Degree Type

Dissertation

Date of Award

1988

Degree Name

Doctor of Philosophy

Department

Animal Science

First Advisor

Jerry W. Young

Abstract

During the 9 wk immediately after parturition, 18 high-producing cows were distributed equally among three treatments: ad-lib fed control, ketosis-induced, and glucose-treated cows. Ketosis was induced at an average of 44 d postpartum and 29 d after initiation of a protocol that included feed restriction to 80% of ad lib intake and supplemental 1,3-butanediol at 8% of dry matter intake. Treated cows were given the ketosis-induction protocol but also received 500 g glucose/d infused continuously into the duodenum from d 25 to 40 postpartum. Liver and blood samples for ketosis-induced cows were taken at eight stages, which were usually about 7 days apart: prepartal, early postpartum, preinduction, three stages of induction, ketotic, and recovery;Ketosis-induced cows decreased milk production by 31% at ketosis, but values for glucose-treated cows remained constant. Plasma free fatty acid concentrations increased 2.6- and 1.9-fold at two weeks before and at ketosis, whereas glucose-treated cow values increased slightly then returned to baseline. Beta-hydroxybutyrate also increased 5.8- and 8.4-fold for the same time periods for ketosis-induced cows, but only a maximum of 1.6-fold for glucose-treated cows. Plasma glucose was decreased by 20% for ketosis and increased by 9% for treated cows. After parturition, liver glycogen percentages decreased across all treatments and reached essentially zero for ketosis-induced cows two weeks before ketosis. However, values for glucose-treated cows returned to prepartal amounts during glucose infusions. Liver triglyceride increased to 8.5 and 9.8% for two weeks before and at ketosis. Values for glucose-treated cows during the same time periods were 1.3 and 1.1%. Gluconeogenic rates were not different until the ketosis stage when ketotic cows decreased four-fold. Detrimental effects of ketosis therefore seem to begin up to two weeks before clinical ketosis is detected;In vivo kinetic techniques were used to estimate irreversible loss of rumen propionate and plasma glucose at 20, 30, 41, 49, and 60 d postpartum in a subset of four cows from the main experiment. Both glucose and propionate irreversible loss were decreased at the ketosis stage for the ketosis-induced.

DOI

https://doi.org/10.31274/rtd-180813-9337

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Jeffrey James Veenhuizen

Language

en

Proquest ID

AAI8825462

File Format

application/pdf

File Size

149 pages

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