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Wei Zheng

Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School

Dairy Science

First Advisor

David J. Schingoethe


Forty-eight multiparous Holstein cows were used to compare the response of dairy cows to a direct-fed mixture of cellulase and xylanase enzymes (1.25 L of enzyme concentrate/tonne of forage dry matter) applied to the forage portion (60% corn silage and 40% alfalfa hay) of a total mixed diet starting either in theclose-up dry period, at calving, or at peak milk production. Cows were blocked by calving date and, within blocks, randomly assigned to one of four treatment diets. Treatments were: 1) an untreated control diet, 2) enzyme addition to the forage from wk 6 to 18 postpartum, 3) enzyme addition to the forage from calving to wk 18 postpartum, and 4) enzyme addition to the forage from wk 4 prepartum to wk 18 postpartum. Total mixed diets were 65% forage and 35% concentrate prepartum, and 50:50 forage: concentrate postpartum. Production of milk, solid-corrected milk, fat-corrected milk, and energy-corrected milk was higher for cows fed enzyme-treated diets than for cows fed control diet. Production was similar for cows in all enzyme-treated groups, although numerically highest for cows that started receiving enzyme-treated forages right after parturition and lowest when started prepartum. Concentrations of fat, protein, and lactose in milk were similar for all treatments, with yields of protein and fat higher for cows fed enzyme-treated forages. Dry matter intakes and body condition scores, both prepartum and postpartum, were similar for all diets. Eating rates, as determined in two 24-h studies, were similar for control and enzyme-treated diets. Digestibility of diets tended to be slightly higher when forages were treated with enzymes. In conclusion, the feeding of enzyme-treated forages increased milk production. While it did not matter, statistically, when the feeding of enzyme-treated forages started, we recommend starting soon after parturition for economic reasons.

Library of Congress Subject Headings

Dairy cattle -- Feeding and feeds
Proteins in animal nutrition


Includes bibliographical references (pages 59-66)



Number of Pages



South Dakota State University


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