Interpretive Summary: Natural light may have little influence on broiler welfare
Artificial lighting has been a standard practice in commercial poultry production for many years, but recently, the provision of natural light to broilers during rearing has gained traction, based on consumer demand for improved bird welfare.
Prior research has studied the effects of lighting management – including photoperiod, light intensity, light source, and wavelength – on bird behavior, health, welfare, and production. However, research focusing on the impact of natural light provided by windows remains limited.
A group of researchers at Auburn University conducted a study to assess the impact of two lighting sources – natural light (NL) and artificial light (AL) – on the fear response and welfare indicators, including footpad dermatitis, hock burn, gait score, and latency to lie. They described their findings in a recent edition of Poultry Science.
For the study, 704 chicks were raised until 56 days of age. The study was set up as a randomized complete block design with two treatments (NL and AL) and eight replications. The NL treatment consisted of natural light supplied through one 1 ft2 window per room supplemented by a single 5,000 K (overdrive 6 W) LED bulb. The AL treatment consisted of a single 5,000 K LED bulb. Treatments were blocked by room location with four AL and four NL replicates on the north and south side of the facility.
Over the course of the study, several observation tests were conducted to measure fear response (novel object test, response to observer test, and novel environment test) and several welfare parameters were measured, including footpad dermatitis and hock burn, gait score, and latency to lie test.
Among the study findings, the researchers reported that:
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Broilers raised under AL were more reluctant to approach within a 1-m radius of the novel object than NL broilers (P = 0.03)
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Birds exposed to NL had a shorter mean latency to approach the novel object (69.9 seconds) compared to those under AL conditions (181.4 seconds; P < 0.01)
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No treatment effects were found in the response to observer test, novel environment test, or welfare parameters except for footpad dermatitis (birds under NL showed lower scores than AL birds (P = 0.03).
The researchers noted that the light provided during rearing can alter the bird’s ability to perceive their environment and, thus, affect the bird’s affective state and fear response. For birds reared in NL conditions, the broader range of light wavelengths and higher light intensity may have made the object more appealing, potentially encouraging greater interaction with the novel object. This would suggest that the difference between the two treatments in the novel object test may be due to changes in the object’s appearance under natural lighting rather than a true reduction in fearfullness.
Overall, the study suggests that the provision of NL did not show significant improvement in fear levels or the welfare measures of leg health on broiler chickens.
What does this mean for producers?
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Adding natural light provided by windows did not yield a significant improvement in fear levels or welfare measures, particularly leg health.
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There are several predisposing factors that can influence broiler leg health that may outweigh potential benefits provided by natural light.
The full paper, “Evaluating the impact of natural and artificial light treatments on fear response and welfare parameters in commercial broilers,” can be found in Poultry Science and online here.
DOI: 10.1016/j.psj.2025.106343
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