Date Available

4-18-2023

Year of Publication

2023

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Agriculture, Food and Environment

Department/School/Program

Animal and Food Sciences

First Advisor

Dr. David L. Harmon

Abstract

To continue to meet the demands of increasing food production and environmental sustainability, new strategies are needed to enhance the efficiency of finishing cattle production. A review of the literature identified several nutritional and physiological constraints that limit the ability for cattle to digest starch and absorb glucose from the small intestine. Comparative sequencing analyses revealed a missing region of the sucrase-isomaltase protein which could affect the capacity for starch digestion in cattle. Post-flaking sampling and handling recommendations were generated based on a series of experiments to improve estimates of starch availability and flaking consistency for commercial feedlots and laboratories. Increasing flake density and increasing starch retrogradation could potentially be implemented as processing strategies to shift the site of starch digestion to the small intestine and reduce substrate available for ruminal methanogenesis. For smaller cattle feeders where flaking corn is not an option, low to moderate inclusion of fine-ground corn in finishing rations might be a suitable processing alternative. Feeding anti-coccidial compounds with saponins did not decrease methane production; yet, future attempts to replace antibiotics in finishing cattle diets should attempt to replace the anti-coccidial and anti-methanogenic activity of ionophores. A novel, in vivo animal model was developed to selectively target increased endogenous pancreatic and/or small intestinal carbohydrase activities to evaluate physiological mechanisms to increase small intestinal starch digestion. Next-generation RNA sequencing revealed that exogenous glucagon-like peptide 2 administration affected several metabolic pathways and molecular functions of the jejunal mucosa, which could potentially improve growth, health, and feed efficiency of feedlot cattle. These findings could be used to further develop strategies to optimize starch digestion, improve flake quality, and reduce methane emissions of finishing beef cattle.

Digital Object Identifier (DOI)

https://doi.org/10.13023.etd.2023.055

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