Date of Graduation

12-2021

Document Type

Thesis

Degree Name

Master of Science in Poultry Science (MS)

Degree Level

Graduate

Department

Poultry Science

Advisor/Mentor

Billy M. Hargis

Committee Member

Xiaolun Sun

Second Committee Member

Guillermo Tellez-Isaias

Third Committee Member

Ross Wolfenden

Keywords

E. coli, hatchery, model, poultry

Abstract

Formaldehyde fumigation in poultry hatch cabinets has been utilized for sanitation of hatching eggs for over a century. Formaldehyde is utilized to minimize pathogenic microbes on the surface of the egg as well as the microbial bloom during the hatching process. While formaldehyde is effective, its use is regulated in the United States and Europe due to its carcinogenic nature. Formaldehyde has been shown to damage the cuticle of the egg, cause embryonic death, and damage the epithelial lining of the respiratory tract of freshly hatched chicks, predisposing them for respiratory infection. Alternatives for formaldehyde fumigation must be identified and investigated. Testing potential alternatives in commercial settings is not feasible as new technologies must be invented and integrators do not want to risk economical loss. Moreover, reliable challenge models must be developed to simulate the microbial bloom that occurs during hatch. The purpose of these experiments was to evaluate two neonatal challenge models and their effects on early performance parameters for broiler chickens. In Chapter 2, the efficacy of a spray challenge model is investigated. Utilizing this model, on d20 of embryogenesis, selected chicks, called seeders, were sprayed with a virulent Escherichia coli and placed back into the hatch cabinet to horizontally spread the pathogen. On day of hatch, selected contact chicks were utilized for gastrointestinal tract sampling, while the rest were weighed and randomly allocated into pens to evaluate performance parameters. For two 7-day experiments, the efficacy of transmission was evaluated via enteric bacterial recovery, body weight gain (BWG), and mortality. For Exp 1 and Exp 2, significantly (P<0.0001) more Gram-negative bacteria were recovered from the seeder and contact gastrointestinal samples compared to the negative control samples on day-of-hatch (DOH). Additionally, there was a reduction (P<0.05) in 7-day BWG and significantly (P<0.0001) higher mortality in the contact-challenged chicks compared to the negative control chicks in both Exp 1 and Exp 2. These data suggest that this challenge model could be utilized to evaluate different methods of controlling the bacterial bloom that occurs in the hatching environment.

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