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Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School

Dairy Science

First Advisor

D. J. Schingoethe


Twelve multiparous Holstein cows at 48 ± 8 DIM were used in a 4 x 4 Latin square with 21 d periods to determine the effect of replacing soybean meal (SBM) with fish meal (FM) on feed intake, milk yield and composition, blood amino acids (AA), and ruminal volatile fatty acids (VF A). Fish meal substituted soybean meal in an isonitrogenous basis at 0, 25, 50, and 100% of protein supplement. Total mixed diets were (DM basis) 25% com silage, 25% alfalfa hay, and 50% concentrate mix. Intake of DM (27.9, 27.8, 26.1, and 25.8 kg/d for diets 1 to 4, respectively) was similar (P > 0.14) for all diets. Milk yield (37.5, 37.8, 37.2, and 37.7 kg/d) was not affected (P = 0.85) by diets. Milk protein percentages (3.23, 3.24, 3.31, and 3.35) increased (P < 0.02) with 100% FM supplementation, and tended ( P = 0.08) to be higher with 50% FM supplementation compare to 100% SBM diet. Milk fat percentages (3.18, 2.99, 3.04, and 2.87) and yield (1.21, 1.13, 1.11, and 1.06 kg/d) were lower (P < 0.05) with the 100% FM than with the 100% SBM diet. Fish meal supplementation slightly improved Met status. Both extraction efficiencies and transfer efficiencies of AA from the blood by the mammary gland indicated that Met, Lys and Phe were the most limiting AA in all diets. Concentration of omega-3-fatty acids in milk fat (0.54, 0.56, 0.63, and 0.72 g/100 g fatty acids) increased (P < 0.02) as the proportion of FM in the diet increased. Concentration of c9,t11 conjugated linoleic acid (0.39, 0.44, 0.46, and 0.72 g/100 g fatty acids) and transvaccenic acid (1.09, 1.19, 1.28, and 1.54 g/100 g fatty acids) were higher (P < 0.04) with the 100% FM diet than with 100% SBM diet. Molar proportions of acetate ( 63 .1, 60.1, 61.3, and 59.3 mol/100 mol) decreased (P < 0.05) with the 100% FM diet. A total replacement of SBM with FM in the diet of lactating cows would be one way to increase milk protein percentages and the beneficial FA (CLA, TVA, and omega-3 FA) in milk fat .if the cost of FM is comparative with SBM.

Library of Congress Subject Headings

Dairy cattle -- Feeding and feeds
Fish meal as feed
Soybean meal as feed


Includes bibliographical references (pages 53-67)



Number of Pages



South Dakota State University


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