Masters Theses

Date of Award


Degree Type


Degree Name

Master of Science


Food Science and Technology

Major Professor

Irene Hanning

Committee Members

Federico Harte, Neal Stewart


Foodborne illness and outbreaks associated with poultry products are commonly caused by Campylobacter jejuni or Salmonella enterica. These pathogens colonize the bird intestines during rearing, and if processing, handling or cooking is not done properly, contamination and human illness can occur. Probiotics, prebiotics and botanicals are being evaluated as novel feed additives to reduce pathogen colonization and serve as growth promoter additives in poultry production. Some botanicals are of industrial interest because they are natural antimicrobials or possess beneficial effects on human health. In this research, the application of a botanical (yerba mate) and a probiotic were evaluated as feed additives for broiler chickens to reduce Salmonella colonization. First, the antimicrobial activity of yerba mate extract was evaluated in vitro against Salmonella Enteritidis (SE) and lactic acid bacteria (LAB). Then, in vivo evaluations were conducted. Day-of-hatch chicks were treated with of the following 1) no treatment (control); 2) ground yerba mate in feed; 3) probiotic treatment (Lactobacillus acidophilus and Pediococcus; 9:1 administered once on day-of-hatch by gavage) or 4) both yerba mate and probiotic treatments. At day 3, all chicks were challenged with SE and at day 10, all birds were euthanized and cecal contents enumerated for Salmonella. For the in vitro evaluation, antimicrobial activity was observed against Salmonella, while the same treatment enhanced growth of LAB. For in vivo evaluations, the probiotic treatment significantly reduced Salmonella colonization in the horizontal transmission experiment while none of the yerba mate treatments significantly reduced SE colonization. Yerba mate decreased chicken body weight and decreased the performance of the probiotic treatment when used in combination. It is important to evaluate the use of novel probiotics, prebiotics or botanicals for poultry production. Bird health, growth promoter effects or antinutritional factors of botanicals should be considered before designing diets.

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