Dry Period Nutrition and Hepatic Metabolism of Fatty Acids and Glucose in Transition Dairy Cows
Litherland, Noah B.
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https://hdl.handle.net/2142/83597
Description
Title
Dry Period Nutrition and Hepatic Metabolism of Fatty Acids and Glucose in Transition Dairy Cows
Author(s)
Litherland, Noah B.
Issue Date
2006
Doctoral Committee Chair(s)
James K. Drackly
Department of Study
Animal Sciences
Discipline
Animal Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Animal Pathology
Language
eng
Abstract
In experiment 1, liver slices from multiparous Holstein cows on day -30, -14, 1, 14, and 28 relative to calving were used to determine the effects of far-off and close-up diets on palmitate metabolism in vitro. During the far-off period, d -60 to -25, cows received a low energy control diet fed ad libitum (100NRC) to meet National Research Council (2001) nutrient requirements, a moderate-energy diet fed ad libitum to exceed NRC recommendations for NE L by >50% (150NRC), or the same diet fed at restricted intake to provide 80% NEL of requirements (80 NRC). During the close-up period (day -24 until parturition), cows were fed ad libitum to meet NRC recommendations or in restricted amounts to provide 80% of calculated NEL requirements. The close-up dietary treatments had little effect on palmitate metabolism. Excessive energy intake during the far-off and close-up period promoted decreased hepatic palmitate oxidation and increased esterification of palmitate. In experiment 2, additional liver slices from experiment 1 were used to determine conversion of propionate or alanine into glucose or oxidation. Cows fed restricted amounts of energy in the far-off period had greater hepatic capacity to perform gluconeogenesis both prepartum and postpartum compared with those fed excess amounts of energy relative to requirements. Data from the first two studies indicate that far-off dietary treatment can alter hepatic metabolism. In experiment 3, an in vitro screening system was developed to test the effects of peroxisome proliferator activated receptor-alpha (PPAR-alpha) agonists on oxidation of palmitate by liver slices. The response by liver slices to both natural and synthetic PPAR-alpha agonists was intriguing and led to applications in vivo. In experiment 4, male Holstein calves were treated with both synthetic (clofibrate) and naturally occurring (fish oil) PPAR-alpha agonists to determine if male Holstein calves are a suitable model for studying liver fatty acid metabolism in adult Holstein cows and to determine if PPAR-alpha agonists alter ruminant liver fatty acid metabolism. Increases in hepatic lipid metabolism were much less than those reported in rodents treated with clofibrate or fish oil indicating that ruminants may be weak responders to PPAR-alpha agonists.
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