. Teter in Chemistry. Issued May 16,1995.
- American Feed Industries Dairy Nutrition Research Award, 1996.
- Excellence in Research Award, University of Maryland Agricultural Alumni Award, 1998.