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Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)


Dairy Science

First Advisor

David Casper


dairy cow, feed efficiency, milk production, Saccharomyces cerevisiae fermentation products


This study was conducted to evaluate Saccharomyces cerevisiae fermentation products (Diamond V Original XPC and 2 prototypes) on production efficiency of mid lactation dairy cows. Eighty mid-lactation (164.5 DIM ± 67.5) Holstein cows (56 multiparous and 24 primiparous) were blocked by parity, days in milk, and milk production, and randomly assigned to one of 4 treatments. Treatments consisted of (1) Control (CON): corn silage and haylage based ration; (2) XPC: CON ration with Original XPC added at 14 g/hd/d; (3) Prototype 1 (P1): CON ration with Prototype 1 added at 5 g/hd/d; and (4) Prototype 2 (P2): CON ration with Prototype 2 added at 19 g/hd/d. Treatments were mixed with dried distillers grains and then mixed into a TMR at 454 g/hd/d. The study lasted for 70 d. The first 14 d of the study (d −14 to 0) was used to train cows to use the Calan gate feeding system and cows were fed the C ration during this period. Treatment effects were continuously monitored for the 8 wk experimental period. Dry matter intakes (DMI) were similar (P ≥ 0.10) when cows were fed all treatments (25.7, 26.1, 25.1, and 26.2 kg/d for C, XPC, P1, and P2, respectively). Milk production (33.3, 34.4, 35.5, and 36.8 kg/d) was improved (P < 0.05) for cows fed P2 compared with cows fed CON, with cows fed other supplements being intermediate and similar. Feed efficiency (Milk/DMI) was improved (P < 0.08) for cows fed P1 and P2, compared with x cows fed CON and XPC (1.30, 1.34, 1.49 and 1.41kg/kg). Milk fat content was reduced (P < 0.05) for cows fed P2 (4.17, 3.93, 4.08, and 3.85%) compared with cows fed CON, with cows fed other treatments being intermediate. Milk protein and lactose percentages were similar (P ≥ 0.10) among treatments. Cows fed P2 had lower (P < 0.05) molar percentages of ruminal acetate (63.8, 64, 63.1, and 62.3%) and greater (P < 0.05) propionate (18.9, 19.3, 19.7, and 20.6%) than cows fed other treatments. Supplementing a dairy ration with Saccharomyces cerevisiae fermentation products can improve milk production and feed efficiency of mid-lactation cows.

Library of Congress Subject Headings

Dairy cattle -- Feeding and feeds Saccharomyces cerevisiae Lactation Fermentation


Includes bibliographical references (page 41-61)



Number of Pages



South Dakota State University


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