Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)


Dairy Science


A complete switchback design using ten lactating cows divided into two groups of five was used to evaluate rations containing either (A) 30% dry matter from aspen pellets, 30% OM from corn silage, and 40% DM from a 28% crude protein· concentrate mix, or (B) 60% OM from corn silage and 40% OM from the concentrate mix, to determine if aspen could serve as a partial roughage for lactating dairy cows. All cows were at least 80 days into lactation at the start of the trial. Aspen contained on a DM basis, 1.9% crude protein, 80.3% neutral detergent fiber, 64.5% acid detergent fiber, and 16.88% lignin. There were no significant ration effects on milk production, composition, or flavor; except for slightly higher amounts of 18:0 and 18:1 fatty acids of milk fat from cows fed aspen. Adjusted means for rations A and B were as follows: milk production, kg/day (20.94, 21.35), % milk fat (3.49, 3.50), % milk solids (12.26, 12.22), % milk protein (3.09, 3.08), and milk flavor judged by an experienced panel using the AOSA-OFISA score card with 10 as best score (8.77, 8.77). Cows fed ration A consumed 19.36 kg DM and those fed ration B consumed 19.28 kg DM on a daily basis. Rumen samples were taken via the stomach tube 3-4 hours after feeding the fourth week of each period. Rumen ammonia was similar for both groups. Concentration of total volatile fatty acids for cows fed rations A and B (48.71, 63.17 moles/ml) was lower for the aspen fed cows. The results of this study indicated that aspen can serve as a partial roughage replacement for lactating dairy cows.

Library of Congress Subject Headings

Dairy cattle -- Feeding and feeds


Includes bibliographical references (pages 40-47)



Number of Pages



South Dakota State University


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Dairy Science Commons