Effects of the periparturient period and feed restriction on metabolism, inflammation, and gastrointestinal tract permeability in dairy cows

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Goetz, Brady
Major Professor
Baumgard, Lance H
Gorden, Patrick J
Appuhamy Jayasooriya, Ranga
Carpenter, Abigail J
Mahanna, Bill
Committee Member
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Animal Science
The partitioning of nutrients towards productive processes (i.e., milk synthesis, reproduction, growth, etc.) is essential for economically profitable and sustainable agriculture. Dairy cows encounter a multitude of physiological, psychological, nutritional, and environmental challenges that often result in immune activation and its accompanied inflammatory response. An activated immune system is energetically expensive and is frequently coupled with hypophagia, both of which reprioritize nutrients towards the immune system at the expense of productive processes. There are a several potential epithelia sources of inflammation in dairy cows including the mammary gland, uterus, lungs, and gastrointestinal tract (GIT). Additionally, dairy cows are subject to several stress insults (i.e., feed restriction, heat stress, shipping, etc.) which can compromise GIT barrier function. The sheer size of the ruminant alimentary canal and extensive exposure to microbial toxins in the pre-gastric fermentation compartments and the large intestine makes dairy cows especially vulnerable to inflammation stemming from intestinal hyperpermeability. Despite focused attention on nutrition and management programs aimed at reducing environmental and enteric pathogen load and ultimately immune activation, suboptimal farm animal performance remains a hurdle to profitable farming. Ergo, identifying nutritional strategies with the potential to alleviate the negative consequences of immune activation on production and metabolism are of growing interest. As part of this dissertation, supplementation of cashew nut shell extract and Bacillus subtilis PB6 were evaluated during the transition period. Additionally, a Bacillus-based direct-fed microbial (DFM) was accessed during and following feed restriction in mid-lactation cows and feeding a multispecies DFM was evaluated during feed restriction in growing heifers. Furthermore, the development, validation, and understanding of biomarkers of GIT health and permeability are imperative to understanding the events that influence GIT barrier dysfunction. The use of the noninvasive permeability marker chromium (Cr)-EDTA and inflammatory biomarkers were utilized in conjunction to provide information on GIT barrier effectiveness and assist in predicting intestinal responses during the transition period and feed restriction. In summary, intestinal barrier dysfunction remains an important issue threatening feed efficiency, milk production, welfare, and farm sustainability. The nutritional strategies evaluated in this dissertation provide novel insight into how the dairy industry can implement approaches to improve animal health, increase animal productivity, and improve farm profit.