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Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School

Dairy Science

First Advisor

G.A. Harrison


Three experiments were conducted to examine the effects of oilseeds on ruminal microbial metabolism. Experiment 1 utilized six rumen-simulating fermenters in six-7 d periods to screen diets for successive experiments 2 and 3. Fermenters were fed 10 g of their perspective diet twice daily and contained a dilution rate of .05 S h-1 with samples taken 2 h postfeeding on d 4-7. Lnoculum donor was fed for ad libitum intake with a diet consisting of 50% alfalfa hay and 50% concentrate (com/soybean meal). Treatments for Experiment 1 were control (CT), raw soybeans (SB), steam-flaked soybeans (SFS), and whole cottonseeds (WCS). Runs 1-3 tested physical form (oilseeds ground through 1 mm screen versus masticated seeds collected via esophageal cannula) within oilseed type (CT=2.5% EE; SB, SFS, WCS=4.4% EE). Physical form of oilseeds had little effect on microbial numbers or fermentation. Runs 4-6 compared CT diet against two levels of masticated oilseeds (low=3.7o/o EE; high=S.0o/o EE). Microbial numbers were not greatly affected by oilseeds. Compared to control, cultures fed SB diets had higher pH and decreased total VFA concentrations, while fermenters fed SFS diets had lower pH and higher total VFA concentrations. Fermenters fed WCS diets had higher pH and increased acetate: propionate ratios compared to fermenters fed CT diet. Inclusion of oilseeds in diets of 50% alfalfa hay and 59% concentrate altered fermentation in rumen-simulating fermenters but had negligible effects on microbial numbers. Experiment 2 utilized four ruminally cannulated Holstein cows, averaging 41 DIM, in a 4x4 Latin Square. Treatments were the same as Experiment 1 with diets consisting of 25% alfalfa hay, 25% corn silage, and 50% grain (soybean meal and com in CT diet was replaced by oilseed in SB, SFS, and WCS diets) and formulated to contain 17% CP, and 2.8, 5.5, 5.5, and 5.6% EE for CT, SB, SFS and WCS, respectively. Ruminal fluid samples were taken 4 h postfeeding on last 3 days of each 3 wk period. Oilseed diets increased proportions of ruminal butyrate (P

Library of Congress Subject Headings

Dairy cattle -- Feeding and feed
Oils and fats in animal nutrition
Rumen fermentation
Microbial populations
Microbial metabolism


Includes bibliographical references (pages 122-136)



Number of Pages



South Dakota State University


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