Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School

Dairy Science

First Advisor

David J. Schingoethe


Forty-eight Holstein cows were randomly assigned wk 3 postpartum to a corn or barley diet from wk 4 through 44 postpartum. Cows within diets at wk 14 were randomly assigned to receive 0 (control), 10.3, 20.6, and 30.9 mg/hd/d of recombinant bovine somatotropin injected wk 15 through 44 postpartum. Forage dry matter was 80% corn silage and 20% alfalfa hay. Forage to concentrate ratio in total mixed diets varied from 50:50 to 70:30 with milk production. For the entire lactation, milk production of (29.7 and 29.1 kg/d) and 4% FCM (27.3 and ·25.9 kg/d) was lower for cows fed barley based diets. Percentages of milk fat (3.44 and 3.25) were numerically lower for cows fed barley, while protein (3.36 and 3.36) was similar. Milk production (26.6, 31.0, 31.2, and 28.8 kg/d) and 4% FCM (23.9, 27.1, 27.5, and 28.0 kg/d) was higher for cows injected with somatotropin, while DM intakes (21.4, 22.4, 21.4, and 22.3 kg/d) were similar. Percentages of milk fat (3.39, 3.12, 3.21, and 3.66) and protein (3.43~ 3.29, 3.28, and 3.43) varied. Lactose, SCC, and body weights were similar for somatotropin and dietary treatments. Recombinant bovine somatotropin injected daily during the last 2/3 of lactation increased milk production 8 to 17% and DM intake 0 to 5% for the entire lactation and the increase was consistant across diets.

Library of Congress Subject Headings

Dairy cattle -- Feeding and feeds
Milk yield


Includes bibliographical references (pages 60-70)



Number of Pages



South Dakota State University


In Copyright - Non-Commercial Use Permitted

Included in

Dairy Science Commons