Date of Graduation


Document Type


Degree Name

Master of Science in Poultry Science (MS)

Degree Level



Poultry Science


Guillermo Téllez

Committee Member

Billy M. Hargis

Second Committee Member

Annie M. Donoghue


Biological sciences, Aflatoxin b1, Biodegradation, Broilers, Dfm, In vitro digestion, Intestinal inflammation


Poultry health has been traditionally maintained by hygenic measures, vaccinations, and the use of antibiotics. Modern husbandry management considers the use of probiotics as a natural way to protect birds against many everyday pathogens. Different strains of Bacillus spp. have proved to have beneficial effects in poultry production. However, the most used bacterium in commercial probiotics is Lactobacillus, a vegetative cell. In contrast, Bacillus spp are bacterial spores, highly resistant to harsh conditions, which makes them preferable, in some cases, to Lactobacillus because of shelf life and storage conditions. There is published information regarding mycotoxin detoxification by bacteria. Mycotoxins are a common threat for the poultry industry and different management strategies have been implemented to avoid their negative impact in the poultry industry. Additionally, not much information is provided on the effect of mycotoxin on intestinal inflammation. In chapter one, the ability of Bacillus spp. as direct-fed microbials (DFM) to biodegrade aflatoxin B1 (AFB1) by using an in vitro digestive model simulating in vivo conditions was evaluated. The experiment was performed with three groups: a) control feed; b) control feed contaminated with 0.01% AFB1; c) control feed contaminated with 0.01% AFB1 supplemented with 109 spores/g. In vitro digestion time was insufficient to confirm biodegradation of AFB1. In chapter two, two experiments were conducted in broilers to evaluate the effect of 3 concentrations of AFB1 (2, 1.5 or 1 ppm of AFB1) on gastrointestinal leakage and liver bacterial translocation (BT). Results from these experiments suggest that AFB1 does not increase gut leakage. In chapter three, three independent experiments were conducted to evaluate the biodegradation potential of previously selected Bacillus spp. provided as DFM in broiler chickens consuming feed containing different concentrations of AFB1: a) 2 ppm AFB1; b) 1.5 and 1 ppm AFB1; c) 500 ppb and 50 ppb AFB1. Even though the individual isolates incorporated in the DFM showed some in vitro activity to biodegradate AFB1, when administered in the diets at 5 different concentrations of AFB1, no significant performance differences were observed when compared with their respective control diets.