Date of Graduation


Document Type


Degree Name

Master of Science in Poultry Science (MS)

Degree Level



Poultry Science


Billy M. Hargis

Committee Member

John R. Barta

Second Committee Member

Samuel J. Rochell

Third Committee Member

Guillermo Tellez

Fourth Committee Member

Christine N. Vuong


Blackhead disease, Histomonas meleagridis, Histomoniasis, Turkey


Histomoniasis, commonly known as blackhead disease, has increased in prevalence due to the regulatory ban of prophylactics and therapeutics within the past 30 years. The objective of this thesis was to evaluate the efficacy of selected dietary chemoprophylaxis candidates as well as an in vitro live-attenuated vaccine candidate Histomonas meleagridis for prevention of histomoniasis. Chapter one addresses deoxycholic acid and a biliogenic diet intended to endogenously increase production of this secondary bile acid. Deoxycholic acid was effective in vitro but failed to prevent histomoniasis when evaluated during the in vivo experimental disease trial with turkeys. The biliogenic diet did not reduce disease prevalence. Chapter two addresses dietary inclusion of 0.2% boric acid to prevent disease. The selected concentration of boric acid was unsuccessful in disease prevention. Chapter three addresses the experiments conducted to evaluate select ages, doses, and routes of a candidate live-attenuated vaccine. The live-attenuated vaccine candidate has exhibited slight reduction in histomoniasis severity when administered intracloacally on d14. Although the practicality of this current experimental vaccine administration approach may be limited, further research must be conducted in order to further elucidate conferred immune response and investigate the viability of this vaccine.