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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 in a 2 X 2 factorial arrangement to study interactions of bovine somatotropin (bST) and nutrition during weeks 5 through 20 postpartum. Main effects were bST (-or+ 10.3 mg per day) and diet (control, C; or high protein and energy, HPE). Diet C was formulated to contain 16.3% crude protein and 1.65 Meal net energy for lactation (NEL) per kg dry matter (DM) for lactation, while the HPE diet was formulated to contain 18% crude protein and 1.74 Meal NEL/kg DM, with additional energy as fat from extruded soybeans and calcium salts of fatty acids. Diets were 50:25:25 concentrate: alfalfa hay: corn silage (DM basis). Bovine somatotropin increased yields of milk (37.9 versus 40.9 kg/day) and of 4% fat-corrected milk (32.3 versus 35.7 kg/day). The HPE diet increased milk yield (38.5 versus 40.3 kg/day) with yield of 1% fat-corrected milk higher for HPE+ (36.0) than HPE- (33.6). Percent fat was not affected by treatment (2.99, 3.17, 3.07, and 3.17 for c-, c+, HPE-, and HPE+, respectively). Percent milk protein was reduced with added fat and only partially increased with HPE+ (3.07, 3.00, 2.81, 2.86). Dry matter intake was not significantly elevated by bST (22.8 versus 23.5 kg/day), but was lower for HPE {23.8 versus 22.4 kg/day). Increased dietary protein and energy augmented the milk production response to bST.

Library of Congress Subject Headings

Bovine somatotropin
Dairy cattle -- Feeding and feeds
Milk -- Composition
Milk yield


Includes bibliographical references (pages 66-80)



Number of Pages



South Dakota State University


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