Environmental and management stressors to which livestock are exposed account for tremendous losses annually to livestock producers throughout the United States. Developing effective management systems and/or intervention strategies to help animals cope with negative effects of these stressors on health and production requires a thorough understanding of biological responses to these stressors. Research interests are directed at examining circulating levels of specific blood constituents recognized as key players in an animals' biological response to stress. Measures of behavioral responses have been incorporated into studies to more fully understand cause and effect relationships involved in compromised animal well-being.

DNA analysis of antibiotic resistant E. coli.
Antibiotics are used commonly in livestock systems. Antibiotics continue to play a major role in combating disease organisms, while subtherapeutic use increases animal performance, decreases pathogen loads, and lowers prevalence of organisms causing foodborne illness in humans. There are concerns, however, that use of antibiotics in animal agriculture may be partly responsible for emergence of antibiotic-resistant bacteria, which in turn may decrease effectiveness of similar antibiotics used in human or animal medicine. A primary research focus is to characterize effects of antibiotic use and animal management on antibiotic resistance in bacteria. Additionally, genes that lead to antibiotic resistance in animal and human pathogens, location of specific resistance genes, and the prevalence of "integrons" in animal and foodborne pathogens are being characterized. A number of growth promoting antibiotics have been effective dietary additives for livestock. However, with continued emphasis on reducing antibiotic use in livestock operations, alternative additives are being evaluated for their effects on GI health, intestinal pathogens, and foodborne bacteria.

Mastitis is a complex multifactor disease and is likely the most costly disease affecting animal agriculture in the world. Control is extremely difficult due to diverse types and sources of mastitis pathogens coupled with a poor understanding of bacterial and host factors associated with the disease process. Mastitis caused by environmental pathogens such as Streptococcus uberis and Escherichia coli is a serious problem in herds, and can become a significant problem in dairies that have controlled more common mastitis pathogens.

Invasion of milk secreting cells by mastitis pathogens.
Current mastitis research focuses on identification and characterization of mastitis pathogen virulence factors and their relationship with immunity to mastitis, and upon improving mammary gland health by examining regulation of cellular immunity during disease progression. Studies aimed at mastitis pathogenesis, enhancing mammary gland immunity, and development of new vaccines against mastitis pathogens that are refractory to current methods of mastitis control are likely to have huge payoffs in the future as use of antibiotics in the dairy industry come under greater scrutiny by federal regulatory agencies.