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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 Casper


The lactation experiment was designed to evaluate a high inclusion rate of forage into a dairy cow ration. Twenty mid- to late-lactation lactating Holstein dairy cows were blocked by parity, milk production, and days in milk (DIM) and randomly assigned to a low (LF) or high (HF) forage diet. Forages were 60% 2012 2nd cutting alfalfa haylage and 40% 2012 corn silage blended on a DM basis and then fed at either 60% LF or 80% HF of the ration DM. Covariatly adjusted milk production and 4% fat corrected milk (FCM)(28.1 and 24.1 kg/d for LF and HF, respectively) were significantly reduced (P≤0.01) by feeding the HF diet compared to cows fed the LF, while milk fat (3.98 and 4.0%), milk protein (3.11 and 3.17%), milk lactose (4.81 and 4.77%), and milk solidsnot- fat (8.87 and 8.77%) percentages were similar (P>0.10) for cows fed both rations. The results support the theory that forage quality, although high, was insufficient to support milk production. The calf experiment evaluated a calf starter (CS) supplemented with live yeast on health and growth of Holstein heifer calves. In July 2013, sixty newborn heifers from a local dairy were blocked into non-supplemented (NS) and yeast supplemented (YS) treatments by weight and total serum protein (TSP) and fed the CS for 80 d. An TSP of 6.5 g/dL (5.5 g/dL is excellent) in both treatment suggested a high transfer of passive immunity. Intake of CS tended (P≤0.09) to be higher for calves fed YS compared to calves fed NS CS (1.01kg/d vs. 1.14kg/d for NS and YS, respectively). Weight gains (69.6 kg vs. 70.3 kg), whither heights (86.9cm vs. 86.4), hip heights (91.4cm vs. 91.9cm), hip widths (27.4cm vs. 27.5cm) and days scoured (5.10 vs. 5.07) were similar between NS and YS, respectively (P ≥ 0.10) leading to the conclusion that the good health and low pathogen load encountered in this study did not warrant supplementation with yeast.

Library of Congress Subject Headings

Dairy cattle -- Feeding and feeds
Dairy cattle -- Productivity
Yeast as feed
Forage plants


Includes bibliographic references (pages 59-66)



Number of Pages



South Dakota State University


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