Date of Graduation


Document Type


Degree Name

Doctor of Philosophy in Cell & Molecular Biology (PhD)

Degree Level



Biological Sciences


Douglas D. Rhoads

Committee Member

David S. Mcnabb

Second Committee Member

David M. Ivey

Third Committee Member

Young M. Kwon

Fourth Committee Member

Charles J. Rosenkrans


Broilers, Chondronecrosis with Osteomyelitis, Probiotics, Synbiotics


Since 1945, the market for broiler production has evolved from a collection of smallholder poultry farms into an industry worth billions of dollars. Poultry production has not gone without challenges. Lameness in young broilers is presently a serious issue in the poultry industry for reasons of animal health and welfare, as well as significant lost production and revenue. Bacterial chondronecrosis with osteomyelitis (BCO) is a major form of lameness in broilers. This dissertation contains information about (i) the influence of Staphylococcus agnetis, Staphylococcus saprophyticus, Staphylococcus epidermidis and Enterococcus faecalis on inducing BCO lameness, (ii) evaluation of of probiotics for reducing lameness in a BCO challenge model through promoting gut integrity, and (iii) evaluation of commercial symbiotic for decreasing the number of broiler chickens that develop of BCO lameness. The discovery of dietary supplements that have the potential to promote gut integrity could be crucial to the prevention of BCO. We demonstrated that certain probiotics could reduce the risk of lameness. We investigated one human isolate of Staphylococcus aureus as well as four types of bacteria that were recovered from lame birds: S. agnetis, S. saprophyticus, S. epidermidis, and Enterococcus faecalis. All these bacteria were tested for their ability to induce lameness on wire flooring. Birds that are reared on litter floors are susceptible to developing lameness when even a small amount of bacterial pathogen is introduced into their drinking water. It's possible that the litter-flooring model can more accurately represent broiler operations. Commercial symbiotic have been put through a series of tests to determine whether or not they can decrease the number of broiler chickens that develop BCO lameness. The chickens in this trial were divided into five treatment groups: a control group; three groups receiving symbiotic; and one group raised on wire flooring to stimulate BCO lameness. Probiotics and other feed supplements were demonstrated to reduce lameness in broiler chickens by 20–25 percent in these trials.

Available for download on Monday, October 14, 2024