Date of Graduation

12-2025

Document Type

Thesis

Degree Name

Master of Science in Cell & Molecular Biology (MS)

Degree Level

Graduate

Department

Cell & Molecular Biology

Advisor/Mentor

Alrubaye, Adnan

Committee Member

Shi, Ainong

Second Committee Member

Jesudhasan, Palmy

Keywords

air purification; bacterial chondronecrosis; broiler lameness; environmental management; osteomyelitis; poultry welfare

Abstract

Bacterial chondronecrosis with osteomyelitis (BCO) is the primary cause of lameness in commercial broiler production and has a profound impact on animal welfare and cost-effectiveness. The purpose of this experiment was to examine the effect of an air purification system on mitigating BCO lameness in broiler chickens. One thousand eight hundred broiler chicks were reared in two side-by-side research barns. Eight air filtration units were installed in one building, and none in the other. Treatment groups in both houses included positive control birds on wire flooring to induce BCO, as well as negative control, feed additive, vaccination, and a combination of feed additive and BCO vaccine groups on litter flooring. In this experiment, wire-flooring pens were utilized as an infection source, spreading BCO etiological agents to birds grown on litter flooring in the same barn, where treatments of interest are investigated - such as the air filtration system - under the aerosol transmission model of BCO induction. Broiler clinical lameness was assessed daily through necropsy and lesion evaluation to determine the incidence and severity of BCO lesions during the experimental period. Total lame birds in the air-filtered and non-air-filtered facilities were 414 and 473, respectively, P = 0.002. The most significant changes were observed from week 7 onward, especially in the negative control groups (52.0% lameness incidence in the air-purified house vs. 65.5% lameness incidence in the non-air-purified house). Femoral head separation and tibial head necrosis were the most common lesions in clinically lame birds. Overall, the air purification system did not affect broiler body weight and performance, indicating that the impact of the intervention was not through a growth-reducing effect,but rather through potential positive impacts on respiratory and environment-related factors contributing to BCO disease state. These findings suggest that a clean air system could be an effective environmental control initiative to reduce lameness in broiler production at the commercial scale, offering an adjunct, drug-free approach to improving poultry health and welfare.

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