Theses and Dissertations

Issuing Body

Mississippi State University


Byrd, Allen

Committee Member

Magee, Danny

Committee Member

Bailey, R. Hartford

Committee Member

Wills, Robert W.

Committee Member

Wu, Tung-Lung

Date of Degree


Document Type

Dissertation - Open Access


Veterinary Medicine

Degree Name

Doctor of Philosophy


College of Veterinary Medicine


Department of Pathobiology and Population Medicine


The objective of this dissertation was to (1) determine which grow-out and processing sampling points best predicts and causes Campylobacter later in production (2) identify risk factors within the hatchery that influenced Campylobacter prevalence later in production (3) identify biosecurity risk factors that were associated with Campylobacter presence during production and processing (4) identify farm and production characteristics that were associated with Campylobacter presence later in production, and (5) to estimate the proportion of variance and the intraclass correlation coefficients within the hierarchical levels (complex, farm, bird) of the data. The best predictors of post-chill Campylobacter carcass status were the exterior whole carcass sample in the grow-out environment and the crop upon arrival at the processing plant. The best post-chill causal model contained the grow-out whole carcass. Variables associated with the increased odds of a Campylobacter positive sample included controlling the humidity in the hatchery chick room, 2-4 people handling the chicks at the hatchery, washing the setter twice yearly, 2 or more breeder farms providing eggs for the sampled flock, using low water pressure when washing the hatch trays, having more walk-in doors on the boiler house, the farmer removing the litter from the farm, concrete at most used door of the broiler house, the number of workers that work with the birds during grow-out, having more houses on the farm, standing water on the farm day 1, wood interior walls, a vegetation surface next the house footing, and 6 or less flocks on the litter. Protective factors included the use of footbaths and dedicated shoes, greater frequency of entering the house during brooding, disinfectant added to the drinker lines, having concrete outside the most used door, the cleanliness of the workroom, and harvesting birds at 56-63 days of age. The highest percent of variance occurred at the farm level meaning intervention efforts should focus on factors at the broiler farm level i.e. factors that are different among farms within a broiler complex.



Campylobacter; Broiler; Poultry; Food Safety; Epid