Enteric proteomic endocrine pathway changes to day of hatch chicks after in ovo bacterial inoculation

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The Ohio State University

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Microbial populations within the gastrointestinal tract (GIT) have the potential to alter the physiological performance of a variety of systems within poultry. From a production standpoint, the ability to manipulate this population can provide an invaluable way to influence overall health and performance. The objective of this study was to compare the effects of in ovo inoculation with a commercially available LAB-probiotic (L) or two different Gram-negative strains for their influence on the endocrinological profile of day of hatch chicks. At d18 of embryogenesis, eggs were inoculated with sterile saline (S), 102 CFU of one of two species of Citrobacter (C1 or C2), or L. Eggs were hatched by treatment and, on day of hatch, the GIT, duodenum to rectum, was collected from 10 chicks. The extracted protein was subjected to separation by fusion mass spectrometry and identified via Sequest with a Gallus gallus reference in Uniprot. Data was then entered into Ingenuity Pathway Analysis (IPA) and analyzed for differences. All experimental treatments were compared to S in IPA to determine effects on canonical pathway activation and inhibition at p<0.05, with a minimum z-score of +/-1.5. The C1 group showed inhibition of pathways related to insulin and cholesterol regulation and production including HNF1A (z-score -1.969) and HNF4A (z-score -2.000). This is in contrast to C2 which expressed opposite results of these pathways, with activation of insulin and cholesterol regulation (ex: HNF1A z-score +1.982), plus activation of pathways and receptors for sex hormones (Progesterone receptor z-score +1.982) and the precursor to the hormones related to angiogenesis, angiotensinogen (z-score +1.898), among other endocrine-related proteins. The L group showed activation of sex and steroid hormone pathways including corticosterone (z-score +1.949) and steroid hormone receptor ERR1 (z-score +1.948) as well as Insulin-1 (z-score +1.49), and inhibition of calcitriol (z-score -1.709). These changes suggest that neonatal colonization of poultry can affect significant physiological pathways, especially those related to sex and steroid hormones, insulin, and other glucose-regulating pathways, and emphasize the role of pioneer colonizing bacteria in growth and development of perinatal poultry.



Poultry, microbiome, bacterial inoculation, Gastrointestinal Tract, endocrinology, proteomics