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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


Research by others indicated that the addition of urea to diets containing extruded soybeans increased bacterial N and lysine flow· from dual flow continuous culture fermenters. This dietary regime may create a methionine deficiency which could be prevented with ruminally protected methionine. This theory was tested using 28 high producing Holstein cow (14 primiparous and 14 multiparous) fed a concentrate mix containing extruded soybeans and urea with or without 15 g of added DL-methionine supplied as 50 g of ruminally protected methionine product. Treatment periods started wk 4 postpartum and continued through wk 16 with milk production and composition during wk 3 postpartum used as covariates. Cows were fed a 16.0% crude protein total mixed diet of (dry matter basis) 40% corn silage, 10% alfalfa hay, and 50% concentrate mix. Yields of milk (33.8 and 35.0 kg/d) and fat corrected milk (26. 8 and 28. 4 kg/d) were similar (P>. 05), although numerically highest when fed protected methionine. Percentages of fat (2.71 and 2.79), protein (3.02 and 2.98), and solids-not-fat (8.64 and 8.54) were similar (P>.05). Dry matter intakes (20.8 and 19.2 kg/d) were similar between groups (P>.05). Arterial concentrations of methionine were increased by supplemental methionine. Transfer efficiency of amino acids indicated that methionine was changed from first to second limiting by methionine supplementation.

Library of Congress Subject Headings

Dairy cattle -- Feeding and feeds
Milk yield


Includes bibliographical references (pages 39-51)



Number of Pages



South Dakota State University


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