Degree Type

Dissertation

Date of Award

2017

Degree Name

Doctor of Philosophy

Department

Animal Science

Major

Nutritional Sciences

First Advisor

Lance H. Baumgard

Abstract

Nutrient and energy partitioning toward productive processes (i.e., growth, reproduction, and milk production) is key to economically profitable agriculture. During infection, nutrients and energy are drawn away from profitable purposes to support the immune system. Immunological costs contribute to the economic consequences of sickness that include decreased growth, inefficient feed utilization, poor reproduction, and increased health care costs. Animals experience frequent immune challenges, as bacterial insults can originate from many different scenarios. Understandably, the intestinal epithelium is a focal point of bacterial translocation due to its “gate-keeping” role of simultaneously facilitating nutrient absorption while preventing bacterial infiltration into portal and systemic circulation. Immune insults originating from intestinal bacteria have become of interest as heat stress, feed restriction, and peripheral inflammation contribute to intestinal permeability to luminal content. Additionally, metabolic maladaptation to lactation following calving (i.e., ketosis) in dairy cattle is associated with inflammation, and intestinal-derived endotoxin may contribute to this metabolic disorder. Sickness or suboptimal health, regardless of origin, is an animal welfare issue and an economic burden to animal agriculture. The activated immune system employs a unique metabolism to strategically utilize substrates and ensure its quick and effective response. An activated immune system requires a large amount of energy, and systemic glucose homeostasis is markedly disrupted during endotoxemia. Specifically, activated macrophages and other immune cells become obligate glucose utilizers and hypoglycemia and hyperlactemia are characteristic hallmarks. The increased glucose requirement by the immune system occurs simultaneously with hypophagia and thus reduced intestinally derived carbohydrate precursors. Consequently, there is a negative glucose balance that likely limits the immune response and certainly prevents optimal productivity. Having a better understanding of the nutrient requirements of an activated immune system will provide foundational information for developing strategies aimed at minimizing productivity losses during infection. Furthermore, understanding the etiology of immune system activation in various animal agricultural situations can aid in developing strategies to maximize protection against immune system over-activation.

DOI

https://doi.org/10.31274/etd-180810-4972

Copyright Owner

Sara Kay Stoakes Kvidera

Language

en

File Format

application/pdf

File Size

258 pages

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