Date of Graduation


Document Type


Degree Name

Doctor of Philosophy in Poultry Science (PhD)

Degree Level



Poultry Science


Billy M. Hargis

Committee Member

Guillermo Tellez

Second Committee Member

Lisa R. Bielke

Third Committee Member

Luc R. Berghman

Fourth Committee Member

Raphael L. Andreatti Filho


Food Safety, Organic Acids, Poultry, Probiotics


Improving production parameters and controlling foodborne pathogens have been challenges to the poultry industry. Salmonella has been the most common bacterial pathogen in laboratory confirmed foodborne illness cases, and contaminated poultry and poultry products have been identified as the most important source of transmission of Salmonella to humans. Therefore, research on effective interventions to reduce Salmonella transmission at the poultry production level has gained attention. Initially, a series of studies was conducted to evaluate the use of selected organic acids in controlling foodborne pathogens and improving poultry performance. Then, the characterization and application of lactic acid bacteria and Bacillus spp. based probiotics in poultry, and their combination, along with early nutrition, with glutamine supplementation were evaluated. In the first study, the use of organic acids in vitro and in vivo with broiler chicks (crop and cecal tonsil enumeration) reduced the incidence of Salmonella Typhimurium. In the second study, an organic acid product showed reductions in body weight loss during feed withdrawal and transportation, and meat quality improvement of broilers during commercial conditions. In the third study, organic acid mixtures were used in wash solutions for the reduction of spoilage and foodborne bacteria from chicken skin. The results demonstrated a reduction on pathogenic and spoilage bacteria from chicken skin, suggesting improvement of raw poultry safety properties. The fourth and fifth studies were conducted to identify and characterize probiotic strains of lactic acid bacteria and Bacillus spp., respectively. The evaluations included tolerance and resistance to acidic pH, high osmotic concentration of NaCl and bile salts, in vitro assessment of antimicrobial activity against enteropathogenic bacteria, and susceptibility to antibiotics. The last series of studies was carried out with the objective of evaluating the effects of glutamine supplementation in combination with a lactic acid based probiotic, a Bacillus subtilis probiotic strain, and a commercial nutritional supplement for neonatal broilers and poults, on Salmonella Typhimurium colonization. The results showed increased body weight gain, villus height, villus width, and villus surface area index in chickens treated with neonatal nutrition and/or glutamine, and a reduction in Salmonella incidence and nitric oxide from ileal tissues of treated groups.