Clara Ziezold Position/Title: PhD Student email: cziezold@uoguelph.ca Phone: Office: ANNU 132 Google Scholar Research Gate LinkedIn

In 2021, I graduated from the University of Guelph with a BSc in Animal Biology. The same year, I began my MSc in poultry physiology under the supervision of Dr. Grégoy Bédécarrats and transferred to a PhD program in 2022. 

My interest in poultry research was sparked through working in the turkey breeder industry, which allowed me to gain insight into how the industry operates and some of their current challenges. Interestingly, this experience also allowed me to see how different management techniques and environmental cues, such as lighting systems, can alter egg production efficiency. Thus, during my BSc program, I was particularly intrigued by Dr. Bédécarrats’ work on the impact of light colour spectrum on egg production in laying hens [1, 2]. So much so, that for my undergraduate research project, we conducted a preliminary trial to investigate whether similar results could be achieved in turkey hens with our industry partner, Hybrid Turkeys.

Like chickens, turkeys are seasonal breeders, and changes in daylength serve as the primary cue for reproduction. This phenomenon is termed ‘photostimulation.’ In seasonally breeding mammals, daylength is perceived by the eye. However, in birds, this signal is perceived by light-sensing neurons, or ‘photoreceptors,’ in the deep brain. Therefore, to activate these neurons, light must first pass through the skull and brain tissues. Since red light has the highest tissue penetration power of the visible spectrum, we hypothesize red light improves egg production by stimulating a larger population of deep-brain photoreceptors. However, during our preliminary trial, we also learned that regardless of colour spectrum, turkeys require unusually high light intensities for photostimulation compared to other poultry.

My current research aims to assess how lighting parameters, both in intensity and colour spectrum, affect photostimulation and laying performance in turkey breeder hens. These factors will be assessed through hormonal profiles, gene expression, and egg production. Based on these results, we will have the basis to recommend a lighting treatment that maximizes production sustainability.

Aside from the impact of light on reproduction, there are also metabolic drivers for maturation in poultry [3]. My colleagues Mohammad Bahry and Sierra Schaus focus on this aspect of reproduction in pullets and laying hens.