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Understanding variation in the susceptibility to ruminal acidosis Open Access


Other title
rumen epithelia
Ussing chamber
rumen acidosis
rumen pH
short chain fatty acids
Type of item
Degree grantor
University of Alberta
Author or creator
Penner, Gregory
Supervisor and department
Oba, Masahito (Agricultural, Food and Nutritional Science)
Examining committee member and department
Baracos, Vickie (Department of Oncology, University of Alberta)
Matthews, James (Animal and Food Sciences, University of Kentucky)
Beauchemin, Karen (Agriculture and Agri-Food Canada, Lethbridge, AB)
Kav, Nat (Agricultural, Food and Nutritional Science, University of Alberta)
Guan, Leluo (Agricultural, Food and Nutritional Science, University of Alberta)
McAllister, Tim (Agriculture and Agri-Food Canada, Lethbridge, AB)
Department of Agricultural, Food, and Nutritional Science

Date accepted
Graduation date
Doctor of Philosophy
Degree level
Ruminal acidosis is a persisting digestive disorder in modern ruminant production; however, the susceptibility of cows to ruminal acidosis differs among cows fed a common diet. The overall objective of this research was to evaluate factors affecting the susceptibility of cows to ruminal acidosis. This research demonstrated that feeding sucrose in replacement for corn grain to Holstein cows in early lactation does not increase the risk for ruminal acidosis and may actually increase ruminal pH. However, regardless of dietary treatment, cows in early lactation were at risk for ruminal acidosis. In Study 2, diets differing in the forage-to-concentrate ratio were fed to Holstein cows to evaluate changes in the in vivo rate of short-chain fatty acid absorption (SCFA) and the expression of genes coding for transporters and enzymes involved in the absorption and metabolism of SCFA in ruminal tissue. Contrary to the hypothesis, the fractional rate of absorption and expression of genes involved in SCFA absorption and metabolism were not affected by the forage-to-concentrate ratio. Considerable variation among individual cows for the severity of ruminal acidosis was detected for cows on the diet containing the low forage-to-concentrate ratio. To determine the cause of this variation, a ruminal pH measurement system was developed to accurately and precisely measure ruminal pH in non-cannulated small ruminants. Sheep were then subjected to a ruminal acidosis challenge model in vivo, and the absorption of acetate and butyrate across the isolated ruminal epithelia was measured in vitro in Ussing chambers. The results of this study demonstrated that differences in the severity of ruminal pH depression among animals could largely iv be accounted for by differences in the absorptive capability of the ruminal epithelium. In summary, although ruminal acidosis is a common digestive disorder in dairy production systems, variation in the susceptibility to ruminal acidosis is common. The cause for much of this variation is due to differences in the absorptive capacity of the ruminal epithelia.
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
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