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Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School

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


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