Date of Graduation

5-2025

Document Type

Thesis

Degree Name

Master of Science in Poultry Science (MS)

Degree Level

Graduate

Department

Poultry Science

Advisor/Mentor

Alrubaye, Adnan A.

Committee Member

Sun, Xiaolun

Second Committee Member

Jesudhasan, Palmy

Keywords

BCO; bone; Broilers; eBeam-inactivated vaccine; lameness; probiotic

Abstract

With the global population already surpassing 8.2 billion and expected to reach 9.7 billion by 2050, the poultry industry has seen a surge in demand due to its unmatched efficiency and affordability for consumers across the globe. Selective breeding and quality nutrition developments since the industry's commercialization have allowed producers to grow broilers up to 7 pounds by market age. While this extraordinarily efficient process has allowed quality poultry products to be available worldwide, the modern-day broiler has developed a multitude of musculoskeletal issues. Due to the lack of integral skeletal development to match the rapid production of muscle tissue, producers are experiencing an assortment of lameness issues. Bacterial chondronecrosis with osteomyelitis (BCO) is currently the most prevalent lameness disease in modern broilers. BCO accounts for the majority of mortality and culls related to lameness in the commercial broiler. This bacterial disease is associated with a combination of poor gut integrity (“leaky gut”), aerosolized bacteria, poor skeletal integrity, and mechanical stress on the long bones of the leg. Opportunistic bacteria such as Staphylococcus spp., Enterococcus spp., and Escherichia coli hematogenously spread from the small intestine to microfractures in the growth plates of weight-bearing bones. Bacterial colonization leads to infection, inflammation, necrosis of bone tissue, and eventual death. In addition to the economic loss associated with lameness, BCO is considered a significant animal welfare issue as birds experience extreme discomfort and are often unable to access food and water properly.

In Chapter One, I reviewed the literature utilized in developing my understanding of BCO. The overview presented was established and improved through my experience in co-writing a review publication on the topic, as presented in Chapter 2. Chapter Two presents a complete literature review of current publications relating to BCO. In addition to the foundational knowledge built by Dr. Wideman and Dr. Alrubaye, findings since Dr. Wideman’s 2016 review have revealed more aspects related to BCO etiology, which are presented here.

In Chapter Three, we tested the efficacy of using a supplemental probiotic program alongside a multivalent electron beam (eBeam) vaccine in reducing the incidence of BCO in broiler chickens. At hatch, birds received an Enterococcus faecium spray (E. faecium 669, at 2 × 109CFU/bird), and, from day 1 to day 56, drinking water was treated with a triple-strain Bacillus-based product (B. subtilis 597, B. subtilis 600, and B. amyloliquefaciens 516 at 1 × 109 CFU/bird/day). Chicks were divided into five treatment groups under an aerosol transmission challenge model to simulate treatment effects in a commercial setting. The treatment groups included a positive control group on a wire-floor pen (T1), a negative control group (T2), a group receiving only the probiotic program (T3), a group receiving only the multivalent vaccine (T4), and a group receiving both programs (probiotic supplementation and multivalent vaccination). Broilers were assessed daily for clinical lameness from day 22 until trial completion at day 56. The data collected presented significantly reduced lameness in T3, T4, and T5 when compared to T1 and T2.

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