Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)


Dairy Science


Many factors present in livestock feeds affect the numbers and types of protozoa and bacteria in the rumen. A small particle size of feed and a fast rate of passage of the feed through the ruminant decreases protozoal numbers. Full feeding of a concentrate ration and an acid pH in the rumen also tend to reduce protozoa numbers. Bacteria numbers tend to increase as the protozoa numbers decrease. Knowledge of rumen microflora population changes on different rations is lacking. It is known that restricted-roughage rations will generally cause lower protozoal numbers. Since whey is an available source of lactose and energy, the bacteria and protozoa numbers could population is a good indication of efficient feed utilization. Good growth of the rumen microbial population when adding whey to the ration will indicate its efficient feed utilization. Adding whey products to restricted-roughage rations of cows caused milk fat production to return towards normal (5, 26, 27); however, it was not known which component in whey was responsible for correcting milk fat depression. This study was undertaken to determine the population changes of the rumen microflora when cows were fed whey or whey products on a high concentrate low-roughage ration. The objectives of the study were as follows: l. To determine the total numbers of protozoa per milliliter of rumen fluid. 2. To classify the protozoa into the five main genera. 3. To determine total numbers of bacteria by the direct microscopic count and roll tube methods. 4. To determine the types of bacteria as either starch fermenters, lactose fermenters, or proteolytic bacteria.

Library of Congress Subject Headings

Cattle -- Feeding and feeds
Rumen -- Microbiology


Includes bibliographical references (pages 43-46)



Number of Pages



South Dakota State University


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Dairy Science Commons