Date of Award

5-2026

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Animal and Veterinary Sciences

Committee Chair/Advisor

Ahmed Ali

Committee Member

Jeryl Jones

Committee Member

Mireille Arguelles-Ramos

Committee Member

William Bridges

Abstract

Musculoskeletal health is an important issue in laying hens; however, limited information has been published on the effects of aviary style, management, and supplementary interventions on this problem. This dissertation evaluated the effects of aviary configuration, management strategies, and nutritional interventions on musculoskeletal development, behavioral allocation, production performance, and welfare outcomes in laying hens housed in two commercial non-cage (aviary) systems. Diagnostic imaging, biomechanical testing, muscle dissection, serum biomarker, and behavioral observation measures for each of these outcomes were statistically compared among intervention groups. Aviary configuration significantly influenced patterns of resource use, where an open-system design promoted greater utilization of elevated and enriched substrates. These included perches, nests, and litter areas, ultimately resulting in increased locomotor activity and behavioral engagement. These patterns were associated with statistically significant differences in measurements, including enhanced muscle development, increased bone mineral density, and improved biomechanical properties, but also resulted in a higher prevalence of keel bone damage. In contrast, systems with reduced vertical accessibility showed a statistically greater reliance on wire flooring, which contributed to increased footpad lesions, plumage damage, and non-nest oviposition. Management strategies further modified these responses, as interventions such as litter restriction, structured floor walking, and robotic stimulation altered movement patterns and resource accessibility. These interventions influenced skeletal loading and subsequent musculoskeletal adaptation. These findings indicate that the timing and duration of environmental exposure are critical determinants of long-term skeletal outcomes. Additionally, genistein supplementation employed additional effects on physiological parameters associated with skeletal health. Supplementation was associated with statistically significant improvements in growth performance, bone mineral density, biomechanical strength, and bone formation biomarkers, of which supports its role as a complementary strategy to improve skeletal integrity prior to egg production. Furthermore, risk assessment modeling demonstrated that behavioral allocation was strongly associated with welfare outcomes, where increased use of elevated resources was linked to statistically greater risk of keel bone damage, while increased reliance on wire flooring was associated with higher incidence of integumentary damage. Concurrently, competition for nest access during peak oviposition contributed to increased non-nest egg deposition, particularly in systems with greater navigational constraints. Despite these differences, overall egg production remained consistent across treatments. Collectively, these findings demonstrate that aviary design, management, and nutritional strategies interact to regulate behavior and physiological adaptation.  These findings also suggest that optimizing commercial systems requires balancing behavioral opportunities with skeletal and integumentary health to improve both welfare and production sustainability. Overall, this work fills critical gaps in understanding the trade-offs between behavior, musculoskeletal health, and welfare in non-cage systems, while providing a basis for refining housing, management, and nutritional strategies to improve outcomes.

Author ORCID Identifier

https://orcid.org/0009-0002-2010-6657

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Available for download on Monday, May 31, 2027

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