Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School

Dairy Science

First Advisor

David J. Schingoethe


Large amounts of dried whole whey (86% of concentrate mix, 60% of total dry matter intake) were fed to four Holstein steers in place of corn and soybean meal in the control diet to evaluate the extent and site of lactose digestion in the ruminant's digestive tract. Diets consisted of 70% of the dry matter as concentrate mix and 30% as corn silage fed ad libitum as a total mixed ration. Weight gains and dry matter intakes were similar for steers fed dried whole whey or control diets. Samples of rumen contents from steers fed dried whole whey contained more butyrate, less propionate, and less ammonia than from animals fed control diets. No lactose was detected in the rumen or small intestine indicating that it was completely digested. Lactase activity per gram of intestinal tissue was significantly greater in two of fifteen t issue segments and numerically greater in the proximal third of small intestine of steers fed the control diet. Lactase activity per gram tissue protein was similar for both treatment groups throughout the small intestine. Lactase activity was greatest in the proximal third of the small intestine with little activity in the distal third of the small intestine irregardless of diet. Lactase activity of intestinal contents was similar for both treatments, being highest in the duodenum and lowest in the ileum and large intestine. Since no lactase apparently escaped the rumen, differences in intestinal lactase may not be expected. Lactase activity may have been affected by the amount of total carbohydrates entering the small intestine rather than just the amount of lactose entering. Digestibilities of whey diets were higher for ash and numerically higher for energy and organic matter, while digestibilities of acid detergent fiber and cellulose was numerically lower. Cattle have the capability to consume large amounts of dried whey without digestive disorders or reduced rates of gain.

Library of Congress Subject Headings

Beef cattle -- Feeding and feeds


Includes bibliographical references (pages 35-40)



Number of Pages



South Dakota State University


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Dairy Science Commons