Modern broiler chickens exhibit a differential gastrointestinal immune and metabolic response to repeated CpG injection relative to a 1950s heritage broiler breed

Authors: AYLWARD, BRIDGET - University Of Delaware; Johnson, Casey; PERRY, FAMATTA - University Of Delaware; WHELAN, ROSE - Evonik Corporation; Arsenault, Ryan

Submitted to: Frontiers in Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/14/2024
Publication Date: 11/1/2024
Citation: Aylward, B.A., Johnson, C.N., Perry, F., Whelan, R., Arsenault, R.J. 2024. Modern broiler chickens exhibit a differential gastrointestinal immune and metabolic response to repeated CpG injection relative to a 1950s heritage broiler breed. Frontiers in Physiology. 15. Article 1473202. https://doi.org/10.3389/fphys.2024.1473202.
DOI: https://doi.org/10.3389/fphys.2024.1473202

Interpretive Summary: A comparison was done between a modern meat-type chicken and a 1950s meat-type chicken to understand how genetic selection and breeding can affect the ability of the modern meat-type chicken to respond to exposure to part of a bacterial pathogen. CpG is commonly found in potential foodborne bacteria and is known to trigger a specific immune response. By giving the same immune challenge to the two types of chickens over time, we were able to see the differences in immune activation and immune development between them. We found that the 1950s chickens’ immune response was more regulated and adaptive, while the modern chickens’ response was less balanced. We can use this information to understand the changes that breeding and genetic selection have caused in the modern broiler and identify targets for improvement to make the birds more resistant to bacterial colonization.

Technical Abstract: The Athens Canadian Random Bred heritage broiler breed, which has not been selectively bred since the 1950s, is a point of comparison to the modern-day broiler and could highlight potential genetic-derived differences in immune responses. To observe the modern and heritage birds’ immune responses in action, the innate immune ligand CpG oligonucleotides were administered at multiple time points through the birds’ lives from the day after hatch to day 35 post-hatch. Tissue samples were collected and used for kinome array analysis to measure kinase activity in immunometabolic signaling pathways in the gut tissue. The modern birds’ response to the treatment was more innate and showed evidence of insufficient energy. The heritage birds’ response to the treatment was adaptive, with metabolic changes indicative of a well-regulated response. Overall, the results from this study suggest that modern broiler chickens do not adequately balance resources between growth and immune responses, and this deficit is most evident around the two-week post-hatch time point. This is a critical time for these birds, as their muscle deposition continues to accelerate, and they are vulnerable to disease challenges and bacterial colonization. Ideally, future work can clarify the reason for this response discrepancy in the modern broiler and therapeutic interventions to rescue this phenotype could be elucidated.