Document Type

Thesis - Open Access

Award Date

1983

Degree Name

Master of Science (MS)

Department

Dairy Science

First Advisor

David J. Schingoethe

Abstract

Two rumen fistulated Holstein cows, weighing approximately 550 kg, were used in a switchback design experiment to evaluate the effects of consuming large amounts (38% of total ration dry matter) of dried whey on rumen microbial protein synthesis. Cows were fed total mixed rations consisting of (dry matter basis) 45% corn silage, 10% alfalfa hay, and 45% concentrate mix. The concentrate mix was primarily corn and soybean meal (control) or 85% dried whole whey. Dry matter intakes averaged 16.4 and 15.3 kg/day for control and whey diets. Concentrations of bacteria and protozoa in rumen contents were estimated using diaminopimelic acid and aminoethylphosphonic acid, respectively, as markers. Diaminopimelic acid-N as percent of bacterial-N was similar for both diets (.61 and .63% for control and whey diets). Likewise, aminoethylphosphonic acid-N as percent of protozoal-N was similar for both diets (.17 and .19% for control and whey diets). For the control diet, total rumen-N was estimated to be 45% bacterial-N and 27% protozoal-N. Bacterial-N and protozoal-N, respectively, accounted for 52 and 22% of the total rumen-N in the cows fed the whey diet. Rumen fluid volume (33.8 and 39.2 liters for control and dried whey diets) and dilution rates (10.2 and 12.8%/h), as estimated with polyethylene glycol, were higher when fed dried whey. Rumen ammonia (5.0 and 3.4 mg/dl) was lower when fed dried whey. Butyrate (16.5 and 24.4 moles/100 moles total volatile fatty acids) was higher while propionate was lower (32.4 and 23.2 moles/100 moles total volatile fatty acids) when fed dried whey; concentrations of other volatile fatty acids were similar with both diets. Bacterial synthesis appeared to be increased when cows were fed a diet containing large amounts of dried whey.

Library of Congress Subject Headings

Cattle -- Feeding and feeds
Whey
Rumen -- Microbiology
Microbial proteins
Proteins -- Synthesis

Description

Includes bibliographical references (pages 57-69)

Format

application/pdf

Number of Pages

76

Publisher

South Dakota State University

Included in

Dairy Science Commons

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