Off-campus South Dakota State University users: To download campus access theses, please use the following link to log into our proxy server with your South Dakota State University ID and password.

Non-South Dakota State University users: Please talk to your librarian about requesting this thesis through interlibrary loan.

Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)


Dairy Science

First Advisor

Arnold R. Hippen


There are many forms of soybeans available and fed within the livestock industry including: raw soybeans, extruded soybeans, roasted soybeans, steam-flaked soybeans and several soybean meal varieties. While most of these soybean products have been extensively researched and evaluated as feedstuffs, there is almost no research regarding steam-flaked soybeans. This series of research evaluated the feeding properties of steam-flaked soybeans in lactating dairy cattle. One component of the investigation was an in situ study that evaluated the rumen degradability and intestinal digestibility of steam-flaked soybeans. A second component of this research investigated the effect of particle size on rumen degradabi1ity parameters of steam-flaked soybeans. Finally, the third constituent of this research was a feeding trial where steam-flaked soybeans were included in the diet of lactating dairy cattle at 0%, 5%, 10% and 15% of dietary dry matter. This research demonstrated that steam-flaked soybeans, when ground to 2-mm, have similar rumen degradability to solvent extracted soybean meal and greater overall digestibility than raw soybeans. We also observed that using whole steam-flaked soybeans, as opposed to ground steam-flaked soybeans, increases the rumen undegradable portion of protein and dry matter. Furthermore, it was demonstrated that steam-flaked soybeans, fed to lactating dairy cattle at 15% of dietary dry matter, can replace a mixture of soybean meal and commercial fat sources while maintaining production of milk (42 kg/d), milk fat (3.6%), and milk protein (3.0%). Increasing the amount of steam-flaked soybeans in the diet increased the amount of saturated and polyunsaturated fatty acids in milk fat indicating that steam-flaked soybeans may lead to more complete biohydrogenation as well as being a source of rumen protected fat.

Library of Congress Subject Headings

Dairy cattle -- Feeding and feeds
Soybean as feed


Includes bibliographical references (pages 82-89)



Number of Pages



South Dakota State University


In Copyright - Non-Commercial Use Permitted