Characterizing the effect of commercial growth practices on chicken physiology

In commercial settings, fertilized eggs are separated from the hens immediately after being laid, resulting in no contact between adults and chicks. Contact between adults and progeny is important for vertical transmission of commensal gut bacteria. Indeed, it has been shown that as a result of these growth practices gut microbiota composition and function are impaired. In this work, we characterized the effect of exposing newly hatched chicks to adult gut content on gut microbiota composition and function, specifically on gene expression in the chick`s cecum and bursa samples, to understand the effect of colonization on gut and immune system functions respectively.

We confirmed that exposure to adult gut content resulted in large changes in microbiota composition in all phylogenetic levels. We further show colonization results in modification of gene expression in cecum and bursa tissues. Pathway analysis shows the most significant pathway modified upon exposure is neutrophil de-granulation, implying neutrophil influx in response to commensal colonization. Notable genes affected by colonization include pIgR, encoding the poly-Ig receptor, and muc13, encoding an epithelial mucin. Overall, we detected changes in the metabolic and immune response of newly hatched chicks upon exposure to adult bacterial community, indicating lack of exposure to adults in commercial settings affected normal development. The next phase of study is to understand how these changes in development affect the ability of chicks to respond to infection and commercial immunization protocols which might lead to changes in growth practices and the development of probiotics based on adult bacterial strains.