General Concepts and Measures of Oxidative Stress, Implication on Oxidative Balance, an Update on Recent Research in Swine, and Thoughts on Future Research

Optimal nutrient utilization by farm animals is essential for supporting growth and development and is vital in maintaining economical animal production. While profiles, digestibilities, and balances of energy and nutrients of feedstuffs are critical in the nutrient utilization matrix, so is the ability of the animal to balance mechanisms generating oxidative stress with antioxidant defenses within the body. Pro-oxidants can be of environmental, dietary, or metabolic origin, where oxidative stress occurs when free radical production overwhelms the antioxidant defense system. While it is well known that free radicals can bind to or damage proteins, lipids, and DNA, most research to date involving oxidative stress in farm animals has focused on relatively few measures of oxidative stress (e.g., thiobarbituric acid reactive substances) or antioxidant status (e.g., Vitamin E or glutathione peroxidase); often only in one select tissue. Furthermore, traditional metabolite analysis in nutrition studies are hypothesis-driven and are generally designed to study a specific measure for a specific target, which may be limiting our ability to identify potentially novel and unexpected metabolic activities, especially in complex metabolic events and pathways associated with metabolism. It is hypothesized, therefore, that in order to accurately determine oxidative balance of the whole animal, multiple measures of lipid, protein, or DNA damage should be measured in combination with multiple measures of antioxidant capacity. In addition, a more comprehensive and non-targeted approach in experimental design and data analysis is likewise suggested in order to obtain a broader view of metabolic events (e.g., metabolomics, neuro networks, or multivariate analysis) in response to environmental, dietary, or metabolic stressors. While a proportion of this presentation will discuss recent research using peroxidized lipids as an inducer of oxidative stress and key measures of oxidative stress measured in multiple tissues, additional information will be provided on other models to generate oxidative stress (e.g., heat stress, disease, chemical injections, mycotoxins) in an effort to delineate if different stressors cause differential oxidative stress responses requiring stress- or tissue-specific measures, or can whole animal oxidative stress be measured using the same oxidative balance measures.