Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School

Dairy Science

First Advisor

David J. Schingoethe


The value of heat treatment of protein supplements to reduce protein solubility and increase protein utilization was studied in two lactation trials. Experiment I was designed to study the utilization of heat-treated soybean meal (HSBM) by cows in early lactation. An extrusion process with moist heat was used to produce HSBM - a product with lower protein solubility than regular soybean meal (SBM). Ten cows, 3 wks post-partum, were assigned to treatments of HSBM or SBM. Due to a problem in feed bag labeling the concentrate mix containing SBM and corn was not as formulated. A large amount of ground whole soybeans was substituted for SBM making the concentrate mix lower in protein and higher in fat than intended. Milk production was higher for the cows fed HSBM due to either the higher amount of protein that they received and/or the lower protein solubility of that diet. No change was seen in milk fat percent, protein, protein components or total solids. Experiment II used a switchback design with 12 cows to determine the feeding value of a heat treated soybean product. Treatments were commercially available heat-treated soybeans (HTP), the unheated ingredients of HTP (HTP-U) and regular soybean meal (SBM). Nitrogen solubility of the protein sources in 10% Burrough's buffer solution was 9.4, 25.4, and 13.8%, respectively. Concentrate mixes of protein sources and corn were formulated to contain 16% crude protein and fed at the rate of 1 kg/3 kg milk. Production of 4% fat-corrected-milk was similar for all treatments, although, production tended to be highest for cows fed heat-treated soybeans. No differences were observed in milk fat percent or total solids. Protein percent of milk was lower when fed HTP and HTP-U probably due to the higher fat content of those diets. Amounts of long chain unsaturated fatty ·acids in milk fat were increased with HTP and HTP-U diets. Rumen ammonia and serum urea were lower when fed HTP and HTP-U. This study indicates that heating soybeans improved their value slightly as a feed for lactating cows, but milk production by cows past peak production was not significantly greater than production achieved with conventional corn-soybean meal diets.

Library of Congress Subject Headings

Dairy cattle -- Feeding and feeds.
Soybean meal as feed.


Includes bibliographical references (pages 49-59)



Number of Pages



South Dakota State University


In Copyright - Non-Commercial Use Permitted

Included in

Dairy Science Commons