Date of Graduation

8-2025

Document Type

Thesis

Degree Name

Master of Science in Poultry Science (MS)

Degree Level

Graduate

Department

Poultry Science

Advisor/Mentor

Weimer, Shawna

Committee Member

Kegley, Elizabeth

Second Committee Member

Erf, Gisela

Third Committee Member

Karen Christensen, Karen

Fourth Committee Member

Weimer, Shawna

Fifth Committee Member

Williams, Zac

Keywords

activity; broiler; fear; lighting; stress; wavelength

Abstract

Lighting influences broiler production, health, and behavior. Due to their advanced visual system, avian species perceive a wide spectrum of light. The objective of this study was to investigate the effects of white (W, 350 to 780 nm) blue (B, 450 nm), and green (G, 560 nm) light on broiler production, processing performance, activity, fear, stress, blood cell profiles, tibiotarsi (tibia) morphology, and depth perception. Day-of-hatch by-product chicks from a Cobb 500 female line (N=600) were randomly assigned to 12 pens (N=4 treatment replicates). Body weight and feed consumption were recorded on day (D) 0, 14, 28, and 41, and feed conversion ratio was calculated. Depth perception was assessed using the Visual Cliff (VC) test (D1, D7, and D26), and fear was measured using the Tonic Immobility test (D12 and D33). Blood was drawn for leukocyte and plasma corticosterone concentrations (D21 and D41). On D41, thermal images of the head were taken to measure surface temperatures (eye and beak), and the bursa of Fabricius (bursa) was extracted for relative bursa weight. Accelerometers were adhered to birds Week 2 (D11 to D14) and Week 5 (D38 to D41), and left and right tibiotarsus (tibia) were extracted (D41) for morphology. After sampling, the remaining broilers were processed. Minimal differences were found for live production, stress, fear, or tibia morphology. Broilers in W were more likely to cross the depth line on D1 than B and G broilers during the VC test (P< 0.0001), indicating poorer depth perception. Broilers in B had reduced lymphocyte (P=0.01) and T cell concentrations (P=0.009), suggesting poorer immune function. Activity was greatest for G broilers at Week 2 and lowest for W in Week 5 (P=0.0005). Broilers in the B group had the greatest rack and skin yields (P< 0.0001), had the lowest fat pad yields (P=0.02) and greatest leg quarter yields (P=0.01), and W had the greatest breast (P=0.01) and white meat yields (P=0.001). These results suggest that light color can be strategically used to target production and welfare goals, with green light stimulating activity and white light improving processing yields.

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